To watch a video version of this podcast, click here: https://youtu.be/-Tsv9suvZwc
In this episode, Reuben Saltzman and Tessa Murry discuss kitchen hood fans and exhaust ventilation, focusing on CFM, hood design, ductwork, makeup air, and combustion safety. They explore common ventilation problems found during inspections, explain how excessive exhaust can affect homes, and discuss Minnesota’s makeup-air requirements. The episode also introduces AI-powered calculators to help homeowners determine fan and makeup-air requirements, along with practical tips for improving kitchen ventilation and indoor air quality.
For Reuben’s calculator on the Maximum Exhaust Fan Rating Without Makeup Air, go to https://docs.google.com/spreadsheets/d/1VT9XTGvmk7RVMfh4D-_iveF8LyNhYBelOeqSKS6vPds/edit?usp=sharing.
For the Makeup Air Calculator with Opening Sizing and Home Age, go to https://docs.google.com/spreadsheets/d/1b_899bkGIt8WNK8H6KwrErB9_YO80jAYb2zVy5dIEDk/edit?usp=sharing
Here’s the link to Inspector Empire Builder:
https://www.iebcoaching.com/events
Takeaways
Effective kitchen ventilation depends on proper hood design, placement, ductwork, and capture efficiency—not just CFM.
Larger fans can increase energy use and may cause depressurization or backdrafting in homes with combustion appliances.
Common inspection issues include blocked dampers, disconnected ducts, restrictive ductwork, and improperly configured microwave hoods.
Minnesota makeup-air requirements vary based on fan size, home characteristics, and combustion appliances.
AI-powered calculators can help homeowners and inspectors determine appropriate fan, makeup-air, and duct-sizing requirements.
Proper ventilation helps improve indoor air quality, including when using electric cooking appliances.
Homeowners should use exhaust fans while cooking, check exterior dampers, use back burners, and choose properly designed, quieter hoods.
The key takeaway: Good kitchen ventilation is about effective capture and proper system design—not simply installing the largest fan.
Chapters
00:00 Introduction and AI Report Reviewer Update
02:43 Sponsor Spotlight: Inspector Empire Builder and Rapid Gain Training
04:39 Introducing the Kitchen Hood Fan Topic
05:35 Why Kitchen Ventilation Matters for Indoor Air Quality
07:14 CFM vs. Hood Design and Capture Efficiency
08:11 Why Hood Shape and Placement Matter
10:28 Typical Kitchen Hood CFM Ratings
11:40 Oversized Fans and the Energy Penalty
12:15 Makeup Air for High-CFM Exhaust Fans
13:13 How Ductwork Affects Actual CFM
14:42 Duct Restrictions, Exterior Terminals, and Airflow Problems
15:10 Stuck Dampers and Common Inspection Findings
17:20 Microwave Hood Fans and Recirculating Systems
19:17 How Many Homes Have Proper Exterior Kitchen Ventilation?
20:05 Indoor Air Quality, Cooking Pollutants, and Code Requirements
21:03 Gas Cooking, Carbon Monoxide, and Ventilation
22:15 Minnesota Ventilation Requirements
22:58 The Truth About the 300 CFM Makeup-Air Rule
23:28 National Code Requirements for Makeup Air
26:14 Why One-Size-Fits-All Makeup-Air Rules Can Be Problematic
27:39 Backdrafting Risks in Tight Homes
28:59 Reuben’s New AI-Powered Maximum CFM Calculator
30:39 Factors Used in the Minnesota CFM Calculation
32:50 When a 300 CFM Fan Requires a Calculation
33:31 Calculating Makeup-Air Requirements and Duct Size
34:25 AI-Powered Makeup-Air Calculator
35:23 Making Complex Code Calculations Easier
37:03 Minnesota Code Exceptions and Combustion Safety Testing
38:22 Worst-Case Depressurization Testing
39:06 When Makeup Air May Be Avoided
40:31 Practical Kitchen Ventilation Tips
41:13 Using Back Burners and Choosing a Quiet Hood
41:54 Microwave Vents vs. Proper Capture Hoods
44:30 Why Capture Efficiency Matters More Than CFM Alone
45:25 The Difference an Exhaust Fan Makes in an Airtight Home
47:49 Closing Thoughts and Listener Feedback
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 (00:01.153)
Welcome back to the show. Tess, how you doing today?
Tessa Murry (00:04.886)
Hey Reuben. Hanging in there. Hanging in there. 33 weeks pregnant today. So we’re getting close. You know, I I’m doing pretty good. Yeah. The the the biggest complaint I have right now though is it’s very strange. I have numbness and tingling in my arms, in my hands. It’s gotten so bad. It started where it was just at nighttime. I think I mentioned this earlier. Now it’s like all day. It’s all day. And
Reuben (00:12.655)
Feeling healthy.
Reuben (00:29.871)
Yeah, you did. no. great.
Tessa Murry (00:33.782)
It’s affecting my ability to be able to like type, write, pick things up. So anyways, hopefully that goes away. Yeah. Yeah. Yeah. But but everything else is going well. Going well. How about you? How are you doing?
Reuben (00:39.759)
Huh?
Reuben (00:44.205)
Yeah, hopefully so. Geez.
Reuben (00:51.855)
Okay. Yeah. You look healthy. You look like you got that, you know, that third trimester glow. You’re looking good. You look healthy.
Tessa Murry (00:58.282)
well thanks Ruben. I think that’s probably the the lighting in my in my office here. What’s that little aura ring that you you gave me for podcasting a while ago? Yes. There we go. I have a selfie ring illuminating me. So there we go.
Reuben (01:08.535)
Yeah, the the selfie ring.
Reuben (01:13.815)
Okay. Okay. All right. Yeah. Looks great. Looks great. Yeah, I I can’t complain. Life is pretty good. Yep. Nothing nothing crazy new going on. We’re just kind of chugging along. Yeah. I got I’ve I’ve had meetings with every inspector on the team talking about the new AI report reviewer, and I’m just delighted to say it has been unanimous.
Tessa Murry (01:22.43)
Good. Good. Good.
Tessa Murry (01:29.378)
That’s good. Okay.
Tessa Murry (01:37.144)
Reuben (01:40.865)
adoption and love for it. Like everybody is thoroughly impressed. Yep. So that’s good.
Tessa Murry (01:43.642)
Really? that’s awesome. Well, you know, hopefully it’s I was gonna say hopefully it’s technology that makes their job easier or gives them peace of mind that they’re not missing something, I guess, that could be a future liability. I don’t know.
Reuben (01:59.437)
And and it yeah, and it helps them d to give out a better product that everybody feels good about. Cause I mean it’s it’s a very insightful reviewer. It’s not simply a spell checker. So
Tessa Murry (02:05.677)
Yeah.
Yeah. Yeah.
Tessa Murry (02:13.941)
And it’s fast too. It’s real fast.
Reuben (02:16.558)
Pretty fast. Yeah, you know, five five to eight minutes. Yeah. As long as you’re not sitting there staring at the wheel turn, as long as you can walk away for a second and come back, it’s really fast. If you’re sitting there watching it, it’s a little bit like paint dry. But yeah, it’s pretty quick. Yeah. But
Tessa Murry (02:18.293)
Yeah. Not bad. Not bad.
Tessa Murry (02:27.853)
Right. Right. Well that’s that’s good news. That’s good news because I know not all changes are easily adopted. So
Reuben (02:38.892)
Yeah, yeah. But this one, this one seems to be turning out really well. Yeah, I’m excited about it. before we get too far in here, we should give a shout out to our show sponsors, i.e. B, Inspector Empire Builder. last week we talked about inspection fuel coming up in Louisville, Kentucky. Yes, I got it right this time.
Tessa Murry (02:44.973)
Good. Good.
Tessa Murry (02:53.835)
Mm. Mm-hmm.
Tessa Murry (03:03.053)
Yep. You pronounced that correctly, I think. Hopefully.
Reuben (03:08.93)
Yes, yes. we’re we’re talking about that, but another one that’s gonna be coming up is rapid gain training, also known as RGT. And that one is coming up in the Houston, Texas area. That’ll be October fifteenth through seventeenth. And they they call this their flagship business building program.
For the launch and the builder members. Those are kind of inspectors more getting started in this industry. And you know, they say when someone’s business is growing rapidly, staying flat, or navigating a slower market, RGT is designed to help inspection company owners build a stronger foundation for long-term growth. And owners get to learn how to structure their company for sustainable growth, create marketing systems that
Tessa Murry (03:43.127)
Sure.
Reuben (04:04.76)
consistently generate business, hire, train, and retain the right people, increase profitability instead of simply increasing revenue, and build a business that operates with systems instead of constant owner involvement. And this was your first taste of IEB. This is where you and Eric flew out there right when the world, right before the world melted down for COVID, and you guys weren’t sure if you’re going to be able to get a flight home.
Tessa Murry (04:25.943)
Yeah.
Tessa Murry (04:30.121)
Yes.
my gosh, crazy. It seems so long ago, but yes.
Reuben (04:34.722)
Yeah. But yeah, that’s that’s coming up again the Houston, Texas area, and that’ll be October fifteenth through the seventeenth. So love our sponsors and also just wanted to talk about today’s topic, you know, tying it in. We’re talking about the AI report reviewer. That’s kind of the inspiration for today’s topic. I wanted to talk about Kitchen Hood fans. There’s
Tessa Murry (04:39.785)
I can
Tessa Murry (04:46.527)
A lot going on.
Tessa Murry (04:57.281)
Mm-hmm.
Reuben (05:03.104)
A lot about kitchen hood fans, kitchen exhaust fans, whatever you want to call it, that we haven’t really gotten into on the show. We’ve probably talked about it in fragmented pieces. We’ve probably covered everything we’re going to talk about today. But but I got a new tool to share with people too. So we’ll we’ll get there. We’ll get there. But yeah, you you could probably guess what it is, but we’ll we’ll wait. We’ll we’ll get there later on in the show.
Tessa Murry (05:14.433)
Mm-hmm.
Tessa Murry (05:22.37)
No.
Tessa Murry (05:25.783)
I’m excited. All right.
Reuben (05:32.664)
But first, Kitchen Hood fans. You and I talked for a few minutes before the show, talking about the importance of them. And you were talking about this conference you were at where someone spent a lot of time talking about kitchen hood fans. Can you elaborate on that a little?
Tessa Murry (05:35.351)
Mm-hmm.
Tessa Murry (05:47.274)
Yeah, well, th you know, there’s been a lot of research in the last few years about indoor air quality pollutants and sources and and everything. And it apparently cooking puts a ton of really bad things into the air for us. And it doesn’t matter if it’s natural gas that you’re cooking with or electric s cooktops. They both create
problems for our indoor air quality. And it turns out that a lot of times cooking puts f very small particles fine particulates into the air that affects our our health and our lungs. And so having some sort of exhaust ventilation in your kitchen when you’re cooking is really important. And it turns out a lot of this research I was listening to from this from this scientist, Brett Singer was talking about just
How not only the the strength of the fan matters, just we shouldn’t be talking about CFM rates. We need to be talking about the location, the install, and the design of the hood itself, because that really has an impact. and so this is just a really important part of maintaining healthy indoor air quality that we’ve kind of looked past and not paid very much attention to. So I’m excited to kind of dive into this a little bit more and hear what hear what you’ve come across.
Reuben (06:52.867)
Yeah.
Tessa Murry (07:12.085)
with your recent research too.
Reuben (07:14.402)
Well, you know, it some of this is just it’s it’s based on blog posts that I’ve written on the topic. And like you talk about, I mean, CFM, the amount of air that it’s pulling out, all things being equal, a fan that pulls more air out is gonna do a better job of removing particulates. But before you even get into that, and that’s the one that everybody gets hung up on, is CFM. Yeah, I’m trying to say, but
Tessa Murry (07:40.459)
Yeah. How strong is it? Yeah.
Reuben (07:44.195)
There’s a lot of stuff that can be improved before you just go nuts with removing all this air. Cause you pay an energy penalty. I mean, for every cubic foot of air that gets removed from the house, you got a cubic foot of air of out outdoor air coming back in. And when it’s 70 degrees outside, it doesn’t really matter. But when it’s 70 degrees outside, you probably have your windows open anyway. And it’s not all that important. But when it’s
Tessa Murry (07:52.342)
Yeah.
Tessa Murry (08:01.25)
Yeah.
Tessa Murry (08:08.939)
Yeah. Yeah.
Reuben (08:11.894)
really hot outside or really cold outside, you’re you’re paying a big energy penalty to run that kitchen fan. And so, you know, just just cranking up the size of the fan shouldn’t be the first thing you think about. You think about design. And, you know, probably, I mean, think about thinking about a take a glass of water and then dump it into another vessel and put a big grate on top of that vessel.
Tessa Murry (08:18.498)
Yeah.
Reuben (08:41.74)
Well, if you want it to work really well, you’d have a big cone or you’d have a big funnel in this other vessel. So when you’re dumping your water, all that water is gonna go into your cone or into your bowl, and it’s gonna all get funneled inside of the vessel. Well, now turn it upside down. Now you got the bowl going up and you’re taking exhaust gases. What’s gonna work better? A bowl? A big old hood?
That comes down and and it gently slopes up, then you got a fan at the top of this inverted funnel. Or if you just got a big flat surface, what’s gonna work better? Well, you know what works better. It’s the upside down bowl, of course. And and which is gonna work better when you got an upside-down bowl in the middle of the room, like you got an island cooking appliance, like an island range.
Tessa Murry (09:12.176)
huh.
Tessa Murry (09:22.763)
Right, right.
Tessa Murry (09:36.35)
Mm-hmm.
Yeah.
Reuben (09:39.727)
Or is it going to work better if you put it up against a wall and that wall is going to contain a lot of this? Of course, that’s a better design. So the the more you can just use some common sense here, the the lower CFMs you need to achieve the same performance. When you’ve got a big scoop, it’s not located five feet above the range, and you don’t have it flat. I mean, if if you have a nice design.
Tessa Murry (09:48.726)
Yeah.
Tessa Murry (09:53.418)
Yeah.
Tessa Murry (09:59.671)
Yeah.
Tessa Murry (10:06.85)
Yeah.
Reuben (10:08.992)
You can probably have a 200 CFM fan and it’s gonna do all you need to do. It’s gonna do a really good job of removing all those cooking odors. But nobody wants that. I mean, everybody wants the bigger, the greatest, you know, they they go they like to go nuts with it.
Tessa Murry (10:19.734)
Yeah.
Tessa Murry (10:28.671)
Well, for context, Ruben, what what would you say is a typical range for CFM that you can get with different range hoods? If you’re if you’re installing specifically like a range hood for your kitchen, what size fans can you get out there?
Reuben (10:44.234)
I I I you know it Tessa, it’s been a while, and the last time I had this conversation with someone was with Patrick Brennan. I remember when he was in training and we were walking around together and we were talking about the average size. So this is this is probably 15 years ago that I last looked into it. Yeah, it’s so it might be outdated, but to the best of my recollection, I think we agreed that an
Tessa Murry (10:55.314)
yeah. Wow.
Tessa Murry (11:04.397)
A little outdated maybe.
Reuben (11:12.818)
average hood fan is gonna be somewhere in the neighborhood of about two hundred C Fm. That’s that’s a pretty typical average, I think. If I’m wrong, someone will write in and sternly correct it, I’m sure.
Tessa Murry (11:17.887)
Okay. Yeah.
Yeah.
I was kind of thinking the same thing. I you know, I was thinking 150 to 200 to e you know, and then you get to the really big whopping ones that people install, maybe commercial grade, which is like six or seven hundred. I don’t maybe even up to a thousand. I don’t know. How strong can they get?
Reuben (11:40.471)
I I’m sure. Yeah. Yeah. I I’m sure you could get them up. I I mean, I think the largest I’d probably inspect it was twelve hundred CFM. And you know, I I think it was like two six hundred CFM motors and you flip them both on and then you’re at twelve hundred. I mean, massive.
Tessa Murry (11:49.688)
my gosh.
Tessa Murry (11:56.666)
my goodness. Well, that’s that’s ridiculous. Like in your talking energy penalty, yeah, for every CFM that leave you know leaves the house, the house needs to pull in another the exact same amount of CFM from somewhere. So what do you do when you’re exhausting twelve hundred CFM of air when you’re cooking?
Reuben (12:15.234)
What do you yeah? You need a lot of air coming back in and it’s not gonna be a passive opening. You’re gonna well, you know what we talked about that one on the podcast. It was a couple of months ago where Mike and I were inspecting a big newer home and I was trying to figure out what this electric furnace was doing. And it turns out the whole reason they put the electric furnace in was just to supply makeup air. So when you turn on your kitchen hood fan.
Tessa Murry (12:19.469)
Yeah.
Yeah.
Tessa Murry (12:29.013)
Yes.
Tessa Murry (12:36.663)
Yeah.
Tessa Murry (12:43.597)
Cheated makeup air. Crazy. Wild. Wild.
Reuben (12:45.162)
It heats your air coming in. Yeah. Yeah. So so that that that’s a good example and it of not having just a passive opening. It’s powering that air coming in. So so what can you do before you get to that point where you get all nuts? You you have a nice design. I mean, just just think it through. Don’t have an island, put it up against a wall, don’t have it flat, have a big old scoop. All these things will help. So that that
Tessa Murry (12:55.638)
Yeah.
Tessa Murry (13:06.888)
Mm.
Reuben (13:13.868)
That’s a little bit about design. But then of course, you know, you’ve got the the fan, let’s say the fan is rated for 200 CFM. Are you going to actually get 200 CFM leaving your house? Tessa.
Tessa Murry (13:28.545)
Hmm. Probably not. Well, I’m just thinking the well, installation of the duct itself, duct losses, bends in the the vent the the duct, depends on how long the run is.
Reuben (13:32.278)
Why? Why? What expects it?
Reuben (13:40.329)
Uh-huh. Yep.
Reuben (13:47.875)
Yeah, yeah. I mean I I think the way it works is you get two hundred CFM right at the top of the fan with no obstructions. That’s the rating. But then as soon as you put your little restrictor on there, you’d you ’cause all all those things, I shouldn’t say all of them, most of them have a square opening and then we re we we change the shape to a six inch round duct. Sometimes you’ll have some square ductwork coming up, but
Tessa Murry (13:56.17)
Mm-hmm.
Tessa Murry (14:12.332)
Yeah.
Reuben (14:14.648)
The the best performance is going to be round. That’s the way air likes to travel. But when you have every every elbow you have is going to restrict airflow, it’s going to create turbulence. And the longer you run, the more turbulence. And then you’ve got your hood. Whatever you have at the outside, you’ve got a tight little hood that’s going to severely restrict airflow. You got a big, nice open hood, that’s a lot better. So
Tessa Murry (14:15.489)
Yeah.
Tessa Murry (14:19.563)
Mm-hmm.
Tessa Murry (14:27.467)
Yeah.
Tessa Murry (14:35.308)
Yeah.
Tessa Murry (14:38.935)
Yeah.
Right.
Reuben (14:42.476)
You have all of these different things that can reduce the performance of that fan. It’ll make just as much noise. It might be even noisier, but it’ll be less effective. So
Tessa Murry (14:51.893)
Well, and sometimes those dampers on the exterior vent terminals get stuck too. How many times have you know, you’ve been inspecting and you turn on all the all the fans when you’re walking through the inside of the house initially and then you go to the exterior and check those dampers to make sure they’re opening and they’re just they’re not. They’re s they’re s stuck closed or sealed closed or something too, or there’s a wasp nest that was built over it. Yeah.
Reuben (15:10.442)
All the time. Yes. I was I I was teaching a class out of town. I was staying at an Airbnb and they had a he had a kitchen exhaust fan. Well, and you know, let let’s let let’s make a distinction here. You can have a a kitchen fan, like you know, maybe a a microwave with a fan built in, and it might just recirculate, but it might exhaust to the outside.
Tessa Murry (15:33.965)
Mm-hmm.
Mm-hmm. Mm-hmm.
Reuben (15:40.238)
They’re not the same thing. We’re only talking about exhaust fan. The the ones that vent back into the house, worthless. What what’s the point of those?
Tessa Murry (15:49.229)
Face greasers, we call them.
Reuben (15:53.911)
Face greasers, I like it. Yes. They remove grease from down here and they bring it up here. But but the he he had a fan and I turned it on. I saw it vented to the outside. Because if it vents at the inside, I’m not even gonna turn it on. I don’t need it making noise. I I verified it vents at the outside. I turned the fan on. It didn’t sound right to me. I’m just like that I know this sound. This is the sound of air obstruction. So I went outside, there’s the terminal.
Tessa Murry (15:59.969)
Okay.
Tessa Murry (16:17.196)
Yeah.
Tessa Murry (16:20.619)
Yeah.
Reuben (16:23.878)
And it’s just old as dirt. It looked just super greasy. And the damper is stuck shut. Exactly what you decided. I kind of stuck my finger in there and I was able to pull it open. And then it stayed open while the fan was running. And it’s like, okay, I’ll I’ll leave it that way while I’m cooking. But then the next day I did the same thing. It was stuck shut again. It’s just super greasy. So I sent a note to the owner, said, Hey, thought you might want to know.
Tessa Murry (16:30.215)
Yeah. Yep. Yep.
Tessa Murry (16:40.599)
Huh.
Tessa Murry (16:48.328)
yeah.
Reuben (16:52.942)
‘Cause most people don’t know about this. They don’t know the difference in pitch on fans and they don’t take the time to check this stuff. But as home inspectors, we’ve heard it a million times. We know what this sounds like. Yeah. So
Tessa Murry (16:53.542)
Yeah. No, no.
Tessa Murry (17:01.139)
Yeah. Yeah. Yeah. Yeah. Yeah. That’s a good point. If you’re a homeowner and you have a fan, just turn it on and walk outside and make sure the damper’s actually opening when you while it’s on. Make sure it’s working. Yeah. Exactly. Especially if you’ve had a new roof put on recently. Sometimes those ducks can also get disconnected in an attic and maybe it’s blowing into your attic. Yeah. No. That’s bad news.
Reuben (17:11.586)
Yeah, yeah. Do this like once a year or something. You don’t need to do it all the time. Yeah.
Reuben (17:20.056)
Yes. They get disconnected if it goes to the roof. Yes. Yeah, you don’t want that. Yep. So that’s that’s some design from a home inspection perspective, you know, lots of times we’ll come across the microwave hood fan combination guy. And those things are designed to either recirculate where it blows back into the house or it blows up through the top.
The unit, and then you have ductwork coming out the top in the cabinet, or they vent straight out the back, and it comes through the wall. And in the case where I was staying, it was coming through the wall. But here’s here’s the thing: when you buy those, you’ve got this little squirrel cage fan, it’s this little square-shaped it square-shaped fan. And when it comes from the factory, it’s
Tessa Murry (17:57.483)
Mm.
Reuben (18:17.442)
I I think all of them are designed to point back into the house, recirculating. But then if you’re gonna exhaust to the outside, you got to take the fan out, you rotate it 90 degrees or 180 degrees to have the fan push the air a different direction. And we do many home inspections where people did that, it’s pointed the wrong direction, but then they don’t have any cutouts and it’s not doing anything.
Tessa Murry (18:23.149)
Mm-hmm.
Tessa Murry (18:27.97)
Mm-hmm.
Reuben (18:47.062)
So it it’s really loud, there’s a lot of turbulence, but nothing happens at all. And you know, I don’t care if you even use those or not, if it recirculates at the inside, but don’t have it pointed into a dead space where you’re just gonna accumulate a bunch of grease inside the cabinet, you know? So that that’s that’s something else we look at from a home inspection perspective. all right, anything else on that?
Tessa Murry (19:05.493)
Oof. Yeah. Yep. Not good.
Tessa Murry (19:12.331)
Not good.
Tessa Murry (19:17.183)
No, I was just gonna say, you know, what percentage of homes do you think that, you know, mm the we that structure tech and specs have kitchen hood vents, not the microwave vents or, you know, a recirculating fan, but actually have a hood vent that vents to the exterior. What percentage of homes would you say?
Reuben (19:17.23)
I think that was it.
Reuben (19:38.028)
the game tests. I mean my best guess would be 25%.
Tessa Murry (19:44.162)
Funny, I was thinking thirty. I and we might be way off, but I feel like there’s more homes than not that just, you know, don’t have proper ventilation for a kitchen range.
Reuben (19:46.305)
Okay. All right.
Reuben (20:01.484)
Yeah, yeah. At least or or maybe we should say not ideal ventilation, ’cause it’s not required by code.
Tessa Murry (20:05.833)
Yeah. Right. Which, okay, let’s just highlight that point. I think for anybody that’s listening, you know, we’re talking about air quality and and you know, the more research we do on indoor air quality, the more we realize, you know, how important it is to have some type of exhaust ventilation when you’re cooking because of these fine particulates that are that are created, with gas or electric cooktops from nitrogen dioxide, nitrite.
Oxide, carbon monoxide, all these bad things that get put into the air. We need some sort of you know mechanism to remove them. And because it’s one of the the worst sources of of pollutants for a home is cooking. And we do it all the time. And so it it’s crazy to me that it is not required by code, given all this research we have, to to have some sort of exhaust ventilation, especially.
Reuben (20:39.403)
huh.
Reuben (20:43.874)
Yes.
Reuben (20:56.187)
Mm-hmm. Yes. Agreed.
Tessa Murry (21:03.265)
if you have a you know a gas cooktop and how many times have Ruben have you come across, you know, a kitchen that has a gas range or gras gas oven and there’s no exhaust ventilation? I I’ve lived in plenty of places that have that setup and you know and I would test with my little personal carbon monoxide detector, the one I would clip on my belt and see, okay, well how much carbon monoxide builds up in the kitchen here in the house when I’m cooking something. And having the oven on?
Reuben (21:16.568)
Tons. Tons and tons and tons.
Tessa Murry (21:32.79)
for like 30 minutes. I I would have it depends on the oven, of course, but even in my sister’s house and her rental house, it was like 10, 12, you know, parts per million. Just having that that oven on for a little while. And I was like, D, you need to open up the windows and the door in here if you’re gonna be cooking. She’s got a small little kitchen. I was like, you won’t be breathing all this in. It’s only the numbers are only going up. And you got two little kids.
Reuben (21:55.907)
No. No.
Tessa Murry (21:59.382)
And so how practical is it to like have your windows open when it’s, you know, thirty degrees outside and you’re trying to bake something? It’s not. Yeah, but that’s what the code allows, which is crazy to me. Yeah.
Reuben (22:05.72)
No, no. But that’s what the code allows. The code says you need you need ventilation. Yeah. It doesn’t need to be a hood fan. It can just be a window. And yeah, I agree. It’s crazy.
Tessa Murry (22:15.949)
It is. So so Minnesota, can we dive into this a little bit more about, you know, what’s required and maybe some other some of your research too on what other states require for for ventilation? So Minnesota does not require this.
Reuben (22:28.302)
Sure. Well, well, no, mi I mean Minnesota requires the hood fan or an openable window. Yeah. Yeah. And I’m and I haven’t looked into what the national codes say, but I’m positive it’s the same thing. I mean, if you look up in the IRC, the mechanical code, I’m sure that’s what it says. So I don’t I don’t think we’re special there. Yep. Yep. One of the two.
Tessa Murry (22:36.117)
A window, an operable operable window. Right. Okay.
Tessa Murry (22:46.976)
Yeah.
Tessa Murry (22:53.355)
An operable window. Yeah.
Reuben (22:58.006)
So that’s what you need. And then and then what kind of prompted this is once you have that fan, how do you get air coming back in? What are the requirements? And I I used to hear it all the time is I’d I’d hear people saying, once you install a fan that’s 300 CFM or more, you need to have makeup air. It’s just it’s a code requirement. You need makeup air.
Tessa Murry (23:27.682)
Mm-hmm.
Reuben (23:28.102)
And that’s not right. In Minnesota, we we have a very complicated code. But before I get into the Minnesota code, let’s just talk about what the national code is. Because, you know, the way we get our codes is we take the IRC, the International Residential Code, and we adopt it. We say this is now going to be the Minnesota Code. And then when there’s areas where we feel like
It’s not good enough. We’re special here in Minnesota. We want to make changes to it. We chop it up and we make changes. And this is a really great example of Minnesota making some major changes to it because when you look at the national code, and and I I’m looking at the 2018 version, it could have changed since then, but I don’t think it has. the the the national version of the code.
Tessa Murry (23:59.288)
Yeah.
Tessa Murry (24:15.756)
Mm-hmm.
Reuben (24:24.022)
If you look at the mechanical section, it’s section M1503.6. It says where one or more gas, liquid, or solid fuel burning appliance. I’m reading word for word. Maybe I copied it down. It says appliance. I think it should say appliances. appliance that is neither direct vent nor uses a mechanical draft venting system is located within a dwelling unit’s air barrier.
Tessa Murry (24:39.671)
Sure. Yeah, not
Reuben (24:52.928)
Each exhaust system capable of exhausting in excess of 400 cubic feet per minute shall be mechanically or passively provided with makeup air at a rate approximately equal to the exhaust air rate. Blah, blah, blah, blah, blah. And then it says some other stuff. So to paraphrase, the national code says if you’re going to install a hood fan, that’s 400 CFM or more.
Tessa Murry (25:09.769)
Okay. Okay. Mm-hmm.
Reuben (25:21.632)
You need to have makeup air coming in, and the amount of air coming in needs to equal that of the air going out. That’s it. That’s the national code. I think it’s terrible. This is so woefully inadequate test. So you’re telling me you can take a super tight house, a small house, super tight, thousand square feet. It’s been air sealed, or it’s new, it’s been air sealed, whatever.
Tessa Murry (25:24.308)
Mm-hmm.
Tessa Murry (25:29.395)
Mm-hmm. Yeah. Yeah.
Reuben (25:51.267)
You can have a natural draft water heater and and you can install a three hundred seventy five CFM kitchen hood fan and you ain’t gotta do nothing. That’s it. That’s what the national code says.
Tessa Murry (25:55.959)
Let’s hope not.
Tessa Murry (26:05.207)
Process.
Tessa Murry (26:09.183)
Yeah. Yep, there’s there could be a problem there. There could be a problem.
Reuben (26:14.062)
Yeah. Yeah, I I don’t I don’t think that’s nearly adequate. Or on the flip side, you could have a big house. You could have a five thousand square foot house that was built in nineteen fifty and it’s leaky as all get out. And you you really don’t need makeup air. If if you do a really good calculation, you could have a ton of air leaking through your house.
Tessa Murry (26:33.142)
Yeah.
Reuben (26:43.77)
And that fan is perfectly fine, but you don’t inside you decide you want to install a 400 CFM fan, you still need to put in makeup air that equals the air coming out. So, I mean, it is just a absolute one-size fits-all approach, super dumb. And by dumb, I don’t mean stupid, I mean it’s just it’s not intelligent. it it doesn’t care about any factors. So
Tessa Murry (26:51.453)
Mm.
Tessa Murry (26:56.107)
Yeah.
Tessa Murry (27:01.898)
Yeah.
Tessa Murry (27:12.501)
Yeah. Well houses are yeah, houses are not not all the same. We all know that. And I mean some houses have natural draft or you know, maybe a wood burning fireplace or something like that where you need to take into consideration combustion safety. And newer houses and maybe houses that have been retrofitted don’t anymore. And so, like you said, it’s kind of silly that the code just lumps them all together under one rule. Mm-hmm.
Reuben (27:13.41)
That’s the national code.
Reuben (27:39.331)
Yeah. Yeah, exactly. And you know, in in the in the thing I described with this very small tight house, you put that kitchen hood fan in and you have a natural draft water heater, I I mean, I I think most of our listeners already understand what’s gonna happen, but Tess, what’s surely going to happen?
Tessa Murry (27:58.424)
Mm-hmm.
You’ll probably back draft that water heater. I mean, you you’re you’re pulling in air from the path of least resistance to make up the air that’s leaving and being exhausted. And that B vent or that vent for the water heater is a nice pathway to the exterior for air to come in. And so it’ll just pull air down that down that chimney. And what can happen is if that water heater is firing or running, you’re just pulling all those exhaust gases right back into your house.
Reuben (28:31.712)
Yes, yes. And I’ve I’ve been in that situation where I’ve even had natural draft furnaces backdrafting. I mean, tons and tons of bad gases coming into the house. Yep. So the one size fits all approach I don’t like at all, but in Minnesota, we made it super complicated.
Tessa Murry (28:32.289)
Not good.
Tessa Murry (28:39.834)
E o yeah. Not good.
Not good. Not good.
Tessa Murry (28:57.355)
We went the other direction.
Reuben (28:59.258)
Yeah, and again although I’m not gonna say it’s a bad thing. I kind of like what Minnesota did because this is complicated. And I mean it’s not like I don’t know. I think Minnesota may have made it more complicated than it needs to be. I mean, they the the whole code could be rewritten in a way that’s a lot easier to understand. And I’ve blogged about this a couple of times, and I’m gonna do another blog coming up pretty quick here because.
Tessa Murry (29:06.923)
Uh-huh.
Tessa Murry (29:20.875)
Mm-hmm.
Tessa Murry (29:27.52)
Okay.
Reuben (29:28.756)
I I frequently get people writing into us saying, Hey, can I hire you to calculate how much makeup air I need for my house? Or a more common question people ask, they say, I want to hire you. I mean, I saw your blog post, but I can’t figure it out anyway. And they say, What’s what’s the largest fan I can put in my house before I need makeup air? That that’s another
Tessa Murry (29:44.139)
my gosh.
Tessa Murry (29:50.241)
So
Tessa Murry (29:57.286)
huh. Wow.
Reuben (29:58.861)
Common question people have. And so I I used AI a little bit and I programmed in a lot of inputs and I made a calculator for Minnesota homeowners to determine the largest fan they can put in their house without needing makeup air. Pretty cool. Yeah.
Tessa Murry (30:15.799)
Reuben. This is very exciting. I was gonna say you you could have started a little side hustle there. Now this is a free tool. Are you is this gonna be available online?
Reuben (30:22.182)
I know, right? And I yeah, of course I’m not gonna charge for it. It’s a free tool. Yeah, yeah, it’ll it’ll be it is available online. I’ll have a link to it in the show notes. And so we’ll just call it the the max CFM allowable for Minnesota or something like that.
Tessa Murry (30:34.739)
Wow.
Tessa Murry (30:39.917)
This is exciting, Ruben, because I remember having to pull up your blog several times, read through it carefully a few times to then try and answer those questions that people had. You simplified it. Yeah.
Reuben (30:52.374)
Yeah, it’s it it makes it way easier. And basically what I mean you still need to know a little bit about your house. You need to know how many appliances do you have that are feeble. I mean, if if if all you have is direct vent appliances, meaning they take all their combustion air from the outside and they vent everything back to the outside, it’s that’s great. That’s the best case scenario.
Tessa Murry (30:59.893)
Mm-hmm.
Tessa Murry (31:06.922)
Okay.
Reuben (31:22.44)
If you have power vent appliances, that’s basically the same thing. We’re not worried about those backdrafting. But you if you have a fan assist appliance, like a lot of furnaces before they went high efficiency, they’d have a little fan that sucked the exhaust gases out. If you have one or more of those, you gotta you have a little bit of a penalty. You don’t get to have as big of an exhaust appliance.
Tessa Murry (31:33.133)
A system finds
Tessa Murry (31:40.918)
Okay.
Tessa Murry (31:49.355)
Hmm.
Reuben (31:52.449)
If you have a natural draft appliance, like a natural draft water heater, you pay a bigger penalty. If you have more than one, you pay an even bigger penalty. So it’s you got to figure out which category am I in? You’ve got those four categories to choose from. So you got to figure that out on your own. I’m not coming to your house to figure it out. And then you need to figure out the total square footage of your home.
Tessa Murry (31:57.42)
Mm-hmm. Yeah.
Tessa Murry (32:04.289)
Mm hmm. Yeah.
Tessa Murry (32:12.363)
Yeah so yeah.
Reuben (32:20.628)
Once you have those two, you can figure out what the max CFM is. And and also you got to figure out the year built, I think. And that’ll change it. But you get couple little pieces of data, and it’ll tell you this is the max size you’re allowed to have before you need makeup air. However, the Minnesota code says, you know, the reason people get hung up on this 300 CFM is that the code says.
Tessa Murry (32:20.994)
Mm-hmm.
Tessa Murry (32:27.5)
Mm.
Okay. Yeah.
Tessa Murry (32:42.348)
Yeah.
Reuben (32:50.688)
Anytime you’re installing a fan that’s 300 CFM or more, you need to do a calculation.
Tessa Murry (33:00.129)
Uh-huh. Okay.
Reuben (33:01.686)
It’s not saying you need to put in makeup error, but you need to check. You need to make sure you’re cool. So you can install a 250 CFM fan in any home, which I’m not a huge fan of. I mean, I I think like you ought to be doing a calculation at any stage, probably, just to be safe. But this is what the code says: 300 CFM, you got to do your calculation. So I I I created a second calculator because this is only
Tessa Murry (33:03.885)
Right.
Tessa Murry (33:19.691)
Yeah. Yeah.
Reuben (33:31.673)
Part of the equation. This is the easy part to figure out what’s the big biggest fan you could put in. But if you do need to have makeup error, I mean, let’s say you have a small house or you know, a really tight house, whatever, or you got some feeble appliances, you’re gonna need to do this calculation. It’s a lot of different things you need to look at. It it gets really complicated. And then
Once you have a number, it says, okay, here’s how much makeup air you need. Let’s say you need 100 CFMs of makeup air coming in. Well, okay, what do I do with that? How do I get to 100 CFM coming in? Well, there’s another chart, there’s another table. And then you got to look at which column in the table you fit into based on the appliances I described. And then you need to see how many CFMs.
Tessa Murry (34:12.417)
Yeah.
Tessa Murry (34:23.053)
Yeah.
Reuben (34:25.334)
And then it’ll tell you the size of the duct you need. But then there’s a footnote at the bottom that says this chart assumes you’re using rigid ductwork. And nobody ever uses rigid ductwork. Everybody uses flex insulated ductwork. Then it says you need to step up the duct by one size, and you need to increase it by an inch if it’s flex, which it always is. So it’s all these different things. So I made another calculator, and of course, I used AI for this.
I think I told you that. I can’t take all the credit, but I was just crazy impressed with what a nice spreadsheet AI made for me. And I tested a bunch of sample numbers where I had already done the calculations myself. And then I fed them into the AI, and everything is just, you know, it’s spot on. It’s perfect. So so the way it works is you type in, all right, here’s here’s the age of my house, here’s the appliances that I have.
Tessa Murry (34:56.437)
Mm.
Tessa Murry (35:04.14)
Wow.
Tessa Murry (35:09.324)
Yeah.
Tessa Murry (35:13.203)
Wow. Wow.
Reuben (35:23.032)
Here’s the CFM fan I’m going to install. And then it’ll tell you you need combustion air, and here’s the size duct, or you don’t need combustion air. So it it removes a lot of these steps. And I yeah, I think it’s really neat. And it’s like there ought to be something put out by the building inspections department or something like that, just to make it this easy for everybody.
Tessa Murry (35:37.247)
That’s cool. That’s really cool, Ruben.
Tessa Murry (35:50.05)
Thanks
That’s you’d think. You’d think. It’s a much needed tool for sure. and I’m surprised no one has created something like this before. So thank you. On behalf of on behalf of us regular citizens here who don’t like to do math or read the code with a fine tooth comb. Thank you so much.
Reuben (36:02.946)
Yeah. Or
Reuben (36:11.594)
I know. Yeah. Well, and I and it every time somebody would write in, it’s like I I could I didn’t want to charge them for it. And I thought, I know how this works. It’ll take me five minutes. I’m just gonna do it. I’ll give the answer. I d I would. Because I couldn’t charge people for it. You know. stop.
Tessa Murry (36:20.949)
Mm.
Tessa Murry (36:25.589)
You would? Ruben. Gosh. You’re such a good person. Yeah, I you know, there were several times I’m like, read this blog here. Go read this blog that Ruben wrote.
Reuben (36:37.23)
Yeah. Yeah. Yeah. But now you can still still direct them to that blog, but it’ll it’ll give them the calculation now. So makes it a lot easier. So that’s that’s where we’re at. But I mean, yeah, I just I can think about so many scenarios where the the national codes are not adequate. And there’s even scenarios within the Minnesota code, like I talked about. I mean.
Tessa Murry (36:45.138)
Wow. Wow. That’s great.
Tessa Murry (36:58.261)
Yeah.
Reuben (37:03.5)
You could install a 250 CFM fan and you could screw up your appliances. But you know, there is something else I found interesting. And in prepping for today’s show, I was doing a little bit of reading on what Minnesota requires. And they say that instead of installing makeup air, you do have a couple of other options. They they they say the the exceptions, they say makeup air is not required.
Tessa Murry (37:07.947)
Mm-hmm.
Tessa Murry (37:27.81)
Hmm.
Reuben (37:33.089)
When any of the following are demonstrated, and they got two options for you here. And where’d you go on my screen? I’m trying to find this. I lost your test. That’s okay. number one, you do a test spillage is performed according to ASTM standard, blah blah blah. I’m not gonna read it all. I looked it up, I thought maybe I’ll get this test standard. It’s $96 to purchase a copy of this standard. Not gonna do it.
Tessa Murry (37:38.422)
Okay.
Tessa Murry (38:02.453)
What? Cheese.
Reuben (38:02.646)
So I don’t know what it says. So there’s that. Or number two, a test approved by the building official verifies proper operation of vented combustion appliances. What do you think about that?
Tessa Murry (38:18.633)
Okay. Sure. Yeah.
Reuben (38:22.934)
Okay, so Tess, you’re the building official. Someone is coming to you and they say, Well, I want to do a test that you will approve. What’s your test gonna be?
Tessa Murry (38:34.829)
Let’s turn on the fan and see if anything backdrafts.
Reuben (38:42.439)
Yeah. a well, and and the kitchen fans and the dryer.
Tessa Murry (38:46.559)
Yep. Worst case depressurization tests. We can run that.
Reuben (38:48.27)
And depressurization, close the make sure all the windows and doors are closed. And turn on the furnace’s blower fan, probably.
Tessa Murry (38:54.677)
Yeah.
Tessa Murry (38:59.359)
You know, there there’s a lot of nuances there, Ruben. We won’t get into it. BPI has standards on how you need to set up the house to make sure that you’re putting the Cas Zone in the in the most negative possible state, negative pressure that you can. And it’s yeah, it’s all those things. Yes. Yes. Yes. Yep.
Reuben (39:06.766)
Yeah.
Reuben (39:13.002)
We’re doing some basic stuff here. I mean, you can flip these switches. Yeah. So you do all that. Would you be cool with that? I’d be cool with that. Yeah. Yeah. So there is an exception in the code. If you’re I mean, if you’re installing a big honkin fan and you know your house is kind of leaky, and you’re thinking, I just don’t need this. Well, maybe you can go to your building official and say, Hey.
Tessa Murry (39:22.519)
Sure. I would. Yeah.
Tessa Murry (39:30.4)
Okay.
Tessa Murry (39:40.086)
Yeah.
Reuben (39:43.288)
How about you allow me to use exception number tool? I exception number two under section five one point four point three. Propose that to them. Yeah.
Tessa Murry (39:47.799)
Mm-hmm.
Tessa Murry (39:53.198)
There you go. They’re gonna hate you, Ruben. And also I would think for liability reasons, if someone like dies because of carbon monoxide poisoning later and they didn’t have makeup air installed, it’s coming back on you as a building official that approved it, maybe. So they might require some sort of like BPI certified tester to come out and actually do all of that, which would cost you additional money anyways.
Reuben (40:15.406)
Sure.
Reuben (40:19.052)
Yeah, yeah. And and at that point it’s like, why don’t I just put in the makeup deduct? Yeah. Yeah. Okay. All right. that was everything I wanted to talk about. Did we miss anything, Tess?
Tessa Murry (40:21.963)
Yeah. Just do it. Yeah.
Tessa Murry (40:31.997)
No, I I don’t think so. I you know, I was just kind of looking over some highlights from some of Brett Singer’s research and studies and and you know, he was agreeing with kind of some of the things we said earlier and and I had a a moment to kind of quick quickly read through your your newest blogs on this, but just the importance of of basically
People just people might have an exhaust fan that vents to the outside, but they don’t use it. So making sure you actually turn it on before you start cooking, have it run and leave it on for a few minutes afterwards. And to use the back burners, because it’s the the the way the hood vent is designed, it will capture better if you’re using the back burners instead of the front burners. So if you can do that. and the importance of having some sort of
Reuben (41:02.348)
Mm. Yeah.
Reuben (41:13.184)
Yes, great point. Yes.
Reuben (41:20.973)
Uh-huh.
Tessa Murry (41:26.265)
a hood vent that’s quiet too, because if it’s loud, people will tend to not use it as well. So I know you mentioned s I think sewns in your blog. I think Brett Singer said less than two sones at at normal speed is good. I think you might have said something like three less than three sones is important so that people will actually use it. and that Yeah, yeah, it’s annoying. No one wants to have this really loud hood vent.
Reuben (41:31.096)
Yep, yep.
Reuben (41:46.402)
Yeah. ‘Cause if it shows out conversation, it’s it’s obnoxious. Yeah.
Tessa Murry (41:54.028)
He also talks about how like the microwave vents are not as effective as an actual capture, you know, hood. like you were talking about this the shape of it, the bowl. so yeah, there’s just a lot of a lot of kind of just common sense points that you know you are important, but we tend to overlook them or not discuss them. So yeah. We actually have we have a microwave vent that vents to the exterior.
Reuben (42:00.471)
Uh-huh.
Reuben (42:15.532)
Yeah. Do you have a hood fan at your house, Tess?
Tessa Murry (42:24.031)
And it’s loud. but we use it. And we also have another
Reuben (42:24.15)
Okay. Okay. Do you use it every time you cook or just when you burn stuff?
Tessa Murry (42:30.525)
No. You know what, Ruben? I wish I could say I used it every time I cooked. I use it more than just burning things, but ’cause I never burn anything, but no, but I I use it when I’m doing stuff on the stovetop and it’s and I and I’m cooking on the stovetop. I don’t use it when I’m baking anything usually.
It’s an electric range, but I know that I’m still creating fine particulates and other things. So I I try and put it on a a low speed. But honestly, it’s it’s a microwave vent and I’m usually cooking on the front burners on a low speed. So how much is it actually helping? It’d be interesting to do some testing and see if it’s actually doing anything at all. It’s probably not. Yes. And on high speed.
Reuben (43:14.124)
I needed to start cooking on the back burners.
Reuben (43:19.532)
Yeah, yeah, yeah, yeah. Yeah, exactly. Yeah.
Tessa Murry (43:20.557)
Yeah, there will be no conversations in the kitchen while that thing is on. No, but it’s actually, you know, it’s funny. I try not to burn things because we have a photoelectric smoke alarm that’s right outside the kitchen and it is so sensitive that it goes off all the time.
Reuben (43:35.842)
Wait, photoelectric or ionization did you mean?
Tessa Murry (43:39.903)
I think it’s I think it’s photoelectric anionization. I’m gonna double check that. ’cause it’ll go off when there’s no smoke in the air.
Reuben (43:44.567)
Okay.
Reuben (43:50.988)
Hmm. That sounds like ionization.
Tessa Murry (43:52.532)
Zero smoke. It might be. I need to double check on that now. Anyways. It’s it’s super sensitive. I will. I will. We actually took it down last night because it went off twice while we were cooking, so
Reuben (43:57.583)
All right. All right. I’m please report back. I need to know. Okay. All right.
I’m gonna pause the show. Go check. No just kidding. All right, I’ll try to remember to ask you about that next time.
Tessa Murry (44:12.041)
know where Andrew put it. He got so mad at it the second time it went off, he just ripped it out. He he unplugged it. He took it.
Reuben (44:19.31)
That’s what people do. I’ll bet you it’s ionization.
Tessa Murry (44:24.237)
It you know, it might it it probably is. I was thinking it was both, but it’s it’s probably ionization. Yeah. It goes off too much. Anyways, anywho, we sat on a little tangent there, but yeah. I think those were the the main points and you you covered a lot of them. It’s about good design and and the capture efficiency, not so much the CFM rate that it pulls out. That’s important.
Reuben (44:30.153)
Photoelectric doesn’t do this.
Okay. All right.
Reuben (44:39.331)
Yeah, that’s okay.
Reuben (44:52.44)
Yeah. Yeah. And yeah, I I’m very aware of this because I mean I’ll probably mention it. I steam broccoli just about every morning for breakfast. I’m still doing it. And but it’s like I use the back burner because I want it I want it all caught. And I turn that fan on the highest. I got a turbo setting I turn it to, and it stays there because it I mean it makes the whole house stinky. I mean, really stinky.
Tessa Murry (45:02.314)
are you still doing that?
Tessa Murry (45:08.673)
Yep.
Yep.
Tessa Murry (45:17.246)
I was gonna say, I’m sure your family doesn’t wanna be smelling like broccoli all day. So
Reuben (45:25.612)
No, nobody appreciates that. So, you know, putting it on the back burner, putting fan on high, all that, that’s the best I can possibly do. But it it really does make a difference whether it’s on the front or back burner on how much you’re collecting. Yeah. Yep. Good point.
Tessa Murry (45:39.906)
Yeah, how much it gets. Uh-huh. For sure. I remember there was a a very airtight house I was doing a blur door test on way, way back before I worked at Structure Tech. and it was a it was a actually a uniquely built panelized house. So it it was a studless wall system. And the houses were pretty small, but I wanna say the ACH fifty of these houses was like point three.
ACH 50. So like so for reference, like code in Minnesota requires a three air changes per hour or less for new construction. So this house was 0.3. So so almost like passive house standard, right? And it had they hadn’t quite figured out yet how to do the ventilation in this house. And so the the it was a four stair sealed combustion furnace.
Reuben (46:21.006)
Crazy.
Tessa Murry (46:37.489)
I believe there was an air exchanger and then there’s just a a passive makeup air duct coming to the basement, six inch, you know, flex duct. And there was a a range hood. And I remember I was getting coming in and all this house and I was turning on all the vent fans and I had the I turned the the kitchen cooktop fan on and the front door I hadn’t latched the front door properly and the front door just phom.
flung open. As soon as I turned on the kitchen exhaust fan, I was like, Whoa, this is a tight house. I could almost do a you know, an infrared test of the building envelope with just using the kitchen exhaust fan because it was so tight. Yeah. Yeah. But I don’t believe there was any sort of Yeah.
Reuben (47:04.578)
Yeah.
Yes. Yes.
Reuben (47:17.376)
totally. Yeah. Yeah. Absolutely. Yeah. I’ve been in houses like that where it’s like you you give it a you give it a slam and it’s almost comical where it gets really close to closing and then it bounces back open.
Tessa Murry (47:30.477)
Yes, pops back open. So I I just remember that thinking, my goodness, wow. It’s a strong strong exhaust fan. But I mean it was normal exhaust fan, just a very airtight house, you know? Yeah. So kind of fun. Kinda fun.
Reuben (47:42.85)
Yeah. Yeah. Love it.
Reuben (47:49.71)
All right. Well, I think that’s it for today. We’re not done on our topic of new construction and cosmetic defects. We have more on that. I’m gonna have some guests come on pretty quick here. I’ve got some lined up for the future.
Tessa Murry (47:59.473)
Might recall. Yeah. Well and thank you, to our listeners, everybody that that that tuned into that episode. We’ve had a lot of a lot of interesting responses. Like you said, Ruben, we’re not done with this. Yeah, we’re not done. It’s it clearly is a topic a a heated topic right now, I think, in the industry. And so there’s a lot of people that are running into these challenges and have their own opinions on it too. And
Reuben (48:14.828)
Yeah. A lot of good responses. No.
Tessa Murry (48:28.501)
have unique experiences. So I’m excited to kind of have have this guest on that you you’re talking about.
Reuben (48:33.826)
Yeah. Yeah. At least one, maybe more. We’ll see.
Tessa Murry (48:38.189)
Cool. That’s cool.
Reuben (48:40.239)
All right. Well, thank you, Tessa. Hope you’re still around when we do this. You surely will be. You won’t be on my journey leave that early. Yeah. Yeah. It’ll be soon. All right. Well, for our listeners, you got any thoughts, questions, comments, whatever, reach out to us. We love hearing from you. Love reading the emails. It’s podcast at structuretech.com. And we’ll catch you next time. Take care.
Tessa Murry (48:44.715)
Me too. I hope so. In the next few weeks, hopefully, we can get him on. Yeah.
Tessa Murry (49:06.242)
Thank you. Bye.