To watch a video version of this podcast, click here: https://youtu.be/eK-WIS7inMU
In this episode, Reuben Saltzman and Tessa Murry talk with Steve Rogers, President of The Energy Conservatory (TEC), about the science behind home performance and why so many HVAC systems fall short of expectations. Steve shares TEC’s journey from early prototypes to industry‑standard testing tools and explains how comfort, moisture, and efficiency issues often stem from the building envelope. The conversation dives into blower doors, airflow testing, duct leakage, furnace short‑cycling, restrictive filters, oversized systems, and the key measurements inspectors and homeowners commonly miss, offering practical insights for homeowners, inspectors, HVAC technicians, and building‑science enthusiasts alike.
You can check out The Energy Conservatory website here: www.energyconservatory.com
Takeaways
TEC manufactures tools that measure building airtightness, duct leakage, and airflow—core metrics for diagnosing home performance issues.
Blower door testing became essential because leaky houses waste energy, cause comfort issues, and contribute to attic moisture problems.
Early blower door prototypes were expensive and slow; TEC revolutionized the field with affordable, efficient models.
Airflow is one of the hardest HVAC metrics to measure accurately; TEC’s TruFlow Grid helps techs commission systems properly.
Most furnaces and ACs are never tested for correct airflow after installation, which leads to early equipment failure and poor efficiency.
High temperature rise = low airflow. This often causes the furnace to hit its high‑limit switch and shut off prematurely.
Oversizing is rampant—many homes have furnaces 1.5–2× larger than needed, increasing noise, inefficiency, and comfort issues.
Filter restrictions depend on pressure drop, not just MERV rating. Pleat depth and surface area matter more than the number printed on the label.
3M Filtrete filters maintain reasonable pressure drops because they add pleats as MERV levels increase.
The most important starting point in energy upgrades is a blower door test, not HVAC replacement.
Older homes—especially balloon‑framed houses—are extremely leaky and need targeted air‑sealing.
Complicated house shapes (L‑shaped, multi‑level splits, many dormers) are typically leakier than simple rectangular designs.
Many contractors still do not measure airflow or static pressure, causing repeat callbacks and inefficiency.
TEC’s tools and apps help HVAC techs commission systems properly—reducing callbacks and improving system performance.
Homeowners can access subsidized energy audits through utilities, often including blower door and infrared inspections.
Chapters
00:00 — Introduction and Guest Welcome
02:00 — Steve’s Background & The Origin of The Energy Conservatory
05:00 — How Blower Doors Were Invented & Early Challenges
08:00 — Engineers, Inventors & TEC’s Company Culture
11:00 — Advances in Airflow Testing: TruFlow Grid Explained
15:00 — Why Airflow Is Critical for Furnace & AC Efficiency
17:00 — Temperature Rise, High‑Limit Switches & Furnace Cycling
20:00 — Common Installation Issues & What Inspectors Should Look For
22:00 — The Truth About Furnace Filters & Pressure Drop
26:00 — Oversizing Problems & Proper Equipment Matching
31:00 — Why Most Homes Have Comfort Problems (and How to Fix Them)
35:00 — Blower Door Testing as the First Step in Home Performance
38:00 — Moisture, Attic Frost & Air Leakage Pathways
41:00 — Styles of Homes That Tend to Be Leakier
44:00 — Balloon Framing vs. Platform Framing
47:00 — Why the Industry Changes Slowly & The Role of Training
52:00 — How Homeowners Can Learn More & Access Energy Audits
53:00 — Closing Thoughts and Resources
TRANSCRIPTION
The following is an AI-generated transcription from an audio recording. Although the transcription is mostly accurate, it will contain some errors due to inaudible passages or transcription errors.
Reuben Saltzman: Welcome to my house. Welcome to the Structure Talk podcast, a production of Structure Tech Home Inspections. My name is Reuben Saltzman. I’m your host alongside building science geek, Tessa Murry. We help home inspectors up their game through education, and we help homeowners to be better stewards of their houses. We’ve been keeping it real on this podcast since 2019, and we are also the number one home inspection podcast in the world, according to my mom.
Reuben Saltzman (00:01.494)
Welcome back to the show Tessa great to see you at all as always man. I’ve got some stories to share I got some stuff to lament about but we’re gonna have to save it for another day because I could take up the whole show on this one, but We got some talk in the new at some point here And I’m gonna I’m gonna be throwing things but it’s fine Well, we’ll come back. I’m teasing it. I’m teasing it
Tessa Murry (00:13.932)
Okay, I’m excited.
Reuben Saltzman (00:28.066)
But we’ve got a special guest on today. Today we’ve got Steve Rogers, who is the president of the Energy Conservatory here in Minneapolis. Steve, thank you so much for coming on the show today. How you doing?
Steve (00:41.901)
Good, I’m happy to be here.
Reuben Saltzman (00:43.544)
Good, good. Well, Tessa, why don’t you give your version of an introduction for Steve and then we’ll let Steve talk about his background a little bit. How does that sound? Because, yeah.
Tessa Murry (00:55.468)
That sounds great. That sounds great. Well, I first met Steve just, what was that, a couple years ago, Steve, when I was helping teach at the U of M building science class. And one of the field trips we took was to the Energy Conservatory. And you were there and you were kind of showing the class some of the things and the equipment. But I want to hand it over to you to introduce both yourself so our listeners can hear a little bit about you and how you got to where you’re at today.
And then also kind of explain a little bit about what the Energy Conservatory is and what you guys do for those that don’t know. So, Steve, take it away.
Steve (01:32.589)
Yeah. Okay. My name is Steve Rogers. I’m the president of the Energy Conservatory, as Ruben said, and the Energy Conservatory is a manufacturing company. And what we manufacture is equipment for testing buildings and it’s used for both, you know, residential buildings and larger commercial buildings. And specifically we’re testing how airtight buildings are. And it turns out that in most of the states in the United States now, a newly constructed house has to meet a certain
air tightness requirement. And we also make equipment to measure how airtight duct work is. And in many states, there’s code requirements around how airtight the duct work has to be for your heating and cooling system. And we also make equipment that measures airflow through the heating and cooling system. And that’s kind of our niche is measuring pressure and airflow and leakage, which are all kind of related.
Tessa Murry (02:17.107)
you
Steve (02:31.673)
If you dig into the science and me personally, I came to work for the energy conservatory in 2015, had some career changes. And then in 2017, I bought out the founder of the company. He’s still with us, still works with us every day, but you know, he works when he wants to unlike their yeah. Gary Nelson is the founder of the energy conservatory. And so I bought the company in 2017. I brought my partner, Bill Graber on.
Tessa Murry (02:51.574)
Gary Nelson, right? Yep.
Steve (03:00.697)
in 2019 and the two of us are the co-owners of the Energy Conservatory. There’s really only two companies in this space and we’re the only company that’s US owned and operated. So my background is in engineering and I’ve done measurement of pressure and flow for probably close to 30 years now. I started for an instrument company that’s in the Twin Cities area.
They do the similar kinds of measurements, but in a completely different industry, they’re in industrial process control. So they make instruments for refineries and pulp and paper mills and power plants and that kind of stuff. But it turns out, you know, the physics is the same, even if the instruments are different. So, so that’s who I am. That’s what we do. And my background is as a, you my education is as a mechanical engineer and that’s the
Tessa Murry (03:49.27)
Yeah.
Steve (04:00.973)
the curse that I’ve carried for a long time. But that’s just how my brain works.
Reuben Saltzman (04:04.75)
you
Tessa Murry (04:09.386)
gonna say Steve is being very humble. He’s one of the most like brilliant engineers I think I’ve ever come across. And also I would have to say I am so impressed by just the team at the Energy Conservatory. You guys are such a know such a unique and impressive mix of both engineers and creators and inventors and designers and physicists. Some of the smartest people I know and I just think it’s really cool you know you said you’re
TEC is one of two companies in this industry, which blows my mind because you think about all the buildings being built across the country, houses and commercial that are being required to be tested and you can buy basically a blower door or this testing equipment from either TEC or this other company, which shall not be named.
Reuben Saltzman (04:43.138)
Yeah.
Steve (04:58.987)
Yeah, most people who have used our equipment when they come to meet us or they come to see the company or they meet us at a show and like, hey, how big is your company? You know, and we’re around 25 people and they’re like, really? That’s all they thought. They think we’re a company of hundreds of people. And it’s the analogy that I’ve used is we make the tools. There’s way more people doing this testing than there are building the instruments. So it’s not it’s not a question of like how many
Tessa Murry (05:12.074)
That’s it.
Steve (05:29.049)
barbers and cosmologists, cosmetologists, does it take to cut hair for a population? It’s more like how many scissor manufacturing companies does it take to make the scissors for the people cutting hair? So it’s a little bit, it’s a couple steps removed from the people doing the building and doing the testing, the people that are manufacturing the instruments, which lasts a long time, right? You so you buy one blower to our system and we’ve got blower to our systems that have been
Tessa Murry (05:39.212)
Yeah. Yeah.
Reuben Saltzman (05:40.675)
Sure.
Tessa Murry (05:52.864)
Mm-hmm.
Steve (05:56.609)
in use for 20 and 30 years. It’s very common. And so that’s why we’re not as big as people think. We’re a couple of steps removed from construction or even testing the construction because we’re manufacturing the tools that they use.
Tessa Murry (06:01.056)
Yeah.
Reuben Saltzman (06:12.269)
Yeah.
Tessa Murry (06:12.272)
When did Gary start the company? Is that back in the 70s or 80s? Okay.
Steve (06:17.489)
Early 80s. I think 82 and I think there was you know some work going on before it was incorporated but I think it seems like 82 or 83 is when it was incorporated. Yeah.
Tessa Murry (06:24.694)
Okay.
Reuben Saltzman (06:26.382)
What was he doing back then when he started the company? What was your big focus?
Steve (06:30.377)
So Gary was working for the Minnesota Energy Office, which is the precursor to it. The department has a different name today, but he was involved as he got he studied physics and engineering and he got a job trying to figure out energy efficiency because this was right as the the first energy crisis happened in the early 70s or mid 70s. And
Reuben Saltzman (06:35.896)
Okay.
Tessa Murry (07:00.108)
Mm.
Steve (07:00.241)
so he was aware that a blower door was a thing, but before he started the company, a blower door was something that costs tens of thousands of dollars. And to do a blower door test would be like half day, all day project to measure how airtight a house was. And Gary couldn’t afford one. He’s like, well, maybe I could make one. cause that’s just the kind of person that Gary is. And he said he, right.
Reuben Saltzman (07:16.856)
Sure.
Tessa Murry (07:23.734)
He’s your kind of guy, Ruben.
Reuben Saltzman (07:25.186)
Yo, absolutely, I love it.
Steve (07:27.097)
And so he’s like, made, he’s like, maybe my first prototype, then it didn’t work at all. And I made a second one and it kind of worked. The third one worked really good.
Reuben Saltzman (07:35.65)
I’m picturing a box fan and poly and lots of duct tape.
Steve (07:39.513)
I haven’t seen the first prototypes we have in our our Bloor Door Museum here. We have model one, model two and model three and kind of the evolution. But before model one, I’ve never seen prototypes. But yeah, and so and as soon as he had done that and found something that worked pretty good, know, people that he knew at the energy office and then people in other states started asking, hey, could you make me one? Could you make me one?
Reuben Saltzman (07:51.736)
Okay.
Tessa Murry (07:53.078)
Yeah, that’s amazing.
Steve (08:06.805)
And, you know, because he had figured out how to do it for not tens of thousands of dollars and it could be done in, you know, an hour instead of all day. You know, everybody wanted one and it just grew from there.
Tessa Murry (08:18.56)
Wow, that’s amazing. Yeah. And you guys have this team now of engineers and inventors, I feel like, that are constantly kind of just in tune with the field and the people that are doing high performance testing, diagnostics, and trying to figure out what’s going on and how to fix things. And they come to you guys and your team, and you figure out how to measure it and how to build equipment to answer those questions, including apps and everything.
Steve (08:47.245)
Yeah, yeah. So, and I kind of walked into the, you know, the nerdy team. Most of them, you know, were, been around long before I was on board, but Bill and I have tried to, you know, continue to cultivate that culture and that team. We do have an amazing culture. I can’t take a lot of responsibility for that other than like, let’s keep this going. But yeah, yeah, exactly.
Tessa Murry (09:05.356)
You fuel them with coffee and beer that’s on tap in your break room, right?
Steve (09:13.209)
But we’ve been out in the field since the early, early days. Gary was in the field measuring homes when he worked for the state energy office and continued that, learning about how to do tests and how do I do a multi-fan test? That’s quite a bit more complicated. If I’m doing a big building, I might aid 10 different fans and how do I make them all work together? And so that culture really
connects with the name of the company too. We have a weird name, the Energy Conservatory. Most people listen to that and they’re like, the what? And you have to know there’s like an inside joke there and that is that Gary, there was another founder. So Gary Nelson is the one that’s still with us. Gary Anderson was the other founder. So there were two Garys that founded the company and they were both musicians. And they imagined when they started the company that they wanted to create an energy conservatory.
Tessa Murry (09:47.082)
Thank
Steve (10:08.867)
which would teach people about saving energy, like a conservatory of music teaches people about making music. And so that’s kind of the play on words. That’s like the nerd background of these, these guys were into, you know, saving energy and they were energy nerds, but they were also both musicians. and yeah, and Gary, and Gary still plays the trombone in, I think it’s the, he’s in like a community band and he’s also like in a St. Olaf,
Tessa Murry (10:19.082)
Huh.
Reuben Saltzman (10:26.456)
Fascinating. That’s some good background on that, yes.
Tessa Murry (10:26.802)
I didn’t know that. I didn’t know that little nugget. That’s fun. Yeah.
Steve (10:39.425)
alumni band as well.
Tessa Murry (10:41.58)
Well, and you guys have carried on the tradition of music, right? You guys have a stage in your new building located in Oakdale, Minnesota, and you have a lot of people on your team that play, right?
Steve (10:46.232)
Yeah.
Steve (10:53.121)
Yeah, yeah, quite a few. I’m not one of them, but my business partner Bill has been in a band, a Twin Cities band since he was in college in the 90s. When I first met Bill 25, 30 years ago, he would take two weeks off of work and they would tour on the East Coast with his band. And Colin has been the bass player in the building science band for, you know, a couple of decades. And so, yeah, when, people get together, they’re like, yeah, let’s, let’s stay late and
Let’s get up on the stage and we’ll make some music too.
Tessa Murry (11:24.364)
Oh my goodness, that’s so fun. So, okay, so before we dive into, I want to ask you some more questions about Bloor Doors specifically, because I mean, we have an engineer here who like designs these systems. So why shouldn’t we? But before we do that, I’m just kind of curious. You guys started with Bloor Doors, but what have you seen change in the industry in the last like five or 10 years since you’ve been working at TEC and kind of what holes are you guys trying to fill now?
Steve (11:34.969)
You
Steve (11:49.561)
So the biggest change since I started has been generation two of the TrueFlow grid. So Tessa, you’re familiar with this, but Ruben’s probably not. And I’ll introduce this by saying I’ve been doing flow measurement for, like I said, 25, 30 years. And I’ve run into some really difficult things to measure flow of, but it turns out that probably two of the top five hardest things that I know of in all my years of flow measurement.
Reuben Saltzman (11:58.82)
No.
Steve (12:19.255)
are in your house. And the first one is how much airflow is going through your furnace. Turns out that’s really hard to measure. Then the other thing is how much airflow comes out of each supply register in your house. And those are difficult to measure for different reasons. But, know, TEC has tackled both of those. We used to have a flow hood, which is what you put over the supply grill to measure air out of each one.
We’re working on a new generation of that. within the last five years, we released generation two of the TruFlow grid. And the TruFlow grid is a device that you put in place of the furnace filter, and it measures how much air is going through the furnace. And at the same time, it takes pressure measurements in the duct work on the supply and the return duct side of the furnace so that we can measure both the airflow and the static pressure.
Reuben Saltzman (12:49.464)
Yep.
Steve (13:17.665)
And static pressure is important because it’s kind of like blood pressure. If it’s too high, you got a problem. There’s no such thing as blood pressure being really too low, but pressure in your furnace matters.
Reuben Saltzman (13:31.924)
Okay, all right. Now, this just vaguely rang a bell when you mentioned it. Tessa, we saw the True Flow grid when they were back on Hiawatha at their old location, didn’t we?
Tessa Murry (13:43.588)
Yes, I believe so. And did we also have, I feel like we also had maybe Jake show some of our home inspectors how to do that measurement at one point in time as well. So Jake from the Energy Conservatory came out and set up that test for us and tested a furnace, think at one of your properties, Rubin-Meer rental properties.
Reuben Saltzman (13:45.942)
Yeah, we saw someone demonstrate it.
Reuben Saltzman (13:56.482)
Yeah, yeah.
Reuben Saltzman (14:07.808)
It wasn’t mine, but I remember seeing a demonstration of it. And I thought it was at their shop, but maybe I’m confusing it with something else.
Tessa Murry (14:09.708)
okay.
Tessa Murry (14:13.44)
Yeah. Great. Maybe it was that. Maybe I’m mixing up my time at the U of Sorry. But anyways, yes, you’re right, Ruben.
Steve (14:22.489)
But yeah, the the true flow grid and particularly the app. So we had an original version of the truth flow grid, but it was a little more of a science project. It didn’t guide the technician through how to make the measurements and then how to interpret the measurements. The original one, you know, we sold a few, but not a ton. This latest one, because it has an app to guide people through it and to help them understand what should I do with these results? It’s really, you know, broken open.
how useful it can be for an HVAC technician to actually know how many cubic feet per minute of air is going through the furnace or through the air conditioner. Because it turns out, if you read the energy guide label on your furnace, you see that it’s a 96 % AFUE and that your air conditioner is a 16 seater. In order to get either of those advertised efficiency numbers, the airflow has to be correct.
Reuben Saltzman (15:22.168)
Sure.
Steve (15:22.457)
And it’s really difficult for the technician, even if they do a great install, if they don’t have a good way to measure that, they can be completely off and the airflow can be incorrect. And that means for the life of the system, it’s not getting the efficiency. It might not be producing the capacity that’s supposed to. And airflow, either high or low, can make the furnace or the air conditioner fail prematurely.
Reuben Saltzman (15:50.242)
Yes. Yes.
Tessa Murry (15:51.668)
These are also important. It’s it’s fascinating to me that like this is something that’s not done when they install these systems that cost 10, $20,000. Like nobody’s checking them in the industry unless you’ve got a company, it seems like that’s had lots of callbacks or complaints and then they’re trying to figure out what’s going on and how to fix it.
And then they, you know, then they realize, okay, well, we need to do some more testing to dive into this because there’s these, you know, there’s equipment that fails five, you know, or a few years after you install it, it shouldn’t be failing that early. Why is that? Okay, well, the pressures are off, you know, or the airflow is off or people having comfort issues when they just put in a brand new system and they can’t figure out, you know, why it’s not distributing air the way that it should. And all these things can be measured and can be calculated and can be fixed. But it’s like
Nobody’s doing it, it seems like.
Steve (16:40.833)
Yeah. Yeah.
Reuben Saltzman (16:43.022)
Who? Let me ask you, who is doing this? Is anybody doing? Obviously people are doing this. You got a product, you’re selling it. Are there people here in the twin cities who are doing this?
Steve (16:53.561)
A There are a few HVAC technicians that have a true flow in the Twin Cities and are measuring the airflow when they install a new system. Not very many.
Reuben Saltzman (16:55.721)
Okay.
Reuben Saltzman (17:03.608)
What? Okay, you say technicians. When you say that I’m thinking of individual people. Are you talking about like their shops who do it? Like larger companies or
Steve (17:06.541)
Yep, HVAC technicians.
Steve (17:13.387)
No, well, so there’s a couple different people that might show up at somebody’s house to measure airflow. One is an HVAC technician, so know, furnace company. Another one is an energy rater. So when you build a new house in order to meet the energy code, you have to meet all the other building code stuff, but typically there’s also a third party energy rater that has to verify that.
Reuben Saltzman (17:21.656)
Okay. Okay.
Tessa Murry (17:30.251)
you
Steve (17:41.165)
the house meets the air tightness requirements, that it meets the insulation requirements, that the windows meet the code and all that stuff. And the energy reader will also sometimes measure airflow through the new HVAC system in a new house. And that’s done because in states that are using the HERS system for energy code points, you get extra points if they can verify that the airflow is correct.
and that the Watt draw is correct on the HVAC system.
Reuben Saltzman (18:13.11)
Okay, got it. And so are you comfortable naming any shops here in the Twin Cities who are doing that? Or do you even know maybe you don’t? Okay.
Tessa Murry (18:13.782)
Hmm. Hmm.
Steve (18:21.849)
There aren’t any big ones. There’s a couple small ones. And most of them get connected with the Truflow grid. They’re attending. So the Center for Energy and Environment in Minneapolis does a lot of training of HVAC technicians. And if you take their training, they’ve got a new heat pump training program that they’re putting together. And a lot of them that are getting Truflow grids
are attending that training, they’re learning about heat pumps, because it turns out that the target that you have to hit for airflow on a furnace is the broadside of a barn. The target’s much wider for a furnace than it is for a heat pump. And so as people move people from furnaces to heat pumps because there’s incentives, because there’s green energy programs and incentives to do that.
Tessa Murry (19:02.636)
Thank
Steve (19:19.417)
airflow becomes more important and you have to move more airflow to deliver the same heat with a heat pump as you do with a furnace. so that’s people involved with that training and heat pumps are more likely to have a true flow grid to know how to commission a system.
Reuben Saltzman (19:21.582)
Mmm.
Reuben Saltzman (19:30.359)
Okay.
Reuben Saltzman (19:40.407)
Okay, now Tessa, I’m going to take us really in the weeds here, bring it down from like way up here, right down to earth for us lowly home inspectors. Got to ask you a question here, Steve, and maybe you don’t have any good way of answering this, but you know, as home inspectors, we’re not doing any type of this diagnostic stuff. I mean, I don’t know what we’d do with it, even if we did figure it out, because
Tessa Murry (19:45.836)
Please do.
Steve (20:03.947)
actually one of your home inspectors did a good job of it on a house that I on a house I was considering. Yeah.
Reuben Saltzman (20:07.83)
Okay, all right. Well that that’s what I’m getting to. I just want to tell you what we do and I’d love for any feedback that you could share for I mean both for me and for any of the other home inspectors listening. We’ve talked about our podcast in the past. I mean we do a very basic test. We check the temperature rise on the furnace. You fire the furnace up and check the air coming in the air going out and does it fall within the manufacturer’s spec? That’s what we’re doing.
Tessa Murry (20:27.648)
Mm-hmm.
Tessa Murry (20:34.079)
Mm-hmm.
Reuben Saltzman (20:36.854)
Is there something better, quick and dirty that we could do? What kind of advice would you have for us?
Steve (20:41.817)
Yeah, so there’s. Yeah, so I would say that that one and then so the other test that was done. So the temperature rise. Let’s say a common temperature rise is 30 to 60 degrees. So that means that if the air is coming in at 70 degrees, then it is going out at between 100 and 130 degrees. So it’s the temperature rising by between 30 and 60 degrees.
Reuben Saltzman (21:01.112)
Mm-hmm.
Steve (21:10.519)
If your temperature rise is near the maximum, that means your airflow is near the minimum. And that if the airflow is near the minimum or sometimes below the minimum, then it can trip what’s called the high limit switch. So I’ll give kind of a zoom out of a furnace. A furnace has, you know, the fire inside the furnace is contained within the
Reuben Saltzman (21:19.288)
Tracking. Yep. Yep.
Steve (21:40.227)
combustion side of the heat exchanger. And typically that starts with, you know, stainless steel or alloy tubes. And then it goes into another heat exchanger and the fires on the inside and the air from your house is circulating on the outside. So the heat goes from those hot fire tubes into the air from your house. And it turns out that because you’re, burning a fixed amount of gas on the inside, you’re going to be putting a certain amount of heat into that air.
Reuben Saltzman (22:00.461)
Mm-hmm.
Steve (22:10.185)
And if the air is moving more slowly because there’s not as many cubic feet of air going through the furnace, it’s going to get hotter. So if we dump the same amount of heat into less air, the air gets hotter. If we dump that same amount of heat into more air, the air doesn’t heat up as much. So that, you know, the temperature rise and the airflow are inversely related.
higher temperature rise, lower airflow, and vice versa. And so I mentioned that there’s a high limit switch. So inside the heat exchanger, there’s a temperature sensor, and it is measuring the temperature of the heat exchanger while the furnace is running, and it has a maximum limit. So if the manufacturer says that temperature rise should be between 30 and 60 degrees,
there might be a limit switch that’s actually going to shut it down if it gets much over 60. So maybe if it gets up to 70 degrees of a temperature rise, it will actually turn off the gas. one of your technicians who did a home inspection, he noticed that when he turned up the thermostat, so it was like 65 degrees in the house, it was unoccupied and he turned up to 85 degrees. And when you do that, it should keep running.
Tessa Murry (23:18.912)
Mm-hmm.
Steve (23:37.273)
until it satisfies the thermostat at 85 degrees. He noticed that the furnace turned off way before it got to 85 degrees. And what happened is it had triggered the high limit switch. So the furnace gets hotter and hotter and hotter. And eventually it will get to a stable temperature, right, where it won’t get any hotter. And but if there’s not enough airflow,
Reuben Saltzman (23:40.471)
Right.
Tessa Murry (23:40.768)
Mm-hmm.
Tessa Murry (23:48.383)
Mm.
Reuben Saltzman (23:59.854)
Mm-hmm.
Tessa Murry (24:00.051)
Mm-hmm.
Steve (24:07.243)
it will get too hot before it ever gets to that stable temperature. And that will trigger it to turn off. so what happens is the, you know, and what happens is it will turn off the gas to the furnace. The furnace will still be running the blower and it’ll still be, you know, your thermostat will still say it’s calling for heat, but it’s turned off the gas temporarily because the heat exchanger got too hot. I might,
Reuben Saltzman (24:11.808)
Sure.
Tessa Murry (24:12.907)
Mm-hmm.
Reuben Saltzman (24:23.362)
help.
Reuben Saltzman (24:33.496)
Sure.
Steve (24:35.705)
second house that I lived in for 20 years. The whole time I owned that first furnace, it was cycling on high limit. If it ever ran more than about four or five minutes, the high limit switch would shut off the gas. And then when it cooled down, it would let the gas go back on. And then three or four minutes later, it would turn it off again, off again, on again. So that’s, it’s called cycling on high limit. Sometimes it’s called short cycling, which is a little bit of a different thing.
Then cycling on the high limit. High limit means that it’s actually the high temperature limit switch is turning off the gas.
Reuben Saltzman (25:09.312)
Okay, what’s short cycling? Because I’ve used the two terms interchangeably.
Steve (25:13.421)
So short cycling is normally a symptom of just having a furnace that’s too large for the house. And that means that it can, because it’s way bigger than the house needs, even if it has adequate airflow, you can turn it up five degrees and it will, well, normally short cycling just means cycles are too short. You don’t want the furnace to go on for a minute.
Tessa Murry (25:13.646)
Yes.
Steve (25:43.001)
and then be off for 15 minutes.
Reuben Saltzman (25:45.728)
So you’re defining short cycling as a furnace that satisfies the thermostat much faster than we would expect it to. Isn’t that right? Okay.
Steve (25:55.351)
Yes. Yep. And that can be, that can be a couple things. It can be just because the furnace is way bigger than the house needs. It can also be because the thermostat has the difference between the turn on the temperature, turn on the furnace temperature and the turn off the furnace temperature are really close together. this is a setting kind of deep in the thermostat settings. Sometimes they call it the swing or the temperature.
Tessa Murry (25:56.544)
Okay. Okay.
Reuben Saltzman (26:17.378)
Mmm.
Steve (26:23.993)
difference or the temperature delta. But it’s basically, you know, if you set up for 70, that means it’s going to go on when it gets down to maybe 69 and it’ll keep warming up until it gets up to 70 and then it’ll turn it off. So that would be a one degree temperature delta, but I’ve bought thermostats where the temperature delta was a quarter of a degree, which is crazy small. Yeah. Which means it’s just cycling like mad.
Tessa Murry (26:25.932)
Thank
Reuben Saltzman (26:48.462)
Crazy.
Tessa Murry (26:50.186)
Yeah.
Steve (26:51.957)
it, it goes on, it satisfies a quarter degree. turns off and on, like you don’t want it to be a quarter of a degree.
Reuben Saltzman (26:56.5)
It seems like it would go on it would turn off if you stand too close to it. That’s good
Steve (27:00.855)
Yep, yep, exactly. Yeah. And so, and then another well-known brand that I happen to like a lot, theirs is half a degree and I always switch it to a degree. It’s better, you know, a degree or a degree and a half if you don’t notice the difference, you know, because longer cycles are better for any furnace, any air conditioner. You want long cycles. Yeah.
Tessa Murry (27:01.662)
I’m
Reuben Saltzman (27:15.36)
Okay. Okay. Yeah.
Reuben Saltzman (27:21.966)
Okay, and now you’re making me think I should adjust my thermostats and I should change this cycle. Can you do it for most thermostats if you know how to get here?
Steve (27:31.735)
Yeah, you just have to look for it. It can be called the dead band. It can be called the swing. It can be called the temperature delta. But yeah.
Reuben Saltzman (27:38.732)
Okay.
Okay, I told you I’m getting in the weeds here. I’m not done. No, I’m just kidding. Yeah, no, this is what I like to talk about.
Tessa Murry (27:41.952)
you have a programmable thermostat. I’m loving this. Well, one thing I want to circle back to see, okay, now you mentioned this high limit kind of short cycling that can happen where the unit gets too hot, the furnace gets too hot and it shuts off prematurely. And a lot of times that’s related to airflow potentially and maybe it’s got restricted airflow and that’s causing it to get too hot and to cycle off. So I was always taught
Steve (27:44.823)
Yeah. Yeah.
Tessa Murry (28:10.668)
The furnace filters play big part in that potential airflow restriction. Now, talking to you recently at an HVAC conference, I learned something new. So Steve, I thought that a one-inch paper pleated filter was kind of the way to go. And the higher the MIR rating, the thicker the filter, the more restrictive that got, especially when it got dirty.
Can you explain to me why that’s wrong and what we should actually know about furnace filters?
Steve (28:44.119)
Okay, the only thing that you really need to be worried about with your furnace filter is what’s the pressure drop across it. Unfortunately, most of us don’t have a micromanometer in our house and we can’t measure that. And so there’s several things that make a filter restrict airflow more. The first one is that whoever designed the system just used too small of a filter.
Reuben Saltzman (28:57.055)
Mmm.
Steve (29:13.101)
for the size of furnace and air conditioner that you have. The second one is they’ve used, somebody’s put in a furnace that just, or sorry, a filter that’s just too restrictive. Generally speaking, the higher the MIRV rating, the more restrictive it’s gonna be. But there’s exceptions to that. And I did have a little, you know,
Tessa Murry (29:16.908)
you
Steve (29:41.593)
COVID lockdown project where I went to this store and I bought a whole bunch of furnace filters. And because we can measure pressure drop in airflow with our equipment, I set up a little laboratory with a cardboard box in my basement and I measured a whole bunch of filters. And I found out that one particular brand was just like you’d expect. Their MERV 13 filter restricts airflow way more than their MERV 8 filter. Okay. Another brand.
Reuben Saltzman (29:53.356)
Yes. Yes, I love it. Go on.
Tessa Murry (29:55.958)
What’d you find?
Tessa Murry (30:08.364)
Okay.
Reuben Saltzman (30:09.292)
Yeah, you’re talking about 3M. Come on. Nobody listens anyway. You can be an ass. OK. All right. OK. All right.
Steve (30:11.777)
No, that, no, no, that, so that was, that was not 3M. You’ll love this if you love, you know, the hometown team 3M here, because when I measured the 3M filters there, I measured a Merv 7, 8, 11 and 13 3M filtrate filter and the pressure drop on all of them was about the same.
Reuben Saltzman (30:21.463)
Okay.
Reuben Saltzman (30:39.278)
fascinating.
Steve (30:40.279)
So I believe that 3M is adding more pleats as the filter media restricts the airflow because if you add more pleats, you get more area. And if you have more area, it restricts the airflow less. So more pleats is good, but so is deeper pleats. So if you get the four inch deep filter, it’s way less restrictive than the one inch deep filter.
Reuben Saltzman (30:56.856)
Sure. Yes. Okay. Yep.
Reuben Saltzman (31:08.856)
Sure. Sure. Makes sense. Yep.
Steve (31:10.041)
Because if you actually take that filter out of the box and you stretch out the accordion, you’ll find out that the one in the four inch deep filter is three times as much filter fabric as the one inch deep filter because the pleats are way deeper. so, yeah, you’re going to have air flow can be restricted by the filter because the filter is too small, because it’s not a deep filter.
Reuben Saltzman (31:27.596)
Yeah. Yeah.
Steve (31:40.723)
or because you bought one of the brands where the Super Duper Merv 14 is just a super restrictive filter and they didn’t put more pleats in. And so it’s just restricting airflow. Unfortunately, it’s hard to know if you have that problem without measuring both static pressure and airflow.
Tessa Murry (31:51.82)
Mm.
Reuben Saltzman (31:55.011)
So.
Reuben Saltzman (32:01.615)
You didn’t like publish the results of this, did you?
Steve (32:05.177)
I’ve shared them. Yeah, and well, and the sample is really small. found like there’s like two brands and like five filters, four or five filters of each brand and a couple of other ones that were deep because I didn’t have deep filters of those two brands.
Reuben Saltzman (32:09.816)
Okay.
Reuben Saltzman (32:23.566)
Okay, all right, so thumbs up. Well, yeah, I mean, come on, this is fascinating. So you’re saying thumbs up to the 3M filters at whatever MIRV rating they have, it’s gonna be fine.
Tessa Murry (32:24.512)
Ruben, are you thinking guest blog?
Yeah.
Steve (32:38.359)
Yeah. So yeah, the other thing is that the 3M filtrate filters, they have a little table right on the side of the filter. And it says how many CFM of airflow and how many inches of water the pressure drop will be. And the measurements that I made were very close to what they publish right on the filter.
Reuben Saltzman (32:56.653)
Mmm.
Reuben Saltzman (33:02.222)
Sure. Sure.
Tessa Murry (33:02.324)
Wow. Okay.
Steve (33:03.881)
And generally, when you’re designing a system, you don’t want that to be more than about 0.2 inches of water. so if you’re looking at one of those 3M filters, you sort of have to know how many CFM your system needs. But if you’ve got a four ton air conditioner, a big one, and you’ve got a 16 by 20 filter, one of the smaller ones, what you would see is that
If you run the airflow required for a four ton air conditioner through a 16 by 20 filter, the pressure drop is going to be like 0.5 and you’re supposed to be under 0.2. So that’s like two and a half times more pressure drop than you should have. So you have to kind of learn a little bit about it. You have to do some math. But generally the airflow for air conditioning in our area is for each ton of air conditioning, you should have about 400 cubic feet per minute of airflow.
Reuben Saltzman (33:43.458)
Mmm.
Reuben Saltzman (33:46.957)
Yeah.
Steve (34:03.447)
So a two-ton air conditioner needs about 800 cubic feet per minute. A three-ton needs about 1,200 cubic feet per minute.
Reuben Saltzman (34:11.886)
Okay, okay. And so how would we convert these hundreds of feet per minute to filter size? And basically what I’m looking for here is just some kind of general rule where you say, look, if you’ve got a four ton, I would expect to see a filter size minimum of 16 by 25 by one.
or I shouldn’t say by one, 16 by 25, something like that. I mean, is there some kind of general rule you could use for both college and for BTUs for the furnace?
Steve (34:40.334)
Yeah.
Tessa Murry (34:41.44)
Mm-hmm.
Steve (34:45.707)
Yeah.
There’s not a rule of thumb for like, like how many BTUs does your furnace need to be for the size of your home, mean? so, right.
Reuben Saltzman (34:55.24)
No, no, mean for the size of the filter. Like if I saw a 16 by 20 filter on a hundred thousand BTU furnace, can I just kind of glance at it and go, we’ve probably got a problem here? Okay.
Steve (35:02.989)
That’s a problem.
Yes, that’s a problem for sure. ACA, which is the Air Conditioning Contractors of America, is an industry trade group that also provides standards for how to design ductwork and filters and how to size furnaces and air conditioners. And they recommend 300 feet per minute face velocity or lower. Still going to have to do some math to get from.
Tessa Murry (35:09.014)
Hmm.
Steve (35:35.865)
to get from cubic feet per minute to face velocity for the filter. But that’s a rule of thumb that can be used. I could make a table that we could share. generally, if you’ve got 100,000 BTU furnace, should have a 20 by 25, maybe even bigger. 20 by 25 by four would be better than a 20 by 25 by one.
Reuben Saltzman (35:49.73)
You can email it to me, please. And thank you.
Tessa Murry (35:51.82)
Thanks.
Tessa Murry (36:04.47)
which we see never.
Steve (36:06.233)
And also, so my house has 100,000 BTU furnace in it, and it really needs a 40,000 BTU furnace.
Tessa Murry (36:16.62)
Steve (36:18.007)
That’s how big, that’s how much we’re oversized. Oversizing furnaces is a major problem. It’s a major cause. So what happens is the furnace gets oversized and now the duct work isn’t really big enough for the airflow that that big furnace needs. But the house doesn’t need that much heat. And so if you downsize the furnace to what’s really needed,
Reuben Saltzman (36:20.973)
my goodness.
Tessa Murry (36:21.366)
Wow.
Steve (36:47.065)
Now the airflow is just fine. And also, guess what? You won’t be able to hear it when it goes on because a properly sized furnace with properly sized air ducts is super quiet. When you’re trying to run 100,000 BTU furnace in a duct system and a house that only needs a 60,000 BTU furnace, you get way more airflow. And your furnace is trying to cram the airflow through it so that it can not trigger the high limit.
Tessa Murry (36:50.123)
Yeah.
Tessa Murry (36:55.147)
Yeah.
Reuben Saltzman (37:01.197)
Yes.
Tessa Murry (37:01.803)
Yeah.
Steve (37:16.625)
and I just can’t move it and that makes it loud.
Tessa Murry (37:21.174)
Gosh, you know, I’m just thinking, Steve, like there are so many homes out there that have issues with comfort and efficiency and condensation and air quality. I’m just thinking all these things go hand in hand. It’s like, do you want to make sure that your furnace or AC is the right size for your building? Right. And you also make sure the duct work then is the right size to distribute the right amount of air and heat and cool. But then like that depends on
How is the building envelope? Is it really leaky or not so leaky? And it’s like, okay, so where do you start when you’re looking at making a house higher performance? What type of tests would you say are the most beneficial and important to do when you’re trying to evaluate where is this house at and how can we make it better and have the biggest impact?
Steve (38:09.505)
I wouldn’t start with the heating and cooling unless there’s a real specific problem. I would start with the blower door test in Minnesota. Well, and actually most places I’d start with the blower door test. If I’m in the South where duct work is in a crawl space or attic, I might start with measuring duct leakage instead of building leakage. But in the North, where most of our ducts are inside of the envelope, I would start with the blower door test.
Reuben Saltzman (38:36.108)
No.
Reuben Saltzman (38:39.502)
And the, oh, go on. Sorry. Maybe I just stepped on what you were going to say. Well, I think you’re going to say it. I mean, I was going to ask you, you know, why the blower door? The idea is you get the blower door dust and then you find out your home leaks this much. And then the next step is to hire an energy professional to come in and track down where all these leaks are and fix them. Is that right? Okay.
Steve (38:39.671)
And the reason for that. Go ahead.
No, go ahead if you got a question and I’ll direct my answer.
Steve (39:03.491)
Yep, right, yep. And the reason I would start there is because there’s just so many different problems that come from a leaky building envelope. Moisture problems are very often related to a leaky house. Comfort problems are usually related to a leaky house. The high energy bills are often related to a leaky house. So if you can keep…
Tessa Murry (39:27.53)
Mm-hmm.
Steve (39:30.425)
the hot air in in the winter and the cool air in in the summer, then everything just goes better. And, you know, the problem is that, you know, hot or cold air is carrying moisture with it. And so, you you guys have probably been up in attics in the wintertime and you see frost on the roof deck. Well, yeah, once or yeah, once or 12000 times. Where does where does the moisture come from?
Tessa Murry (39:34.376)
Mm-hmm. Mm-hmm.
Tessa Murry (39:50.304)
Mm-hmm.
Reuben Saltzman (39:50.4)
once or twice.
Yeah.
Reuben Saltzman (39:58.994)
I’m saying the house.
Steve (40:00.429)
Yep. Yeah. And it comes from the house. How does it get from the house into the attic?
Tessa Murry (40:01.483)
Yeah.
Reuben Saltzman (40:05.216)
Attic Air Leaks, Attic Bypasses.
Steve (40:06.923)
Yeah, exactly. All the holes in the ceiling are letting the warm, humid air. You know, got a humidifier in your house to keep it comfortable in the wintertime. And then that humid air leaks through all the leaks. And then, you know, the roof deck, especially at night, is super cold. And so that humid air is just going to condense on, you know, the nails poking through or right on the surface of the OSB or the plywood.
Tessa Murry (40:15.702)
Mm-hmm.
Steve (40:32.921)
And it stays there until the sun comes up or it gets above freezing and then it melts and maybe it drips into the insulation. And that causes moisture in attics, which isn’t good. But that same thing, you’re losing that expensive warm air that you paid to heat and you paid to humidify. And every time there’s a cubic foot of air that goes through the ceiling,
Tessa Murry (40:40.982)
Hmm.
Reuben Saltzman (40:53.538)
Yes. Yes.
Tessa Murry (40:53.74)
Thank
Steve (41:01.729)
There’s another cubic foot of cold air that’s coming in down the basement and making the basement colder and drier in the wintertime and the opposite in the summertime.
Tessa Murry (41:10.518)
Mm-hmm. Mm-hmm.
Reuben Saltzman (41:11.63)
Sure. Yeah. Yeah.
Tessa Murry (41:15.03)
Yeah. So starting with the building envelope is what you would recommend. And you need a blordor test to do that. And a lot of times if you’re working with a contractor who is trying to figure out where these air leaks are, if they’ve done it for a long time, a lot of times they’re familiar with where to look for these common leaks. But you can use an infrared camera or smoke to try and track these things down and actually air seal them and stop them.
So blor door, that’s why it’s so important to do that testing, not only just to make sure the house meets the current code requirements, but for all these performance factors you’re just talking about. And then once you get the building envelope right, then I mean, that can impact sizing of the equipment, right? And what size system you should put in your house for the best comfort and efficiency, right?
Steve (41:59.917)
Yep. Yeah, exactly.
Reuben Saltzman (42:01.902)
Yes. And you know, I want to touch on something that it’s like, we almost just kind of glossed by you talked about the fact that you’ve got a 100,000 BTU furnace in your house, but your house really needs about a 40,000 BTU. But the point we almost went over is the fact that you still have it. And yeah,
Steve (42:21.945)
So I fixed it in my previous one. We recently moved a couple of years ago. it’s, yeah. Yep.
Tessa Murry (42:22.984)
Why? Yeah, why?
Reuben Saltzman (42:29.035)
Yeah, so you’ve been living with it for a couple of years. I mean, at what point is it just cost prohibitive to even mess with it where you just say, look, this is what I got. And this is what I’m going to have until my furnace cocks out and I’m going to deal with the consequences of
Steve (42:41.613)
Well, the, fortunately mine is a two stage furnace. And so I talked to an HVAC technician friend and he taught me how to lock it into low stage. So low stage is about 65,000 BTUs, which is much more reasonable. but I found out when I tried to run it in high stage that it won’t even run in high stage. It will hit the high limit in about two minutes if it tries to run on high stage. Yeah. So it wouldn’t even run.
Reuben Saltzman (42:47.639)
Okay.
Steve (43:09.113)
high stage at all. So he showed me, know, here’s what you, here’s the setting on the dip switches. So you can lock it into low stage. it’s now it’s running as a 65,000 BTU furnace. Um, and it’s just working fine. It’s a newer furnace. You know, that’s a, that’s a solution to that problem. If you have a two stage furnace, you know, figure out how to lock it into, um, into low stage. And, um, you know, that, that improves that, you know, my previous house, I had an 80,000 BTU furnace that was cycling on high limit and I didn’t even know what
Reuben Saltzman (43:22.678)
Okay. Okay.
Steve (43:38.553)
high limit was, or that it was cycling until I started at the energy conservatory and learned about stuff. And in that house, I added on about 30 % to the square footage. And then I went from an 80,000 BTU furnace down to a 60,000 BTU furnace, which was properly sized. Yeah. So according to the load calculation, I added 30 % to my square footage and the heat required to heat my home went up 5%. And the.
Tessa Murry (43:55.884)
wow.
Tessa Murry (44:06.964)
Wow.
Steve (44:09.258)
Air conditioning required to cool the home actually went down by adding on because the addition was so much more efficient than the part of the house that got covered up by the addition.
Tessa Murry (44:14.156)
Mm.
Reuben Saltzman (44:22.478)
sure, sure, okay.
Tessa Murry (44:23.006)
Huh.
Steve (44:24.609)
So if you, you you got three walls of the addition covering up one wall and the amount of heat getting lost through those three walls in the attic was less than what it covered up.
Tessa Murry (44:30.87)
Mm-hmm.
Reuben Saltzman (44:36.77)
Fascinating.
Tessa Murry (44:36.936)
Wow, impressive. was gonna say, you know, and then this, all of this HVAC stuff that a house, you know, the factors into performance and efficiency and comfort, you know, you would hope when you hire an HVAC contractor, they are aware of these things and these variables and these tests, and that they’re doing these things when they install a system or duct work. But from our experience, from my experience, I’d say
Most of them don’t. They shriven shaking his head. No. And so what was very interesting to me is going to this HVAC conference with you guys in Orlando in January was the amount of contractors from around the country that came to get education on kind of, you know, what they can be doing to do a better job in the industry.
And you guys, the TEC, are one of the core, I feel like, educators in this area that say, okay, here are the tests that you can do and should be doing, and here’s what it measures, and here’s why it’s important. And you provide the equipment in these apps that make it super easy for a technician to just plug in this data into an app that literally then tells them, put in this size furnace, adjust it to this airflow with this filter.
and hear the parameters for what you need. And they can install a system that is going to guarantee work the way that it should and deliver the performance that it should. And especially these contractors that are doing retrofit work. We’re talking about how the house is changing, they’re changing out systems, or they’re maybe going from a standard furnace to a heat pump. You really need to know these things to get it right the first time.
you’ve seen companies, large companies, not do these measurements, just kind of throw in the same system that was there in the past because that’s what they’re putting in now. It worked before, why not do it again? And then they get all these callbacks and they realize, okay, the way we can fix this and reduce our callbacks and make more profits and have happier clients is if we actually do these 10 minute tests with this equipment every time to make sure we get it right. And so that to me was just pretty mind blowing and also inspiring that there are contractors out there.
Tessa Murry (47:00.752)
that are learning this stuff and know this stuff, but it’s just like every, I feel like like every industry in building, it’s just a dinosaur. It’s moving so slowly.
Steve (47:12.813)
Yeah, yeah, to reinforce that, you know, when Gary started the company in the early 80s, he thought to himself, and he shared this a lot of times, he’s like, I figured in probably five or maybe 10 years, every general contractor will have a blower door. Because they’ll want one, they’ll need one. Right. Why wouldn’t they? Well, here we are, you know, 40 years later and
Reuben Saltzman (47:12.846)
.
Tessa Murry (47:30.112)
right? Why wouldn’t they? Yeah.
Steve (47:38.521)
There are a few general contractors that have a blower door now But mostly who has blower doors is this whole other industry that has been created called energy raiders And it’s their job to make sure that the general contractor is meeting the energy code And so that’s you know, it’s it’s been it’s been strange
Reuben Saltzman (47:57.817)
Yeah.
Tessa Murry (47:58.281)
Yeah, man. Well, I feel like we could keep going. We could keep diving into this more, Stephen, and get into the weeds as far as show us some more Blurred Or stuff. But, you know, we’re hitting time here, so we should probably wrap this up.
Reuben Saltzman (48:04.846)
.
Reuben Saltzman (48:10.35)
We don’t have time to get into another topic because it’s going to be 20 minutes. We just we can’t but I would love to.
Steve (48:14.297)
Yeah. In about, yeah, in about two minutes, I can share that there are a couple of things that homeowners and inspectors can think about in styles of homes that are leakier. It turns out that a plain rectangular house is usually more airtight than one that’s more complicated. If you got all sorts of dormers and stuff like that.
Tessa Murry (48:16.492)
We’ll have to have you back.
Reuben Saltzman (48:27.758)
Please.
Tessa Murry (48:38.782)
Yes, simpler is better.
Reuben Saltzman (48:42.092)
Yeah.
Steve (48:42.173)
And, you know, L shaped or T shaped houses, you know, all those places where walls meet are where the leaks happen. Another thing that makes a huge difference is whether you have an older home. Typically before World War Two, they did what’s called balloon framing. And after World War Two, at World War Two, it became platform framing. The balloon framing used less wood. And I think that’s why they did it back in the day. But
Reuben Saltzman (48:49.238)
Okay, yep.
Tessa Murry (48:50.348)
Yeah.
Steve (49:12.235)
It was way leakier. What a balloon framed house means that there are no top plates and bottom plates in the walls. Usually there’s a bottom plate in the basement, but the walls go all the way from the foundation up to the roof rafters and there’s no top plates there. Today they build the lower level and then that’s the first platform and then they put the floor on it and the subfloor goes across and then they put the walls on top of that.
Reuben Saltzman (49:40.579)
Yeah.
Steve (49:42.007)
that requires more wood, it’s easier to do. And a balloon framed house, you could go up into the attic and if there’s no insulation in the walls, which frequently there was no insulation back in those days, you could actually drop a ping pong ball in the wall cavity cavity from the attic and it would drop down into the basement. Just all go all the way. There’s like nothing in there. And those houses are super leaky because there’s no top plates or bottom plates to control the airflow at all.
Reuben Saltzman (50:02.434)
Yeah.
Tessa Murry (50:03.572)
a fun game.
Steve (50:11.609)
And so if you have a pre-war house, it’s likely to be balloon framed. It’s likely to be very leaky. And so that’s something to be aware of, but there’s professionals that know how to seal them up. They seal those wall cavities up from the attic and or from below. They can, they can blow dense packed cellulose insulation into the walls, which helps a lot. So there’s, there’s ways to improve it. Other styles of houses that are a big problem are.
Tessa Murry (50:25.053)
Mm-hmm.
Tessa Murry (50:29.524)
Okay.
Reuben Saltzman (50:35.971)
Yep.
Tessa Murry (50:36.502)
Mm-hmm. Mm-hmm.
Steve (50:42.844)
split or multi-level splits. if you have that you can kind of houses that have you know half of it has two stories the other half has two stories that are under over so there’s there’s four different levels stacked and the problem is the wall where all those stories meet because now you have a floor cavity that goes directly into a wall cavity and that wall cavity goes right up to the next
Reuben Saltzman (50:45.838)
Mmm.
Reuben Saltzman (50:54.157)
Yes.
Tessa Murry (50:54.4)
Mm-hmm. Mm-hmm.
Steve (51:08.985)
floor cavity or to the attic to the side. And so that’s just paths where air can leak. So multi-level splits tend to be quite leaky. know, houses that are more complicated tend to be more leaky. And generally older homes are leakier than newer homes, particularly if there’s been building code requirements in your state. So Minnesota required blower door testing.
Tessa Murry (51:10.353)
Mm-hmm.
Tessa Murry (51:16.64)
Yeah.
Reuben Saltzman (51:19.299)
Yep.
Tessa Murry (51:20.747)
Yeah.
Tessa Murry (51:27.306)
Mm-hmm.
Tessa Murry (51:32.065)
Yeah.
Steve (51:37.165)
to three air changes per hour or less, and that began in 2015 for Minnesota, so 10 years ago. But a lot of builders were building tight homes before that in our area. I think it’s just easier to notice a leaky home when it’s minus 10 outside.
Tessa Murry (51:42.208)
Mm-hmm. Mm-hmm.
Tessa Murry (51:49.066)
Yes.
Reuben Saltzman (51:55.31)
Yes.
Tessa Murry (51:55.341)
Yeah. Well, Steve, thank you so much for those tips and for all of your knowledge and sharing that with us. We should wrap this up. So if anybody has any questions, they want to learn more about TEC, the Energy Conservatory. They want to check out your tools that you guys sell or learn more about trainings that you guys offer. How do they find that information?
Steve (52:18.509)
Yeah, so the website is energyconservatory.com. We’ve got a YouTube channel that has lots of training videos. You can see a house that we did in St. Paul that actually walk through how to do this. You if you have DIY homeowners that follow your podcast, air sealing is not hard to do, but it’s dirty and it’s tedious and you have to know, and you have to know where to find the leaks.
Reuben Saltzman (52:42.659)
Yes.
Tessa Murry (52:42.796)
I’m sorry.
Steve (52:45.945)
And so, you if you look at a couple of our videos, you know, oh, I can see where it is that houses leak in many parts of the country. The power company will have an energy audit that is sponsored, you know, maybe subsidize it might even be free by the power company. And if you call a power company and see if they have that, a lot of times they’ll do a blower door test and they’ll come out with an infrared camera and a blower door and they can help you locate here some.
places where your house is leaky. yeah, energyconservatory.com. Look at our YouTube channel. It has got a lot of videos on it. Look for us in podcasts. Yeah.
Tessa Murry (53:17.484)
Yeah. Okay.
Reuben Saltzman (53:26.296)
Sweet. Well, we will link to those in the show notes. Yeah.
Tessa Murry (53:27.712)
Thank you so much, Yeah. Yeah. Thank you so much, Steve. It’s wonderful having you on, and we’re going to have to have you back again because there’s a lot more I know we could dive into and talk about.
Steve (53:30.136)
Yeah.
Steve (53:36.631)
Yeah. Yeah, it’s great fun. There’s lots to talk about.
Reuben Saltzman (53:39.894)
Yeah. Yeah. We’ll queue up a lot of stuff. And for our listeners, if you got any questions for us, thoughts, questions, show ideas, whatever, we’d love to hear from you. You can reach us. It’s podcast at structure tech.com. Shoot us an email. We read them all and we will catch you next time. Thank you so much.