Looking for the companion slides? You can find them here.
Heat pumps fail homes for one reason more than any other: someone guessed instead of measured.
This isn't the first time heat pumps have hit the market. An earlier wave crashed and burned, and the trust took decades to rebuild. Eric Fitz wants this round — what he calls electrification 3.0 — to end differently.
Eric is co-founder and co-CEO of Amply Energy, an ACCA-certified Manual J software company. He's a mechanical engineer, sits on a technical committee, and co-hosts The Heat Pump Podcast with me. In this talk, recorded at the Building Performance Association's annual conference in Columbus, he laid out his full sizing playbook.
This post breaks his system into plain steps. You'll learn how to calculate loads, verify duct capacity, and select equipment with Manual S — plus the quick field checks that make each step practical.
Heat pump design asks contractors to balance many forces at once. Comfort, efficiency, heating loads, auxiliary heat, duct limits, operating costs, and the upfront price all compete. Eric calls the complexity fun, since it creates opportunity. But mistakes carry a heavy cost.
The biggest risk sits at the very start. A lot of contractors treat the load calculation as the finish line. Eric argues it's only the starting point. Manual J defines the problem — what the home needs. Manual S then selects the solution — the right equipment.
Each step feeds the next. A sloppy load calculation poisons every decision after it.
"This is the old garbage in, garbage out problem."
Equipment selection is worthless without an accurate load number behind it. And bad outcomes spread fast: an unhappy homeowner tells ten people about a failed install, while a good experience only reaches a couple.
"Load calculation is just one side of the sizing coin."
Equipment selection is the other side.
Part 1: Manual J Defines The Problem
Manual J calculates the heat losses and gains for a home. It covers sensible and latent cooling, linked by the sensible heat ratio. Eric insists on ACCA-certified software, since some tools borrow the name without the certification. And be aggressive with your assumptions, as the book itself instructs. If a window has blinds, assume they sit at least half closed on design day — don't give the home credit for wide-open glass on the hottest afternoon of the year.
Part 2: Duct Capacity Sets The Limit
Duct capacity is its own check, separate from Manual J and Manual S. In a retrofit, you're rarely designing new ducts. You're testing whether the existing ducts can deliver the airflow a heat pump needs — and heat pumps often need more CFM than the furnace they replace. If the ducts fall short, fix the restrictions before you quote any equipment.
Part 3: Manual S Picks The Equipment
Manual S sizes equipment against the Manual J loads. Eric calls it Goldilocks sizing: not too big, not too small. A new version arrived about 18 months ago with heat-pump-specific updates, and its normative section is free on ACCA's website. For variable-capacity units in wet climates, it simplifies down to four capacity ratios.
Good design shows up in small field habits. Eric shared several checks that take minutes and remove the guesswork.
Take low-E glass. The coating changes both cooling and heating loads, yet looks clear to the eye. Hold a flashlight or a lighter up to the window and study the reflections. A double pane shows four reflections; if one has a different tone than the others, the glass has a low-E coating. The whole test takes five to ten seconds.
Infiltration gets the same treatment.
"Do a blower door test. That's the most accurate way to quantify these loads."
A measured CFM50 number replaces the visual tightness guess, which carries real error. In Eric's own home, shifting that one assumption from average to semi-loose adds almost half a ton of heating load.
Duct checks work the same way. Measure total external static pressure with a dual-port manometer. Compare the readings around the filter and the coil to find which side is restricting airflow. Then read the blower table to get the actual CFM.
Most failures trace back to a handful of repeat mistakes.
First, guessed inputs. That half-ton swing from one tightness assumption is the whole problem in miniature. In summer, a similar shift can double the latent load.
Second, choked airflow. Air handlers are rated near half an inch of water column. Push past 0.8 and fan motors start failing early.
"You've got a one-inch MERV 13 filter that's just choking that whole system."
A restrictive filter is the most common culprit. The fix is counterintuitive: a thicker four-inch filter is less densely packed, so it drops static pressure rather than adding to it.
Third, bad fittings. One sharp 90-degree turn with no turning vanes can equal 80 feet of straight duct.
Fourth, oversizing. Oversized units short cycle, which swings temperatures and hammers the compressor. In a humid climate the coil never runs long enough to reach dew point, so moisture stays in the air and mold can grow. The unit also spends most of its time near minimum capacity — often its least efficient zone.
Eric closed with a clear action list. Run it in order.
And don't go looking for the single best unit, because there isn't one.
"This is a trick question. There isn't necessarily a perfect piece of equipment."
In Eric's example, three different units all passed Manual S. Panel capacity, budget, and duct limits decided the real winner — which is exactly why the conversation with the homeowner matters as much as the math.
[00:00:00] - Episode Teaser
[00:04:06] - Heat Pump Design Fundamentals and the ACCA Design Process
[00:07:27] - Understanding Load Drivers: Temperature, Windows, and Infiltration
[00:14:02] - Window Performance, Low-E Glass, and Shading Effects
[00:20:11] - Verifying Insulation and Building Envelope Conditions
[00:26:26] - Duct Leakage, Static Pressure, and Measuring Airflow
[00:44:48] - Heat Pump Performance Data Explained
[00:52:57] - Manual S Sizing Rules and Heat Pump Selection
[01:11:07] - Balancing Comfort, Efficiency, Auxiliary Heat, and Real-World Constraints
[01:17:05] - There Is No Perfect Heat Pump: Making the Best Choice
[01:19:37] - Closing Remarks
00:00:00.000 — 00:00:42.000 · Speaker 1
Over sizing dramatically over sizing, particularly in a humid climate. Let's say a place like Louisiana, you can get some really scary issues with mold growth, right? If that equipment is constantly cycling on and off, or if it's short cycling, the equipment is not running. If the equipment is not running to actually move the air across the coil, we're not going to be extracting any moisture.
And then if we're really short cycling, that coil might not ever get cold enough to actually reach dew point and pull moisture out of the air. Interestingly, on the undersized side, it's actually gonna be a good thing for indoor air quality because that equipment is going to be running almost all the time, and we're going to be moving air across that filter.
Things can be really good from a high tech perspective.
00:00:46.080 — 00:01:53.040 · Speaker 2
Hey everyone. Ed here I want to introduce you to my co-founder and good friend of over 25 years, Eric Fitz. Eric is good at a ton of stuff I'm not good at. Frankly, that's one of the reasons I love running a company with him. This episode is fun for me because you can hear exactly what Eric is passionate about and what he's good at. This is Eric giving a talk at the Building Performance Association's annual conference from a couple months ago. It's all about heat pump system design. He takes you from the depths of manual J. To what to look out for in a duct system, to how to pick equipment in a way that goes way beyond just what's in manual S. You'll hear him field questions from the audience. You can't always make out the question itself, but Eric does a great job repeating each one so you get a feel for like the back and forth with the audience. I just think it's a super educational and illuminating episode. You'll also get a sense for the problem we at ampullae are obsessed with.
As you listen to this, you may find yourself thinking quite a few times like, oh, it shouldn't be this hard to design a heat pump system. And you're right, it shouldn't. That's exactly what we're trying to fix with our software. This one's for folks building heat pump focused businesses who want to get the technical design. Absolutely right. And one plug for you. We have a manual s heat pump sizing spreadsheet available for download on our website. If you love nerding out on Heat pump system design, download it and let us know what you think of it. The link is in the show notes. Okay, on to the episode with my good friend and co-founder, Eric Fitz.
00:01:56.960 — 00:03:05.800 · Speaker 1
All right. I am super excited to present this morning. Like Wade said on designing heat pump systems that won't come back to haunt you. This is a presentation, but I really want to make it a conversation. So I encourage you if, as I'm going along, questions pop up like just raise your hand, yell them out. I want to have a little dialog, a little back and forth while we're going.
I think that keeps it more engaging, more interesting, and but we'll certainly have time at the end for questions as well. All right. Let's jump into it. So just a quick overview. I'll do a quick intro on myself in a moment. We're going to talk about Manuall Jay. This is what the House needs. We're going to get into how to measure duct capacity.
Why understanding duct capacity is really important especially if you're thinking about installing heat pumps. And then we're going to get into some heat pump performance characteristics. These are kind of important fundamentals so that you can get into selecting the right equipment and actually applying many less correctly throughout.
I'm going to talk about a whole bunch of really interesting trade offs. I'm going to use some real world examples. I can get into details like auxiliary heat design, airflow, that kind of stuff. And then I also am going to mention a bunch of best practices and resources throughout.
00:03:06.960 — 00:03:42.160 · Speaker 1
Um, all right. So I'm I'm co-founder and co-CEO of Amply Energy. We are a Acca certified manual J software platform. It works on an iPad. We can help you design and sell heat pumps a better, smarter, faster. I'm also co-host of the Heat Pump podcast with my longtime longtime friend and co-founder, Ed Smith to check that out if you haven't.
I'm a mechanical engineer by training. I've been designing software and hardware for the last 20 years or so, and I just I love building science. I am a total manual j nerd. I sit on a technical committee. I love this stuff, so I'm really excited to get into it today.
00:03:43.920 — 00:11:59.430 · Speaker 1
All right so heat pump design. It's it's complicated for sure because of those complications I actually think it makes it pretty fun. Um, it creates lots of opportunity from those challenges. And it's, it's it's hard because we're trying to balance a lot. We're trying to deliver comfort and hopefully efficiency to our end customer while we're thinking about heating loads, whether or not we might need some auxiliary heat, sensible cooling, latent cooling, concerns about low load cycling, whether or not we have sufficient duct capacity to deliver all this energy to the spaces in the building.
How this all affects operating expenses for the homeowner, and of course, how this all affects the upfront cost. Because we want to sell this design, we want to end up doing the install or run out of business. So it's a lot. Now the good news is ACCA has an entire design series that follows a logical sequence that kind of helps us work through this process.
There are a bunch of different ACCA manuals. We're really going to focus on manual J and manual S today. So like I said, manual J, this is the problem. This is what the home needs. It should not be confused with the solution. Sometimes folks think, oh, the end of the whole process is doing a load calculation.
That is not the case. Load calculation is just one side of the sizing coin. And so the solution. We use manual S to properly select equipment and to figure out what's the right equipment to solve that problem that LJ helps define. And what's really important here is that getting into designing and sizing a piece of equipment into manual s, it's essentially worthless unless you've done a thoughtful manual J first, because the outputs for manual J are an input into manual S.
This is the old garbage in, garbage out problem. All right, so before we can really get into equipment selection we're going to talk a little bit about manual j. So manual J itself we could do an entire week long course just on manual J. It's an incredible standard. It's been evolving for many years. I'm just going to do a quick overview and get into really some tips that I have found that are really useful for conceptually understanding manual J and then verifying important details in the home that make you really successful doing load calculations.
So is what the home needs. It is a entire set of processes math, engineering equations that help us figure out what are the heat losses and what are the heat gains in a home. We typically think about the cooling loads in terms of both sensible and latent. This will come up later, but we relate those cooling components to this sensible heat ratio.
This is simply the sensible cooling load divided by the total cooling load. All right most important point here. Do a manual j load calculation. It needs to be a with a piece of software that is Acca certified. There are unfortunately some other tools calculators out there that like they mentioned the word manual J out there, but they're actually not a certified product.
Use a manual J certified product and be aggressive with your assumptions. This is called out. I think it's in the fourth page of the multi hundred page book to be aggressive and pay attention. Important details. So what we mean by that is if you're looking at a window, you're in a customer's home and you can see it's got blinds.
Don't assume that on design day that those blinds are just going to be wide open. You should take credit for those blinds that they're at least going to be halfway closed on a hot summer day. All right. So let's talk about the main drivers of loads. While we need to pay attention to all the different details, there's hierarchy, at least from my perspective, of like where I pay attention to most.
And so fundamentally, foundation of key transfer is primarily driven by the difference in temperature. And so if we use the design temperature in my home in the wintertime is five degrees, the standard for indoor design is 70 degrees. So I've got a 65 degree difference in temperature 65 degree delta t.
This is what's doing driving all that those conduction heat transfer. And this is driving those big loads related to infiltration and so on and so forth. The point here is don't mess around with these. All right. There's a lot of thought that's gone into the weather stations. The data that's been collected over many decades, particularly from Ashrae.
Don't mess with these temperatures because it'll lead to all kinds of bad stuff, because this is the foundation of the whole calculation process. So from there, typically and again this varies based on climate zone windows and or infiltration are usually the next biggest drivers for loads in a home.
Now there's obviously edge cases, but generally speaking that's pretty common scenario. Walls obviously have a big impact. Ducts and ceilings, floors and doors and internal loads can be significant, but often there are a relatively small detail in a home for typical single family home. Well, why is this so?
This is actually some square foot measurements of key components in my home. It's really common to have this sort of breakdown where I've got relatively low amount of surface area of windows in my home compared to walls, ceilings and floors are kind of somewhere in between. This all kind of makes sense.
But things get really interesting when we overlay the conductive or insulating properties of these different materials alongside their surface area. And so while windows are relatively small amount of surface area in a home, they're typically have the absolute worst performance when it comes to insulating the home from those outdoor temperatures.
And so if we now do the this is the heating load calculations, we can really see the impact. So windows because they are almost six times worse ability to insulate compared to walls. They just have a massive impact in a lot of cases. So I'm skipping over infiltration because it's a whole thing on its own, which I'll talk about in a second.
But walls are right up there because they're very high surface area and they're kind of like, okay, in terms of how much insulation is in that that cavity. Typically, floors are interesting that floors in most homes are over a closed crawlspace, over a basement. And so you actually have a much lower delta t.
Write that the air temperature in that basement or that crawl space is not actually at outdoor design temperature. So we just have lower heat transfer in general, even though it's relatively high surface area. All right. So infiltration I love speaking at this conference because just about everybody knows what infiltration is here.
This is all this unintentional air leakage in the building through all the imperfections in the home. It's driven by the stack effect in the wintertime, where we've got airflow coming through the sill, typically in a basement, rising up through the home and exiting into the attic space that reverses in the summertime, and we drive hot air from that act space into the building and then out through the bottom of the home.
This is a very, very sensitive assumption in manual J, particularly in heating dominated climates. So manual J, the kind of standard method is this tightness approach, where you're using a visual inspection of the home to kind of build a case for how tight is that home. It ranges from loose all the way up to tight.
And then there's the semi tight average and semi loose. In between I'm just showing three of the options. Well what I want to point out here for my home which has a 65 degree delta t, just this one assumption where I go from average to semi loose. That adds almost a half a ton of heating load in my home. So be really thoughtful if you are using this tightness method and even better, you should be doing a blower door test and you should use a CFM 50 value actually, or testing the home that is way more accurate and definitely the preferred method.
If you're experienced and know how to use a blower door test on the cooling side on a comparative basis, it's much lower impact, right? We have this the same scale here between these two charts. And that's because that delta t in most homes, again, if it's a heating dominated climate, it's much lower in the summertime.
But you still need to pay attention here because similarly there's sensitivity. There can be an infiltration as one of the biggest drivers of latent loads in a home. And so we're. It's summertime. It's hot and humid out. We're jumping from the semi tight to semi loose. That doubles the latent load alone.
All right again use two blower door tests. That's the most accurate way to quantify these loads.
00:11:59.790 — 00:12:01.350 · Speaker 3
You mentioned in.
00:12:01.990 — 00:12:07.990 · Speaker 4
The initial guess on whether it's average semi tight or semi loose.
00:12:09.430 — 00:12:13.070 · Speaker 3
Do you think that people can reliably visually make that guess.
00:12:13.590 — 00:13:05.910 · Speaker 1
So I'll repeat the question I mentioned. They're asking about how this visual inspection method for figuring out semi tight average semi loose. It's tough. I definitely this is why I say we should be doing a blower door test that's preferred. I think with a lot of field experience you can build a pretty good case for this, but it's still it is a guessing game, right?
You're looking at the sill in the basement of a home and you're like, can I see daylight or not? Right. You're then looking if it's a single story ranch and you've got a bunch of canned lights, you're looking for signs of dust and streaking on the sheetrock of the ceiling, and you're building a case based on those factors.
The protocol itself has like a two page description for all how all of these kind of layout and the things you should be watching for. But it's tricky. It's a real challenge. Yeah, there definitely could be error in that process. So again, I strongly encourage folks to do a blowtorch test.
00:13:06.430 — 00:13:13.550 · Speaker 5
But is there a number? Oh Lord. Or if you could kind of gauge that what you're saying average is semi rules.
00:13:13.590 — 00:13:38.230 · Speaker 1
Yeah. So from the calculations that are going up behind the scenes in manual J, an average tightness roughly corresponds to an ACH of five. A loose roughly corresponds to ACH ten. Yeah. So it's documented in the book. There's a couple of you can kind of correspond these to ACH numbers. Yeah. ACH yeah. Air changes per hour.
Sorry. Yep. Another question.
00:13:38.310 — 00:13:43.070 · Speaker 3
Vintage has a lot to do with what. What is average. So yes, I don't know how used to that average.
00:13:43.110 — 00:16:30.070 · Speaker 1
Totally. It's tricky. I agree. All right. Speaking of things that are tricky, windows are really tricky. In manual day, there are just a ton of different options. This is something that I really encourage folks to pay attention to, and it can seem a bit overwhelming at first, but there's actually a few details that are just super critical, that are actually easy to verify and have a huge impact.
All right. So first off, this is an obvious intuitive one. The direction of windows facing makes a big difference, right? The Lowe's on a south facing window versus a north facing window. It's almost six times different based on that direction alone. But if we look at I'm using a baseline window there in the upper right calling that like that's the sort of normalized load that has a single pane clear glass, good old fashioned window.
And then if we start layering in other parameters that we can adjust like internal shading. This is also somewhat intuitive. If you've got blinds on a window and they are partially closed, that's going to block sunlight from coming into the home. That reduces the loads. Overhangs are super sensitive, especially in more southern latitudes.
So if you're in like Miami, kind of Key West, Florida, every one foot of roof overhang creates ten feet of shading when it really matters later in the afternoon. It's less sensitive in northern climates just because of the latitude and the angle of the sun, but it still matters. So if we've got just a two foot overhang and then we jump to a three foot overhang, that three foot overhang that reduces the cooling load of that window by almost 75%, because a huge component, particularly for south facing windows, it's that solar gain that's coming through that window.
All right. Next big question is whether you have clear glass or low glass. And this is super confusing because when you look at a window like yes it's clear I can see through the window, like, what is this supposed to mean? This is a really sensitive assumption, and it has a big impact on both cooling loads and heating loads.
So a low window, not only does it have a coating that helps reduce solar gain, They almost always have some kind of inert gas in between the panes that also reduce conductive loads. So this is something that really matters both for heating dominated and cooling dominated climates. And we'll talk in a second about how you can easily verify this.
Insect screens is something that people overlook all the time. Full outdoor insect screen reduces the cooling loads on a window by up to 20%. Okay, it's actually blocking light from coming through that window and matters. So don't overlook insect screens. It's super easy. You just look at the window.
Do I have insect screens or not? Are they full outdoor or are they half outdoor? Super easy to catch this. And if we combine all these different factors. So we've got a low E three foot overhang and insect screens, that's an 80% reduction in cooling loads. And this is on just a single pane old fashioned window.
All right. So all these different things really add up. And most of them you can just easily verify with visual inspection.
00:16:30.110 — 00:16:32.110 · Speaker 3
You enter all that in the manual change.
00:16:32.190 — 00:16:38.070 · Speaker 1
Yes. Yep. Yeah. Question was do you enter all that into the manual J. The short answer is yes. Yep. Great.
00:16:38.550 — 00:16:43.550 · Speaker 5
Have we got the longer days in the North that could get in some.
00:16:44.710 — 00:19:09.230 · Speaker 1
So the tables behind that are used for the calculations in manual J. They are sensitive to latitude. And so they. There's something called the shade line multiplier which takes some of that into account. Yeah. Great question. All right. So how do we figure out if we have this really sensitive assumption.
Clear windows versus low E windows. Great news is you can figure this out using just a powerful light source. This could be the LED flashlight on your phone or tablet. You can use a lighter. You can use a little laser tape measure anything that's got a nice bright light source. You hold it up to the window.
I'm using this example with a flame with a lighter. And you just look at the reflections. So in a double pane window you've got four surfaces. You have the first pane of glass and there's the interior surface and then the surface on the other side, and then you have the exterior pane of glass and you've got two surfaces.
If you notice that just one of those reflections looks like a different tone, a different color than the others. That means you've got lily glass. It's amazing. Like once you've done this a few times, it literally takes five seconds. 10s and you've answered this fundamental question that has a huge impact on load calculations.
And what's really cool is that based on which one of those reflections, you see the color difference, you actually know which surface of the glass that low coating is on. And so that's another question that you need to know in manual J in order to kind of figure out what kind of windows you have. The last thing that's tricky is so these different coatings that are the low E coating that's on the window, it has a different emissivity value.
And that can really only measure that with like a $2,000 piece of equipment. But there's windows typically have different emissivity based on the climate zone. So for example, in southern latitudes where we really want to prevent solar gain, in the summertime we have very low emissivity values. And that tries to reduce as much of this infrared light.
That's really driving a lot of that solar gain as possible. But in northern latitudes we have a more relaxed emissivity value closer to 0.2, because we actually want some solar gain to happen in the wintertime in particular. That's a big benefit for energy purposes in the home. So we have a little help article that covers some of this stuff.
But that's how you figure out whether you have low or clear windows. Yeah. Go ahead.
00:19:09.670 — 00:19:10.990 · Speaker 3
So it gets pretty.
00:19:10.990 — 00:19:21.790 · Speaker 6
Complicated depending on how much overcast you have in the winter. And a lot of northeast climates, for instance, in the Midwest and very low overcast. So the benefit of the heat gaining.
00:19:21.830 — 00:19:26.710 · Speaker 3
Is I factored in that's missing because it overcast is so extensive for some nuts.
00:19:26.750 — 00:22:04.070 · Speaker 1
Yeah. So Emanuel J. For heating purposes, solar gain is completely ignored because of the complications around, you know, what is actually going on, and also because in the wintertime, typically design temperatures are at like three, 4 or 5:00 in the morning when there is no sun at all. So we just from a manual perspective, lots of thoughtful people have considered this problem.
They said we're just not going to include solar gain, you know. All right I love the questions. Keep them coming. All right. So the next thing and I again I feel like folks in this room really got this nailed. But if you're new to this process for me there's a couple of tricks for just how do you verify what kind of insulation you've got in the wall?
A lot of folks, when their first getting into load calculations, if they don't have a background in building science, they're like, I don't know. I don't know how to figure it out. I can't see into the walls. Well, actually, there's some ways to figure it out. I look at the depth of that wall and I look at a window.
I open the front door. I just look at how thick that wall is, because the most basic thing that I'm trying to figure out is, do I have two by six construction or not? If I've got two by six construction, this is really the advent of building codes in the US. You pretty much are going to have 19 in that cavity. There are some exceptions to that, but you're generally going to have some significant insulation in that wall cavity because when building codes arrived, energy codes arrived and we were consistently insulating walls.
Now, the thing that's tricky is if you've checked that wall cavity or the wall thickness or it's obvious the home was built in 1900, you've got two by four walls. You might have nothing in there, or you could have something or something in between. So that's where a little bit more work is required. And the simplest trick if you don't have infrared camera and other tools, other methods that are a little bit more advanced, you can use a $3 drain, unclog a little plastic tool.
You can get these on Amazon. I have no affiliate sales relationship with this company, but basically anything that's nonmetallic, you can take off that outlet cover and you can just poke into the wall next to that junction box and just see if you pull out some fiberglass hairs. See if you pull out some dense pack cellulose.
See if you pull out anything. Right. And then you can at least verify. Do I have something in the walls or nothing at all. Because like that is a huge swing in your load calculations, right? If you have nothing versus something. All right. Attics. This is a great one. You just need to stick your head up there and use your eyeballs.
You're trying to verify if you've got some fiberglass bats or like, Holy cow. Pretty much nothing up there. And you can get more sophisticated and just measure if you've got loose fiberglass or loose cellulose, just measure that depth. Right. And then you can figure out what the insulation is. Go ahead.
00:22:04.310 — 00:22:17.350 · Speaker 4
So in many homes I the older homes I've been into, it's really worth going around the thermal camera because these walls have been worked up, they've been remodeled. And so as a result, they very.
00:22:17.350 — 00:22:21.590 · Speaker 3
Likely have different levels of insulation depending on which wall you're looking at.
00:22:22.550 — 00:22:45.430 · Speaker 1
Yeah. So the comment was that it can really be worth it, especially for really old homes to walk around with that, infrared camera just to see the variation that's going on. There's certainly scenarios I've seen in the field where it's a newer home, and for whatever reason, someone just forgot to put insulation an entire wall.
That's obviously harder to catch for using these, like ad hoc methods versus an infrared camera to identify that issue. Go ahead.
00:22:45.470 — 00:22:46.870 · Speaker 3
I don't know if you're eventually.
00:22:46.870 — 00:23:14.030 · Speaker 7
Going to get to actually the hang up day. I have an easy time with natural gas, oil, propane, but can't do a heat pump, can't get it come out correctly. We don't know why that's what popping that eventually red one. So because I can get the beaches to work out great and it shows me 90% efficiency for a natural gas, 8% efficiency, whatever.
Final install. And you get it almost every time. I can't get the pump right.
00:23:14.230 — 00:24:46.310 · Speaker 1
Okay, my quick response with a question or comment was that you're struggling, trying to figure out load calculations for heat pump versus a furnace versus an oil boiler. We'll get into this a bit more, but just remember that load calculations Manual J really has nothing to do with the equipment. It's about the home.
It's about heat transfer through the envelope. And the only piece where it kind of gets into the equipment is related to the duct system, which we'll touch on a second. But I'm hoping as we get into manual s, maybe that'll reveal some of the confusion around some of the stuff. All right, so while you're up in the attic, you should also be just looking around.
Do I have any venting? If you have venting in an attic, that makes a big difference. That reduces those temperatures, particularly in the summertime where if you've invented attic, it can get up to 160 degrees. So if you have venting, that makes a big difference in floors, in basements, usually we have access to these places.
Again you just need to use your eyeballs. See what's going on in there. Do you have insulation in the floor Joyce. In that ceiling of the basement or not? Is there insulation in the rim, or do you have a situation like this on the right here, where it's a whole lot of nothing going on in this crawlspace? And then duct insulation.
This is super, super sensitive in manual J Again while you're up in that attic, you're in that crawlspace where that duct work may be located. Use your eyes. Hopefully, if it's more modern equipment that's been installed, you can just read the R-value right off of the insulation on this flex duct in this example.
And again you're just trying to verify like do you have something that looks pretty good. You got insulation or something really scary like this on the right.
00:24:46.310 — 00:24:49.590 · Speaker 3
What do you mean when you said duct insulation is super sensitive.
00:24:51.070 — 00:25:11.750 · Speaker 1
Yes. So it's super sensitive meaning a small change in your assumption. So going from like R4 to R6 makes a big difference in terms of load calculations, especially if your duct work is in an attic where you've got really high temperatures in the summertime and really low temperatures in the wintertime.
That's what I mean. Does that make sense?
00:25:11.790 — 00:25:14.950 · Speaker 3
And does that include also inner duct for ducts?
00:25:14.990 — 00:25:26.630 · Speaker 1
Duct board is like a whole other topic. Yes. You're trying to figure out what is the insulating properties on average across that on the supply side and the return side of the equipment, but duck board is tricky stuff in general.
00:25:26.670 — 00:25:30.750 · Speaker 3
Is it considered like a red haired stepchild or so?
00:25:31.710 — 00:25:40.870 · Speaker 1
So the question is that red headed stepchild? Actually, Ed, I'm going to put you on the spot. Do you have any comments about duck board that you'd like to make about it being or not being a red headed stepchild?
00:25:40.870 — 00:25:42.310 · Speaker 3
I am a big fan.
00:25:42.310 — 00:25:43.550 · Speaker 7
Of any product you.
00:25:43.590 — 00:25:44.190 · Speaker 3
Prop.
00:25:44.550 — 00:25:47.870 · Speaker 7
I am basically against any product that is not.
00:25:48.190 — 00:25:48.830 · Speaker 3
Proper.
00:25:48.830 — 00:25:50.190 · Speaker 7
And I think Doug Ford.
00:25:50.230 — 00:25:50.350 · Speaker 1
Or.
00:25:50.350 — 00:26:03.270 · Speaker 7
Any kind of insulation is a perfect example. Yeah, you keep your velocities in check. It is a perfectly fine product, but you don't know what the velocity of the air traveling through it should be. Then don't use.
00:26:03.630 — 00:27:17.590 · Speaker 1
Yeah, yeah. So follow the manufacturer's specs. Install correctly. You'll be good. All right. Duct leakage. This is another really sensitive assumption in manual J. Again there's a methodology that uses visual inspection. It goes from this infiltration assumptions from totally unsealed to extremely sealed.
There's five options in between. Going from average sealed to unsealed. That at least an example of my house that that doubles the heating loads on that duct system. So pay attention to this. Again you can use your eyeballs right. Often in older homes, particularly in the northeast, we've got a lot of ductwork that are in basements.
And for whatever reason, people thought, hey, we just 50 years ago, we don't really need to bother sealing that duct work. And you can just tell you just look at the various junctions and do you see any signs of mastic? Do you see any taping of any kind? You don't see anything. I'm going to use an unsealed assumption.
Better yet, I'm going to tell the homeowner about it. I'm going to offer a service to properly seal that duct work. And ideally you're measuring the duct leakage. You're using a duct blaster. You're using the difference method to really dial this in, as opposed to using that visual inspection method to kind of figure out what is the leaking ness of the duct work.
So now we are pros in manual J.
00:27:18.910 — 00:27:40.030 · Speaker 1
Again this is a we can spend hours talking more about manual J. For me, if you're using Acca certified software. What manual? Jay like what's most important are the inputs. It's about this visual inspection. It's using these different tools to verify those inputs. And then you're going to be successful with most products.
All right. So do that thoughtful manual Jay. One more question. Go ahead.
00:27:40.710 — 00:27:41.310 · Speaker 4
So
00:27:42.790 — 00:27:49.150 · Speaker 4
manual Jay. It takes a long time to collect all that data accurately, and.
00:27:49.150 — 00:27:49.670 · Speaker 7
It takes.
00:27:49.670 — 00:27:51.590 · Speaker 4
A decent amount of time to enter it.
00:27:51.590 — 00:27:52.230 · Speaker 7
In.
00:27:53.910 — 00:27:58.710 · Speaker 4
Is there. There's been a lot of talks about using utility billing data.
00:28:00.310 — 00:28:05.350 · Speaker 3
As a way to get the load counts. What are your thoughts on that?
00:28:05.670 — 00:29:15.390 · Speaker 1
Yeah, there's trade offs with every method. There is not a standardized methodology in the United States right now for using fuels for load calques. Canada is actually working on a standard, so I'm kind of watching that to see how that might end up impacting in the US. There's trade offs of both methodologies.
There are key assumptions and errors that can happen with fuel based load calques. And I would argue with a little bit of practice. Most of the things that I just showed the most common and most sensitive variables in manual J. It takes 10 to 15 minutes to verify those details. Obviously a bit more if you're setting up a blower door test, but you should be doing a blower door test anyways for all kinds of other purposes to understand that home.
So with some practice you can verify these details. And there's big trade offs fuel based approaches. They don't work for new construction right. You have to use some kind of other process for doing the load calculations. But for me personally, I think the methodology and the thought that's gone into manual J, it is the gold standard.
There's a lot of careful thought and practice that's gone into it. And if you are using a certified product, you're being consistent, you're verifying those details. You're gonna have a lot of success.
00:29:15.430 — 00:29:20.990 · Speaker 3
Can I add something briefly to that? they can compliment each other. Is a good way to look at.
00:29:21.110 — 00:30:09.270 · Speaker 7
Using a fuel usage basis to do something. Has a lot of poles in it, simply from the perspective to explain about new constructions. How do I design the dump system based off of the BTU requirement per room? And it's a simple question how do I design a system based on all the fuel uses? I could do it for the whole home, so if you want to compare it to a block load, that's a fair comparison.
But mainly J will be do the answer for your V2 requirement per room, which can be turned into how many cfm you probably so I think they could complement each other nicely, but I don't think one is ever going to replace the other in an entirely. If somebody wants to pinpoint.
00:30:09.310 — 00:30:10.350 · Speaker 3
Things that happen.
00:30:10.870 — 00:30:11.510 · Speaker 7
Yep.
00:30:11.550 — 00:30:48.310 · Speaker 1
Great. And there's a bunch of other gotchas around this. We actually have a podcast episode that goes into this topic. Check it out. All right. Airflow and duct capacity. So we're not going to get into manual D here. What I really want to focus on is in the retrofit application you're typically you're not designing an entirely new duct system.
You're trying to figure out does the existing duct work have sufficient capacity. And if it doesn't. Are there simple things you can do to increase the duct capacity that doesn't necessarily require a full blown manual? D these are a whole other protocol. It's important you guys should learn about it, but I'm not going to get into that today.
Yeah. Go ahead.
00:30:49.070 — 00:31:03.270 · Speaker 6
So usually in a reg you're working on an enclosure. You're using the load to be the size of the BTU machine for me. So ostensibly it should be reducing the capacity.
00:31:03.310 — 00:31:06.830 · Speaker 3
So usually you're going in the direction of excess capacity.
00:31:07.070 — 00:37:52.820 · Speaker 1
Yes. So excellent comment. If you're focusing on the enclosure and you're reducing the loads on the building, that reduces the capacity you may need for that heat pump that you're probably going to put in. So excellent to work on the enclosure and improve the enclosure. You're doing permanent load reduction.
That's fantastic. And that will reduce challenges that you may run into, especially in older homes where you've got ducts that are that were not designed properly in the original home. So the key questions that we're trying to figure out in a retrofit application, the most basic. Do we have sufficient capacity to support this new equipment that we're thinking about putting in?
Probably a heat pump, and you should be testing using different methods to figure out if that's the case or not. You need to figure out whether or not you're trying to understand the most basic question, is there overall sufficient capacity? But maybe there's issues with the distribution system farther down the line.
And so you can measure had each register and figure out do I have airflow issues again with this existing equipment. Has it been pinched off somewhere. That's something we want to verify. And like I mentioned earlier, if you've got really bad duct leakage, you should test and fix those issues before you get into any of these other more significant modifications.
Because duck leakage is a big deal, there are a lot of different ways to directly measure airflow. I'm going to talk through the most basic, oldest practice, which is to measure the total external static pressure and use a fan curve. The blower curve. You just need some basic tools to be able to do this. There are some great new products out there like the tech flow grid.
It really simplifies the process. It walks you through it. It's an excellent product, so it's worth checking out. And there's some other methods. There's even some communicating controls that you can just directly read off of that thermostat. What the airflow is, what the static pressure is, because the equipment's measuring all those details.
But you need to pay attention. Make sure the coil is clean. The duct system is clean. Before you just go look at that thermostat blindly and take whatever number is off that thermostat. So what's really amazing is if you verify what the existing duct capacity is and then you go through the manual s Procedure.
You look up your equipment performance characteristics, you figure out what your design CFM is. Often for heat pumps, we need a little bit more CFM. So if we pretend in a home that we currently need about 1000 CFM at about 0.65in of water column, and you think this new piece of equipment you're proposing is going to be about 1400 CFM?
You can use fan law to just calculate what's your future static pressure going to be. And so we just do the math here. And it looks like at least in this instance, our static pressure is going to be way high. So we've got a problem. All right. We'll come back to how we figure out what that design CFM is in a moment.
But this is just simple math. We can make a forecast. One more plug for tech. They have this forecasting capability built into their product now. So you can measure with their true flow grid and use their little app to do this forecasting workflow. So it really helps instead of having to do your own little hand clicks.
All right. So let's talk about the good old fashioned way of just measuring total external static pressure and using fan curves. You just need a decent dual port manometer that can measure down to a single Pascal level. It needs to be that level of sensitivity. Those tend to be a little bit more expensive, a couple hundred dollars, but you should have one of these anyways.
If you've got a blower door rig, you've already got manometer that's probably sensitive enough. And so you measure that total external static pressure and you then look up the fan curve. So this is a hard part from my perspective, particularly for older equipment. It can be hard to track down this data in some cases.
Sometimes it's a sticker that's on the piece of equipment. Sometimes you really got to dig around to find this information. It's hard to see in this slide, but we're looking at a table here where we have first verified the Dip switches that are on the piece of equipment, which specifies what the different fan speeds might be.
And then across the right there are different static pressure numbers. And then we can just grab from our Dip switches. However they're set. We can then figure out in this particular instance that we've got 1255 cfm for this piece of equipment. So again, it's pretty straightforward. You do the static pressure measurement, you look up in the table and you can figure it out.
So what the heck is total external static pressure. This could again be a much longer conversation. But at a very high level. It's essentially the measure of resistance to airflow in that duct system. And why we care about it is that most air handlers are rated to about half an inch of water column, and fans maybe can handle up to about 0.8, generally over 0.8.
You run into trouble and you're going to have fan motor failures much earlier than expected. And if these pressures are too high, it's basically it's a measure of friction, of resistance that's in this system. And if your fan sees pressures that are too high, it just can't actually deliver the airflow.
All right. So the other tricky part about measuring a static pressure is you've got to measure in the right places and the equipment. So for a furnace. So we're assuming we're, we're swapping out a gas furnace for a heat pump. We need to measure just after the filter and right before the coil. If you've got one you take these two measurements.
We do a little little subtraction. And you can measure with that total external static pressure is if you've got an air handler it's not a furnace. You got to drill ports at a slightly different spot again after the air filter, but then after the coil if you've got an air handler. All right. So a quick example.
What's really great about these measurements is it can actually guide you. So when you look at the measurement just after the filter you look at the measurement just after the for furnace or for air handler just after the coil. Looking at those numbers, you can tell which side of the equipment. Do you have an issue.
Is it more driven on the supply side or the return side. So in this example we're actually seeing about 0.7. Of measurement on the return side. So that indicates I probably relative to my supply side measurement here. I've most likely got a more restriction on the return side. And so I can do a little bit more measurement.
I can take a probe and measure just upstream of that filter. And now I can figure out that I've actually got almost all that restriction on the return side is coming from the filter. And this is actually one of the most common areas of low hanging fruit for a home that you measure a high external static pressure, it's you've got a filter box and a filter that's just too restrictive.
You've got a one inch Merv 13 filter that's just choking that whole system. And if you can put in a nice four inch filter, that's going to make a huge difference for that equipment.
00:37:52.860 — 00:38:00.699 · Speaker 4
Yeah. So on the filters, the Alison Veils had an article about a rule of thumb for the filter size. He said
00:38:01.780 — 00:38:02.220 · Speaker 4
that.
00:38:02.460 — 00:38:03.110 · Speaker 7
Two.
00:38:03.110 — 00:38:07.700 · Speaker 4
Square feet a face area per time.
00:38:10.660 — 00:38:16.340 · Speaker 4
Not surface area. Filter media. We're talking face area.
00:38:16.380 — 00:38:16.900 · Speaker 1
Nice.
00:38:16.900 — 00:38:24.180 · Speaker 4
So if you use that rule of thumb, you understand just how underside most return.
00:38:24.540 — 00:38:26.700 · Speaker 3
Filters are there usually.
00:38:27.340 — 00:38:49.740 · Speaker 1
Yeah. Yeah. So the comment was Allison Bayles has a great article that talks about a rule of thumb where you can use the face surface area of the filter, and it's roughly you need about two square feet of face surface area per ton of cooling. And yeah, you'll when you use that rule of thumb, you'll notice that often we've got way too little surface area really restricting that equipment.
00:38:50.700 — 00:38:53.460 · Speaker 3
This filter thickness manner that.
00:38:53.860 — 00:39:55.300 · Speaker 1
Yeah. So it's somewhat counterintuitive, but typically the thicker the filter you have, the less restrictive it'll be because you're not as densely packing that filter medium. And so the thicker it is, the deeper it is, the less restriction you have. The less static pressure drop you will have. So that's why we want to get to a thicker filter.
And we'll actually have much less restriction on the system if you're keeping all other variables equal. All right. So similar example. This is where we can see the restrictions really happening at the coil. This could be because the coil is filthy. It could be I have not run this myself. But I've talked to a number of our customers.
They've come across, they've opened up a unit and they found the install manual sitting inside the unit. And that was causing a lot of static pressure, a loss there. So just do visual inspection, make sure that coil is clean. That can solve a lot of problems. All right. So now here's a proof. Now that we've addressed we've got a nice filter.
We've figured out whatever was going on with a coil. We're now in the green on the total external static pressure. Go ahead.
00:39:55.500 — 00:39:58.820 · Speaker 3
So another thing is on furnace.
00:39:58.980 — 00:40:13.140 · Speaker 4
Plus AC coil Sister, you have the static of both the furnace coil and you also have the static of the AC coil. So you already have bad ducts.
00:40:15.460 — 00:40:16.900 · Speaker 8
Going up you.
00:40:19.380 — 00:40:21.140 · Speaker 3
Could make your life worse.
00:40:21.740 — 00:42:58.620 · Speaker 1
Yep. Yeah. So having two coils, that's more restriction, more stuff in the way the airflow is going to reduce. It's going to increase static pressure. It increases friction in that system. It makes it harder for that fan to deliver those CFM. All right okay. So one slide teaser on manual D. A lot of these other opportunities to improve the duct system are just related to understanding this concept of equivalent length.
This is a great slide I actually stole from Alex Meaney. So if you imagine a duct system this is just a single supply run. We've got let's say ten feet of just straight duct coming into this nice curved elbow and then a little flex duct roughly the same length of that. This other straight duct equivalent length.
Takes into account the losses, the friction that is caused by turbulence, by changing direction of the airflow, a bunch of different factors. And so the equivalent length of this relatively nice 90 degree elbow. It's equivalent to 30ft of straight duct. And this really hard 90 degree turn doesn't have any turning vanes.
It's not rounded. This one little junction that's equivalent to 80ft of straight duct. And so if you're already addressed the filter box, you've inspected and cleaned the coil, but you're still seeing high static. You can look around for opportunities near the equipment that you can access, where maybe you can just change a couple of these fittings and you can reduce the static pressure dramatically just by swapping out even one fitting.
So simple example, if you've got a little extra space around that equipment, maybe you can put in a nice new return drop. That's got turning veins. It really helps reduce turbulence on that return. Coming to the equipment that will drop your static pressures dramatically. All right. Last thing on airflow.
Again, it's a whole other long topic. Duct leakage is really problematic, particularly in attic spaces. Not only does it cause significant energy loss through the ductwork itself, it actually creates like a double whammy. This is this topic of duct leakage to the outside, where if you have air that's leaking through the ductwork into the attic, it's actually induces more infiltration into the building.
So not only you're losing CFM, you can deliver to the home, you're actually adding loads to the building through that duct leakage to the outside. It really leads to poor indoor air quality. You get all these different cold and hotspots. If like a certain part of the supply or certain part of the return is leaking.
There can be safety hazards, all kinds of humidity issues. So just be careful with duct leakage, address duct leakage, especially in attics.
00:42:59.420 — 00:43:07.300 · Speaker 3
Sorry to be asking. Yeah, these are basic questions. I'm sorry, but do you do a manual J. Separately, perhaps in an attic. Has that ever done.
00:43:07.620 — 00:44:05.860 · Speaker 1
Manual J takes into account these different attic details for. Yeah. What's going on in the attic. How that affects whether that's the duct work or heat transfer through the ceiling. Yeah. Good question. All right. So we're pros on manual J. We're pros on measuring duct capacity. Now we can get into equipment selection.
So just reminder manual s we've got this garbage in garbage out problem. If we haven't done a thoughtful manual J if we haven't measured the duct capacity, it may be even. We shouldn't even bother with selecting equipment, right? You have no idea what the duct capacity is, or you've measured the duct capacity you've discovered.
Holy cow. We've got all kinds of different issues. You need to have a conversation with your customer before you even go further and start recommending like a whole system change out, because maybe you need to improve the envelopes. You can reduce the loads and then actually make this duct system workable.
Or maybe you need to spend a decent amount to air seal that duct work to address a bunch of different fittings before it's even even you have budget to consider equipment changes. Um, yeah. Go ahead.
00:44:05.900 — 00:44:11.860 · Speaker 4
Manual J. Does it or does it not be food duct capacity.
00:44:11.860 — 00:44:13.820 · Speaker 3
Or air duct capacity? Separate.
00:44:13.820 — 00:44:36.140 · Speaker 1
That duct capacity is its own thing. Which is why I actually wanted to spend time on it, because it's not really called out. It's not part of manual J. It's not part of manual S specifically. Right? Obviously manual D takes you through all of these details, but manual D is it's a pretty intensive process and often is really only applied if you're doing brand new duct work.
Yep. All right. So let's talk about heat pumps.
00:44:37.460 — 00:49:01.100 · Speaker 1
So there are a bunch of different performance characteristics of how we understand heat pumps. In particular we've got thermal performance characteristics. And we've got different heating capacity values at different outdoor temperatures. We've got min and max values. Same thing on the cooling side.
The companion to the sensible heat ratio is the sensible heat factor. So this is the sensible cooling capacity of the equipment divided by the total cooling capacity of equipment. And so these performance characteristics are all about comfort right. This is the ability of this system to move energy around and deliver BTUs or remove BTUs from the home.
This is what manual test is all about. Now there's some energy performance characteristics. I'm sure you're familiar with the coefficient of performance. This is the kind of foundational metric that's used for figuring out what Seer the seasonal energy efficiency ratio is for the summertime, what the corresponding HSF is.
So copy. It's just simply the ratio of the thermal output divided by the electrical input. And heat pumps are pretty amazing that for every one unit of electrical input we get two, three, four, maybe five units of thermal output. So this is about efficiency. And I've intentionally made the font really small on the efficiency side here because we really want to focus on comfort first, and generally speaking, efficiency will follow.
Now what's really interesting is manual S is completely silent on these efficiency issues. It's all about comfort. All right. So there are a lot of different performance metrics for heat pumps. But let's look at a table of data. Here we've got cooling metrics at two different outdoor temperatures. And then we have heating information at up to four different outdoor temperatures.
The tricky part is that manufacturers are not required to report this fourth most cold temperature. And they get to decide what temperature it is that they're using. So it could be at minus five. It could be at -13. It could be at five degrees. It's up to them. But hopefully you've got four different outdoor temperatures, especially if you're in a much colder climate.
And we have min and max capacity values for all of these different temperatures. So just use an example here. With the heating data at 47 degrees outdoor temperature. This particular piece of equipment this is a real piece of equipment. It has about 11,000 BTUs of capacity on its minimum operating mode, and a corresponding copy of about 3.23 at 47 degrees.
And then it's got a corresponding max capacity of about 45,000 BTUs and a corresponding copy. It's actually much higher than the min capacity. And this is actually something that's pretty common with most heat pump equipment. As you approach the getting closer and closer to maximum capacities. You actually see the highest cops.
So there's another reason why it's really important to size heat pumps correctly. Because if you massively oversize equipment, it's going to spend most of its time closer to its minimum levels, which is the lowest efficiency for that equipment. All right. Latent capacity values. These are much trickier.
And it really depends on the manufacturer what this data is going to look like. So often you'll see a table that looks something like this I know it's hard to see in the back of the room. What we've got vertically are different outdoor temperatures and across the top are different coil temperatures in indoor unit, and we can look up what's the total cooling capacity of that equipment.
But often the manufacturers will not include the latent capacity directly. They'll instead just give you the total cooling capacity and then the sensible capacity. So we have to do a little bit of math ourselves to figure out what is the latent capacity, which is just that total minus the sensible. We now have latent pretty straightforward.
I don't know why, but a lot of ductless manufacturers decide to report latent capacity data in terms of pints per hour. Good news is there's a simple conversion. There's about a thousand BTUs of latent per pint per hour of capacity. So in this example, 3.8 pints per hour, that's roughly equivalent to about 4000 BTUs of latent.
And then sometimes there can be a third kind of variation that manufacturers report the data in. It will look like table A, but instead of having the total cooling capacity and the sensible, they'll have that total cooling capacity. And then the sensible heat factor that we talked about earlier. And so we can do a little bit of math and we can figure out what that latent capacity is.
All right. So it's a ton of data. Heat pumps got a lot going on. There's a lot of different numbers. Go ahead.
00:49:02.620 — 00:49:03.260 · Speaker 3
Sure.
00:49:03.900 — 00:49:10.700 · Speaker 4
Okay so you said a minute opacity. The seal key is typically lower.
00:49:11.540 — 00:49:13.740 · Speaker 3
That is not always true.
00:49:13.900 — 00:49:18.540 · Speaker 1
That's that's right. Yep. Not always true. Most of the time it is. But it's definitely not always true.
00:49:18.540 — 00:49:24.380 · Speaker 3
Not even sometimes. So inverter heat pumps frequently.
00:49:24.380 — 00:49:42.940 · Speaker 4
Have mid toxicity. Cops are very ups. Now the caveat is you're showing that table. And that table returned from the Neat database. And the Neat database is not data is been tested or proven.
00:49:43.780 — 00:49:47.220 · Speaker 3
There's only certain numbers on there that have been tested and proven.
00:49:47.300 — 00:57:02.930 · Speaker 1
Yeah. So this is a case with manufacturer data. Most of the time they're using test data points. They do in a laboratory but they're extrapolating. And so the Neap data it's all Neap gets it directly from the manufacturers. So the manufacturers are reporting to Neap. Neap is just displaying it. But you're absolutely right.
It depends on the equipment of where those cops whether it's going to be higher or lower. And we'll get into this a bit more. What's most important here is that you need to know your own equipment, but it's not generally always going to be higher cops and higher capacities. But it often it is. Again, it depends on the manufacturer.
It depends on the particular product line. All right. So because there's all this different variation, there's so many different data points to look at. It gets overwhelming especially when you're trying to compare. Should I use this three and a half ton unit versus a four ton unit. And so it can be helpful to visualize the information.
So I like to start by visualizing the loads on the home first so you can take your. This is actually my house in the Portland Maine area. Just plot a point at five degree outdoor design temperature. I've got about 42,000 BTUs of load at that point, and then I can draw another point at about 60°F where I'm kind of assuming there's going to be no heating loads on the home.
That actual temperature varies a bit depending on climate zone and architecture, a bunch of other factors. But 60 is a reasonable place for this type of modeling. And so I can draw a line, and now I can visualize how the heating loads of the home are varying with outdoor temperature, and I can do the same thing on the cooling side.
So I've got these two lines, I've got a heating load line, I've got a cooling load line, and now I can overlay that equipment performance data for this heat pump on top of this same graph and start to get some insight about what's going on here. And so we can use those different temperatures that were reported by the manufacturer.
And we can generate this maximum heating capacity curve. Same thing on the min side. And we're doing that just using that that 47 degree outdoor test temperature or extrapolated value. We can draw this point at 45,000 BTUs. Same thing at 17, five, so on and so forth. And we can draw these curves. And so we can also overlay some information about the energy efficiency and see how that's varying.
And we can even use this information to help us understand for this particular home with this particular equipment at a certain temperature, what's the scope going to be? So I can actually look at where the line, if I draw it between the min and the max line, let's say it's 17 degrees. I can look where it crosses my load line and I can figure out, okay, roughly speaking, this piece of equipment is going to operate about a copy of 2.45 at 17 degrees for this home.
That gets to be. It's a lot of work, which is why some smart people came up with SPF. And Seer ratings encapsulate all of this variation for a typical home load profile or temperature profile, and be able to compare apples to apples between equipment. All right. So manual s it is all about Goldilocks ING equipment.
We want to be too big. We don't want to be too small. AKA released a brand new version of manual S now it's about 18 months ago. It is available for free on ACA's website. I highly encourage you to check it out. It's the only design manual that is available totally for free. At least the normative section. Just excellent that it's available for everybody to take a look at with no cost.
So right for manual S, it is really focuses on this concept of size limits to help deliver comfort for your customer. And so we're trying to Goldilocks those different performance metrics that we were talking about. The heating loads the sensible cooling and the latent cooling. What's really great about this new version of manual S, there's a bunch of changes that are really specific to heat pumps.
So there's new sizing tolerances. There's more flexibility both in wet and in dry climates. And there's even a sizing pathway for heating only if you've got dedicated dehumidifier or you're in a dry climate. So we really care about this Goldilocks sizing for a bunch of different reasons. And so I think it's helpful to talk about like what happens when we oversize equipment versus when we undersized it.
So when we oversize equipment we get a lot of short cycling, which leads to big temperature swings, has a big impact on comfort for that homeowner. When we undersized, we can obviously end up in situations where, let's say heating, we just don't have enough capacity and it could get kind of cold in the wintertime for that customer.
That's obviously uncomfortable. It can also lead to higher fan speeds. So other kind of noise discomfort, there's some interesting impacts on the indoor air quality side dramatically over sizing particularly in a humid climate. Let's say place like Louisiana. You can get some really scary issues with mold growth, right?
If that equipment is constantly cycling on and off or if it's short cycling, the equipment's not running. If the equipment is not running to actually move the air across the coil, we're not going to be extracting any moisture. And then if we're really short cycling, that coil might not ever get cold enough to actually reach dew point and pull moisture out of the air.
Interestingly, on the underside side, it's actually gonna be a good thing for indoor air quality because that equipment's going to be running almost all the time, and we're going to be moving air across that filter. Things can be really good. From a IYC perspective. Over sizing can lead to some issues with early failure of the equipment.
You're just hammering it. It's just cycling on and off. All kinds of mechanical equipment doesn't like that under sizing. It's kind of a mixed bag. And then there's obviously impacts on operational costs and install costs. If you're under sizing or over sizing. Right. So we really want to Goldilocks our equipment manual S is a very involved protocol.
There's a lot of different diagrams that kind of help you figure out what to do. The great news is if you are focused on variable capacity inverter driven heat pumps, almost all manual S simplifies into the single pathway. And it's basically this question do I have dedicated dehumidifier? Or am I in a dry climate?
Is my sensible heat ratio greater than 0.95? If that's the case, they've got this little pathway that is for this advanced dry heat pump condition. I'm not going to talk about that because most of us are in wet climates and most of us don't have dedicated humidification. So if we went on that pathway, there are four size limits that we got to pay attention to.
There's two size limits for cooling. There's two size limits for heating. So on the cooling side we've got the minimum capacity of the equipment in this the numerator compared to the total cooling load for the home in the denominator. We just want to make sure that that is less than 0.8. All right. This is kind of a way to ensure that that equipment is not going to end up short cycling too much.
And so all of these ratios, we have the equipment capacity in the numerator and the home load and the denominator. We've got a corresponding ratio for latent capacity. We want to make sure that our minimum latent that's coming from the manufacturer is more than 100% right. We're covering we can deal with all that latent load heating side.
Same kind of thing. We're looking at that minimum capacity of the equipment divided by the total heating load of the home. And then the similarly to the latent capacity, we wanna make sure we have 100% capacity of that equipment relative to that max load on the home. Go ahead.
00:57:03.090 — 00:57:05.090 · Speaker 4
Min Lake capacity.
00:57:06.170 — 00:57:10.490 · Speaker 4
I've never seen a company list that's. Or maybe 1 or 2.
00:57:10.610 — 00:57:30.370 · Speaker 1
Yeah. The common is that how do we find min latent capacity? This is a huge issue with manufacturers. I encourage folks talk to your distributor, talk to your manufacturer. Ask them for this information. It can be a real challenge to find this data or find any latent capacity information at all. So this is a big issue.
00:57:30.450 — 00:57:31.530 · Speaker 3
It reflects negatively.
00:57:32.010 — 00:57:48.010 · Speaker 1
I don't fully understand why this is not something that Manufacturers kind of make it easier for us to look up, because it's such an important part of the design process. Anybody has ideas of ways to change this, but it is a real challenge in the industry in general that we just it can be really hard to find this information.
00:57:48.050 — 00:57:52.250 · Speaker 4
We have lost a lot of weight capacity to Trans
00:57:53.370 — 00:57:56.130 · Speaker 4
Seer two and HSF two.
00:57:57.290 — 00:58:11.929 · Speaker 4
The race for higher of those two numbers results in coil designs that have huge coil surface areas, so you can get higher efficiencies, but your coils never get close
00:58:13.570 — 00:58:15.250 · Speaker 4
and you coils never get cold.
00:58:15.250 — 00:58:16.770 · Speaker 3
You don't get very good late.
00:58:17.170 — 00:58:41.850 · Speaker 1
Yeah, there's no free lunch. If you have slightly warmer coil temperatures, that means you get higher efficiency, but you have lower latent capacity. Generally speaking, all things being held equal. So this is why it's more important than ever for us to get access to this latent capacity information, so we can help figure out what's the right equipment for the home.
All right. For anybody. Eagle eyes back there. There's a little asterisks on all of these little capacity values. Go ahead.
00:58:43.330 — 00:58:44.850 · Speaker 3
0.8. Why? Why?
00:58:46.170 — 00:59:13.650 · Speaker 1
That's a great question. I was not part of the manual ethics committee. That kind of ultimately led to that decision. I'm going to put out an editor. Just took off. If anybody else knows why we landed on 0.8, please shout it out. I don't know what answer to that. I'm actually I'm curious myself, have been trying to dig into public comments around it, but I think it ended up being a value that for most equipment and most scenarios, it just made sense.
It was a reasonable constraint to put on the equipment.
00:59:14.290 — 00:59:14.850 · Speaker 3
Yep.
00:59:14.890 — 00:59:16.170 · Speaker 5
Um, I'm going to see.
00:59:16.170 — 00:59:16.410 · Speaker 3
For.
00:59:16.450 — 00:59:16.930 · Speaker 5
Like.
00:59:16.970 — 00:59:30.170 · Speaker 9
A lot of us who are new minimum capacity compared to total load. Can you give me like a real simple why? And what is it? You know what I mean. Not. Not what? Minimum capacity. But, yeah. Could it be better at this point?
00:59:30.730 — 01:00:32.770 · Speaker 1
Yes. So I will show some more information in a minute. That'll help kind of bring it to life. It's an excellent question. So like, how do we understand why this min capacity versus total load is important and how it plays out for low load cycling is where it really shows up. But the really important thing here, there's this little asterisks on all these capacity values.
This is that operating conditions of the equipment. This means we have to take into account both the design temperatures. So what's that outdoor temperature that the outdoor unit is experiencing. But we also need to correct for other things like altitude. Right. If you're in high elevation Colorado, that equipment capacity is going to just be reduced from fundamental physics because of that, that high altitude.
There also line set length D rates. So if you got a really long run of refrigerant line that reduces the capacity of the equipment. Similarly, again depending on the manufacturer you can have multi zone D rates. So you need to take into account all of these different factors. Use that capacity in your manual S.
All right. So the math is pretty straightforward.
01:00:34.490 — 01:03:36.970 · Speaker 1
Since these four ratios, what was really hard about manuals is what we already started talking about. It's hard to find the data. It should be available in your manufacturers expanded or extended performance tables, but it can be hard to track these down. Sometimes they're behind a sign in wall, or you have to work with your distributor in order to define the information, but it should be the most granular.
It should have the latent capacity values. For whatever reason, I have come across a number of manufacturers, even though there are other places where you can find the coldest performance value for the equipment, the manufacturer itself doesn't report it in its own tables. So the good news is Neap, which we also talked about briefly a few minutes ago.
This is a great resource. If you're not familiar, you can see the URL right here on the slide. It's a searchable database. It is the best single resource I have found for heat pumps. It has the most coverage for these min and max values at the most number of temperatures. The challenges that doesn't have any latent capacity data.
They are working on this. Actually, Ari has decided that for the first time to include latent capacity for the equipment as part of their the testing requirements, but it's still going to take a while for that to kind of flow through and become available. And its HRC numbers are only going to have one number as opposed to at different fan speeds, different operating conditions unfortunately.
All right. So let's how do we figure out what is the correct design airflow for a piece of equipment. All right. So we've done our manual J. We've verified what our duct capacity currently is. And now we're looking at a piece of equipment that we know. And we're trying to figure out what design airflow do I need.
And so I can then compare that to my duct capacity. So they have similar tables that we looked at earlier. I know this is hard to read in the back there, but basically again across the top we've got different indoor conditions. So what's the entering air conditioners going over that coil along this kind of these vertical columns.
And then horizontally, we've got different outdoor across the top and indoor in the rows. And so from that we can just look up in this table. They actually list what is the necessary CFM that this equipment needs to be operating at or can operate at in order to deliver, in this case in heating mode, a 56,000 BTUs of capacity.
What's really tricky here is that there are different settings that are available for the equipment. This is the same piece of equipment and you just changing a dip switch. You can set it to operate in comfort mode versus efficiency mode. And so if you pay attention here, what I previously showed was about same capacity but a very different airflow.
So in comfort mode it's we only need about 1500 CFM. And in an efficiency mode we need almost 2000 CFM. So this is another kind of bag of tricks. Depending on your manufacturer, the equipment you're installing, you might have this option to change the settings of the equipment so that you can work around some of these duct capacity issues potentially.
All right.
01:03:38.290 — 01:03:40.090 · Speaker 3
So efficiency mode.
01:03:40.530 — 01:03:46.610 · Speaker 4
Tire fan speed almost no lady removal comfort lower.
01:03:46.610 — 01:03:50.530 · Speaker 3
Fan speed. You have some blade removal. Yep.
01:03:50.570 — 01:06:19.890 · Speaker 1
It all depends on the equipment. Yeah. It should listen those tables. What the latent capacity values are in these different operating modes. And so if you have relatively low latent loads in the home, maybe you can get away with operating in efficiency mode, but maybe not. Maybe you need to operate in comfort mode because you've got higher latent loads and you need to remove more moisture.
The last thing that tricky part about manual S is that there are kind of two different approaches. If you meet kind of what they call their default requirements, where you can just use these typical assumptions for the indoor, for the temperature and conditions of the air that are going over that coil.
You're good to go. You can just go straight to the OEM table and you can look up some information. If you've got ventilation that is bringing outdoor air and returning it and bringing that into the return side of the duct system, or you have worse than average duct leakage. You need to use a special little protocol where we adjust the assumptions around what that entering air temperature is that's going over the coil.
And this kind of makes sense. Like if you've got outdoor air being brought in right before it goes across that coil, it's going to increase that temperature or decrease that temperature, maybe increase the humidity or decrease the humidity of that air. And so after you look up these values, so we already had measured our duct capacity.
We now have a design airflow. And how we can just compare that those two numbers. And we can know hey we're in good shape or actually you might have a problem. All right. One other wrinkle. So we have all this manufacturer data, these tables there are lots of kind of absorb if you're the first time you're looking at them.
But let's say your outdoor design temperature is nine degrees Fahrenheit. But the data that you're looking at all that's available are temperatures at five degrees and at 17 degrees. So you have to do some interpolation between these values to figure out, okay. At about nine, where are we between these min values, these max values.
You need to do this for all of the cooling capacities as well. It's a bunch of math and it's tricky and it's error prone. It's a real pain. So the good news is we have a free spreadsheet tool that helps you with almost all this interpolation with follows the manual S protocol specifically for variable capacity equipment.
You can take a picture of the QR code and download it. It also has an option in here to help you size dual fuel, and it'll also help you figure out auxiliary heat needs as well.
01:06:21.210 — 01:06:21.850 · Speaker 1
Yeah.
01:06:23.450 — 01:06:25.330 · Speaker 3
Defrost here.
01:06:26.770 — 01:06:27.770 · Speaker 3
You talk about that.
01:06:28.170 — 01:06:50.690 · Speaker 1
So the question is. Defrost rating varies by the manufacturer, but in their performance characteristics they should be taking into account defrost. But it does vary. You need to look at the fine print. Often in these tables you'll see a little footnote around the heating capacity values of what exactly they're doing, what assumptions they're making, or what's incorporated in the table.
So it's another important detail to pay attention to. All right.
01:06:52.290 — 01:06:56.410 · Speaker 1
Any questions before I move to the next section we're getting close to wrapping up here. Go ahead.
01:06:57.610 — 01:07:00.090 · Speaker 3
Ask you to go back to this slide. Yes.
01:07:00.130 — 01:07:06.930 · Speaker 1
Was this one. Oh this guy. Yes. Sorry. Yeah. Yeah.
01:07:06.970 — 01:07:08.490 · Speaker 6
So mid.
01:07:08.490 — 01:07:10.370 · Speaker 3
Late 80s like.
01:07:10.810 — 01:07:13.650 · Speaker 6
The total street money he planted on the market.
01:07:14.130 — 01:07:22.530 · Speaker 10
Uh, they crashed and burned in the consumer expectations and hence took like a decade or two decades and back.
01:07:22.930 — 01:07:38.130 · Speaker 6
So my empirical observation of satisfaction blows over any parts of the house. Is a lot of frustration on the consumer. And I was setting ourselves up particularly because in skyboxes, because a lot of people don't find.
01:07:38.130 — 01:07:42.090 · Speaker 3
It fun and it's just not happening. So just push it.
01:07:43.010 — 01:08:45.330 · Speaker 1
All right. So you there's a lot you've made comments about. I'll try to recap. So your first point was that this is not the first round of heat pumps. I would actually argue this is like electrification 3.0. So like 1.0 was it was way back in like rural electrification. And then 2.0 was. Yeah, kind of like the into the 80s time frame.
And now we're to 3.0. I think there's a lot of smart people have thought about this concern, this issue, this challenge. I think we're in a much better position this time around to be successful. The technology is advanced dramatically, like the actual equipment itself. The knowledge level is so much higher.
Our diagnostic tools are so much better. We've got new software products that can help make a lot of the stuff easier. It is definitely complicated, and I don't want to pretend that this is like easy to do. But there are some simple things you can do that make this process much easier and more accessible, and will lead to good outcomes for contractors and for homeowners.
01:08:46.330 — 01:08:52.210 · Speaker 6
Three things I observe litigation are cost version uncertainty.
01:08:52.290 — 01:08:52.970 · Speaker 9
Yep.
01:08:53.290 — 01:08:54.890 · Speaker 6
I see all three here.
01:08:55.569 — 01:08:56.290 · Speaker 3
So I guess.
01:08:58.290 — 01:09:49.890 · Speaker 1
You're more pessimistic than for me. It's really important to talk about this stuff to like make sure everybody's aware of these different challenges when it gets down to it. It is definitely hard if you're this is the first time you've ever been exposed to this information. It's overwhelming. What you'll find is after you've had a few revs on it, you've gotten comfortable with looking up this data, you understand these different diagnostic tools that are available to you, and you've applied them in the field a few times.
You actually like it starts to kind of come together. And particularly the manufacturer data, it can be really hard to track it down. But if you just save it somewhere, you write it down somewhere, you put it in a spreadsheet, then you don't have to do all this legwork to look it up again. Most people are installing this roughly the same equipment for most projects, and so we're talking about like 5 to 10 different pieces of equipment.
You need to just write down and then you have it at your fingertips.
01:09:49.930 — 01:09:53.130 · Speaker 3
Yeah I agree with everything you said.
01:09:53.930 — 01:10:08.210 · Speaker 6
But I think the manufacturers aren't controlling the delivery chain delivery of their product. And we're getting lots of bad examples of outcomes. And so where the manufacturers have to step in and kind of control.
01:10:08.210 — 01:10:09.010 · Speaker 5
Quality for.
01:10:09.010 — 01:10:13.130 · Speaker 3
This, what variation of that outcomes came. Right.
01:10:13.570 — 01:13:21.600 · Speaker 1
Yeah. So I mean ultimately I think what you're getting at is that like the heat pump revolt of 2026 or 2027, is going to come from all kinds of bad outcomes for homeowners in particular. Right. So if you have a bad experience, you usually tell ten people about it. If you have a good experience with something, a good product, a good service, usually tell like a couple of people about it.
And so those bad experiences really stick out and get spread much more quickly. So it is very important that we have good outcomes in order for this to work out for everybody. That's why I'm doing this talk today. I want there to be good outcomes. I want everybody to successful. I want this to to work out. All right.
So let's get into a few more details. This is where we're going to bring all these different trade offs together and wrap things up. So manual S has these guardrails we just talked through. But there's actually quite a bit of room still to really dial in that system. And it comes down to things like auxiliary heat.
This issue of low load cycling, which you asked about will we're now day into the airflow issues and efficiency. We're not going to get into system layout. We're not going to get into commissioning and installing the equipment. That's a whole other topic. So let's come back to these curves. This is a real piece of equipment.
And what's happening when we're in this kind of green shaded area where the home loads are kind of between these min and max curves. It's good. This is green is good. This is the happy zone for heat pumps. This is where we're modulating that variable capacity equipment. It's able to exactly match the loads the home is experiencing.
All right. Things get more challenging when we're in this upper left where we have the home. Loads are above the maximum capacity of that equipment. The little crossover point. This is our balance point. Our thermal balance point where the equipment is not keeping up. And we might need some auxiliary heat.
Manual S says we only need to have enough auxiliary heat to meet design temperatures. It is optional to have enough additional capacity to kind of go beyond that. I generally recommend going a little bit beyond it, just as a comfort and emergency heat situation, it means at least if you've installed a heat pump, you're relying on auxiliary heat strips.
If that compressor fails you, it's not an emergency situation. You're not worried about pipes freezing in a home, like they'll at least be able to limp along for a little bit of time. You can kind of figure out how to fix the issue. And then down in the lower right here, we've got low load cycling. So this is where the equipment minimum capacity is above the loads of the home.
So this is what you were asking about earlier. And this is something we also want to pay attention to. And it's what these 0.8 sizing factor is kind of trying to drive at. So if you don't meet that 0.8 requirement, you're going to have severe low load cycling is what that manual threshold is all about. All right.
So what's really fun is you can actually quantify what these little shaded areas correspond to in terms of hours a year. So if you overlay temperature bin data. So this is for my house in the Portland Maine area. I can actually calculate that I will need about 200 hours a year of auxiliary heat for a typical year.
01:13:23.160 — 01:13:24.320 · Speaker 1
Yeah, yeah.
01:13:26.200 — 01:13:30.120 · Speaker 1
In this particular example, it's only a couple of KW. Yeah. Yeah.
01:13:30.160 — 01:13:30.520 · Speaker 3
Yep.
01:13:31.240 — 01:14:37.720 · Speaker 1
Yep. And then, then the low load cycling in the heating season, about 14% of the time I will be in the low load cycling zone and the cooling side for this particular piece of equipment, I'm going to be low load cycling almost 37% of the cooling season. So that's something I know you want to pay attention to.
So what's really fun here is that this piece of equipment that I've been showing you so far, it's a four ton, really top brand, cold climate style heat pump. It's an excellent piece of equipment, but I'm going to overlay two other manufacturers. Again, these are top brands out there of different sizes.
So here's the three and a half ton unit. I'll do that one more time. So this smaller piece of equipment actually has significantly more heating capacity than the quote unquote, larger piece of equipment. I'll overlay one more. I'll do a three ton unit, totally different curve. This three ton unit, it actually has more heating capacity at design temperature than the four ton, but then drops off at warmer temperatures.
And now here's all three pieces of equipment overlaid here.
01:14:37.720 — 01:14:40.400 · Speaker 3
So you're getting these points from the heat database right.
01:14:41.160 — 01:14:44.640 · Speaker 1
These are coming from Neap database which is coming from manufacturers.
01:14:44.720 — 01:14:50.840 · Speaker 3
Yep yep. Like I said we will you get away from 4717.
01:14:50.840 — 01:14:51.040 · Speaker 4
And.
01:14:51.040 — 01:14:51.800 · Speaker 3
Five.
01:14:52.440 — 01:14:53.040 · Speaker 7
Which are.
01:14:53.040 — 01:14:56.600 · Speaker 4
Rated by you max or min necessarily.
01:14:56.640 — 01:15:02.000 · Speaker 3
Yep. You start plotting and then those are not proven numbers.
01:15:02.160 — 01:15:10.560 · Speaker 1
That's right. So much of the performance data in manufacturer's tables are interpolated or extrapolated from these test points. Yep.
01:15:10.920 — 01:15:13.480 · Speaker 3
So you might not actually get them in real life?
01:15:13.720 — 01:15:14.080 · Speaker 4
Sure.
01:15:14.120 — 01:15:16.800 · Speaker 3
I get more. Yeah, you might get more. More.
01:15:16.800 — 01:15:17.680 · Speaker 9
The oversize of it.
01:15:17.680 — 01:15:27.839 · Speaker 4
The factories might get more. You might get luck sake. The controls are not late. Maybe not be there to achieve those. Those modulations here or
01:15:28.960 — 01:15:30.800 · Speaker 4
because of extrapolation.
01:15:31.840 — 01:15:32.840 · Speaker 3
You might not get them.
01:15:33.040 — 01:17:20.840 · Speaker 1
All right. So let's look at these different pieces of equipment. We can also look at airflow. So these different units have different airflow requirements. So you can see a couple of them with using the fan lock two. We can forecast that we're going to have some static pressure issues. Again this might be an opportunity to address that ductwork and reduce static pressure.
And then we can look across all these different pieces of equipment. Turns out all three of them are manual S compliant. But they have very different characteristics around these low load cycling their needs for auxiliary heat. This is driving different energy efficiency characteristics. And so I'll just jump to the punchline here.
We can model what's the electricity consumption. This three ton unit consumes the least amount of electricity. This is including the need for auxiliary heat. In this particular example, utility rates obviously change the impact of costs for that homeowner. So we're obviously we care about how much energy is being consumed.
But the actual cost to the homeowner can really depend on what the electricity rate they're on. So if they're in a place like Maine or New York or even Massachusetts or other parts of the country, now have heat pump specific rates, even though that three ton unit is a lot more energy efficient from a cost perspective on an annual basis, we're only talking about like a $70 difference, so it might not matter that much again, depending on your particular utility, but depending on the particular home or equipment you're using.
All right. So now we can look across all of these different characteristics. And so the real question is which one of these pieces of equipment are the best for this particular home? Anybody want to take it. Take a hack at it. Okay. It's the small one. Why?
01:17:22.440 — 01:17:22.680 · Speaker 1
Okay.
01:17:25.000 — 01:17:31.000 · Speaker 1
Okay. Any any other thoughts? Why? The three ton is the best piece of equipment for this home?
01:17:31.080 — 01:17:33.320 · Speaker 3
Got more green letters? Okay.
01:17:34.560 — 01:17:36.440 · Speaker 5
You know, I'm not to.
01:17:36.440 — 01:17:37.160 · Speaker 9
Do with the size.
01:17:37.160 — 01:17:37.960 · Speaker 5
Of the old.
01:17:38.560 — 01:17:43.880 · Speaker 9
That you give an older size when it can't actually express.
01:17:44.320 — 01:17:44.920 · Speaker 6
Itself.
01:17:44.920 — 01:17:45.560 · Speaker 9
Properly.
01:17:45.560 — 01:17:46.400 · Speaker 6
And the c.
01:17:46.440 — 01:17:54.760 · Speaker 9
Yep. Can't do all the punches they're supposed to do. Yep. You can't run it. That little thing working all the time.
01:17:55.760 — 01:18:00.320 · Speaker 5
Because I figure you machine. You get the job done really fast.
01:18:01.200 — 01:18:02.000 · Speaker 1
Yep. Yep.
01:18:02.000 — 01:18:02.760 · Speaker 3
That's used.
01:18:03.960 — 01:20:27.040 · Speaker 1
Yeah, it's definitely part of it. Yep. All right. This is a trick question. There isn't necessarily a perfect piece of equipment. It actually depends on a bunch of these other factors. What are the needs of the homeowner specifically? What are the other technical constraints of the home? What's the budget?
Maybe these pieces like this three and a half ton unit. It's got some challenges with static challenges with airflow. Well, maybe it's super easy to change out the filter and reduce that static pressure. Then all of a sudden it goes into the green. Maybe the home has a 100 amp panel, and it's going to take six months for the utility to come out to install a new service, drop and upgrade that panel to 200 amps.
And so maybe auxiliary heat is not an option at all. Right. There's just not enough capacity in that home to do that. And so the three and a half ton is a better option because it doesn't necessarily require any auxiliary heat. Or maybe you're able to improve the enclosure and reduce the loads overall. And then all these equipment could be considered as an option.
So it depends on the each individual home. It depends on having this conversation with the homeowner. What I encourage is folks to kind of present some of this information to the homeowner, depending on what's going on, and help empower them to make decisions, and that will lead to great outcomes for you that will lead to great outcomes for your customer.
All right, so just to completely wrap things up, I am under no expectation that folks are going to be making these custom graphs. Meep thankfully does this for you so you can build these kind of charts. They have temperature bins. They have all this manufactured data. They will calculate how much auxiliary heat, how many hours per year you might need.
Same thing on the cooling side in terms of low load cycling. It's an excellent tool. So I encourage you to do thoughtful manual load calculations, verify those key assumptions. Use some of these tricks that we mentioned and you're going to be successful. Measure the duct capacity. Don't bother going through all this process.
If you have ducks that are just way too small, right? You're going to run into all kinds of challenges. Document the manufacturer data for the equipment that you install. There's probably about ten pieces of equipment that you're installing most often. Just write those down, save them in a spreadsheet.
You can use them over and over again. And yeah, if you really want to dig into it, check out the air source heat pump database. All right, that's it. Thanks, everybody.
01:20:30.200 — 01:20:52.640 · Speaker 1
Thanks for listening to the Heat Pump podcast. It is a production of Amply Energy and just a reminder that the opinions voice were those of our guests or us, depending on who was talking. If you like what you've heard and haven't subscribed, please subscribe in your favorite podcast platform. We'd love to hear from you, so feel free to reach out! You can reach us once again at hello@amply.energy. No .com just energy. Thanks a lot.