Can A House Be Too Tight - ERV Fresh Air Experiment

[@videozoom12]

I think I’m good with opening and closing my windows. Sure Texas you keep your windows closed 10 months of the year but it certainly beats spending a couple grand on a system that will break.

[@buildshow]

If you’re a resident of San Diego this comment makes sense but if you’re a Texas resident you’re willing to spend the money on a comfortable house. It’s HOT and Humid here. Add in bugs, mold, pollen, oak fever, cedar fever, etc and you’ll want a tight house with a good HVAC+D system

[@videozoom12]

@ I do agree largely with your response. And yes, opening a window does zero favors with humidity. I guess I’m attracted to the simplicity of opening and closing a window. I guess I have greater faith in my arms and WD-40 than I do an entire extra add on. Ty for the kind response of course. I live in San Antonio.

[@rykdheiner]

I drive luxury cars because they’re comfortable and perform well, are there more potential points of failure? Sure but the added cost is worth it, look at long term cost, less doctors visits, asthma attacks, seasonal allergies, cost of medicine…

[@videozoom12]

@@rykdheiner very well said and never fully thought through! While in high school I did check myself into the ER for respiratory distress during a bad cedar outbreak while training in Helotes, just outside San Antonio. Ty for the additional comment!

[@jundossantos]

Sure, an ERV can break, but I think you're overestimating how complex one is. An air conditioning unit is vastly more complex and yet most Americans can't live without it. That's why HVAC companies run 24/7. The only mechanical part of an ERV is the intake fan and outtake fan. And then there's the cpu, but nowadays those are built to be pretty robust and replaceable. And operable windows is basically the failsafe for a broken ERV. Sounds like a no brainer to me.

[@dreednlb]

0:32 " 'If you fart in that house you're going to smell it a week later.' Kind of a crude comment" 7:28 Literally labels the switch "FART FAN" 😂

[@UriahtheHittie24601]

You have sold me on the ERV system and passive house! YOU'RE CHANNEL has changed the way i look at constrution! It makes perfect sense! I will not settle for nothing less on my future build.

[@yolo_burrito]

Matt’s house: so tight it’s basically a passive house. Also Matt’s house: Aesthetic of a generic mid aughts hotel lobby.

[@mikeyfoofoo]

Our methane/gas detector went off once in our bedroom. We had an infant at the time. I called the fire department at 6:30am thinking something was wrong with our furnace. They found nothing. My wife had farted in the bed a few minutes before it went off. I couldn't imagine a fart could set of an alarm but that's the only thing that could have done it. I occasionally bring it up that the fire department had to come her fart was so bad. Ten years later it still annoys her if I bring it up, but it's funny to me. ; )

[@cpad007-]

I didn't know women farted! ;o) lol

[@mikeyfoofoo]

@@cpad007- The flatulence is real! : )

[@DoNotEatPoo]

@@cpad007- They don't, it's usually a puff of glitter

[@Stefandeseve01]

It sure made it easy to weed out contractors. Contractor: "If you build it that tight you won't be able to breathe." Me: "Next."

[@shellderp]

every HVAC contractor tells me something different about ERVs, its so tiring

[@Ariccio123]

The issue is I end up with nobody left this way 😆

[@JeremyBell]

If you got the money then by all means go for it. But if you mess up a "tight house", then you will have catastrophic problems. Which means you'll need to find a specialist builder (not your average builder). Which means a premium price for the design, labor, and materials. Yes, we all want a Ferrari, but if you have a Honda budget, then we just want a car(house) that gets the job done.

[@colinstu]

@@shellderp everyone just wants to sell whatever pile of crap they have, whatever they can shill and move the quickest. Cannot stand how this industry is.

[@Ariccio123]

@@JeremyBell uh if you mess up a drafty house you have problems too We usually just cover those problems up by throwing energy at the problem

[@davidgustafson4563]

In the 90s code in my area required a fresh air intake on furnace returns. This was for radon gas. This is a good way to bring in fresh air, and pressurize the house to reduce drafts as well as provide make up air. I run my furnace fan 24h and it keeps my leaky house fresh. Not as energy efficient, but an effective solution to air quality issues.

[@Allen-w9d]

Some people hear the words "tight house" and then their minds shut down and refuse to hear the words "air exchanger" to justify their criticism that the house can not breath when you build the tight.

[@kevinstenger4334]

I’m impressed, not once did I hear anyone knocking on the door asking what’s taking you so long in there. The other thing I noticed is that you have a lot of shoes. I wish every house could have a nice system like yours.

[@DetailCarPro]

Matt, you might want to do a video or comment on this one on how HUGE of a difference this makes in keeping house clean as well. The amount of dust that gathers in a well built house like yours vs a standard builder house is a huge difference. Less alergies as you alluded to, but less work to maintain as well. My2CentsWorth.

[@KevinLyda]

I live in Ireland where it's wet and cold in winter. Well, wet and colder. I would wipe down the doors and windows with a weak bleach solution every few weeks in winter before I installed an HRV system. It was the only way to stop them from being covered in mould and mildew. Now, with the HRV system, I really only need to do it on a sliding glass door that has metal frames - and only like once or twice over the whole winter. The PVC windows are fine - though the HRV system does nothing about dog nose prints. Still stuck cleaning those!

[@kirkwilson5905]

Much of the average household dust is actually human generated.

[@volksbugly]

Love this! I live in, "I hate saying this." a builders special new home. I wanted to retro fit a fresh air system, but there are to many hurdles. So what I've decided to do is to seal the house the best I can, but then retrofit a MUAS. We have our kitchen fan and 3 additional fans. I plan to insulate all the outlets/switches, pull off the base board and caulk floor to drywall with big stretch then put the baseboards back on, not ideal but its the best bandaid I can do.

[@Sean084]

In AUS we call them MHRV. They’re pretty rare over here. Majority of people seem to be happy living in glorified leaky tents. How you build daily is a ‘specialist’ thing over here, which is also what we do. The Zehnder systems are not cheap but by far the best. All of our clients report improvements in allergies, hay fever & asthma. Also mention generally feeling and breathing better when these units are installed. First hand, airtight homes feel different. They feel healthier, it’s a bit strange at first but unbelievably noticeable. None of our clients have regretted spending the money on these systems. Great Vid Matt

[@danielstover3029]

Way to go Matt! What a headline! The trolls will have a go at this one. It's sad that they don't seem to understand controlled and conditioned air space. It sure is nice to have clean filtered air and the ability to open windows and doors. Great video. I laughed a lot watching and even more reading the comments. Thanks for sharing... 😁👍

[@buildshow]

Appreciate the support my friend!

[@danielstover3029]

@buildshow Tell the truth and the truth will set you free... 😁👍

[@jasonbroom7147]

If he'd opened a window in the bathroom (which doesn't have one?) the situation would have been cleared a helluvalot faster. Matt obviously believes there is a problem to be addressed, or he wouldn't have labeled the switch the way he did. ;)

[@jonk3529]

Rev Matt!! I haven’t commented in awhile! Appreciate the good work brother!

[@jasonbroom7147]

So, you spent a lot of money to make the house "tight", then spent a lot of money to get stale air out of the house, and finally spent a lot of money to bring fresh air into the house. Sounds really efficient. My $80 bathroom exhaust fan and an open window would have taken about 90 seconds to do what your "system" couldn't in 20 minutes. That's just nutty.

[@amitsamra1937]

I don't like how you're using a fog machine for this test. Much prefer the traditional method: chimichanga, beans and nachos.

[@illeatmyhat]

this is my swamp

[@youdontknowme5969]

a delectable mix of Taco Bell & White Castle 😏💨

[@Motivation-qf5gg]

Broccoli, chick peas, beans and boiled eggs in a salad and your in-laws will never visit you again.

[@jmbpr1v8]

Matt, when you closed the door to your bedroom, you restricted-to some unknown degree-the makeup air to your test area. Remember the original lack of makeup air for your kitchen hood? Perhaps a better test would be to: 1) Open all the internal doors typically left open in your house. 2) Turn off the ERV. 3) Fog the house. 4) Turn the ERV back on & time the clearing process. Hope that this is helpful. I always enjoy your videos and have done so for many years. Best wishes.

[@YWWaT]

Passive House Consultant here- to answer your closing question, the fogger + a blower door adding pressure to a traditional house would show where the infiltration's happening, just in reverse

[@umeng2002]

I've finally moved into a house with a fresh air system. It's not as fancy as a Zehnnder, but it does make a difference. It's never stuffy.

[@ustopian]

For the last 5 years ive felt these houses were too tight. This really opened my eyes.

[@dannyomo]

maybe set up some foggers just outside of where air would typically infiltrate and put the house under negative pressure to see where it comes in through. nice video :)

[@MrMoparMan]

It's funny that people have said forever that a house needs to breathe, they just never thought to give it lungs! Controlling airflow is huge, great test! Maybe fog the whole house during a blower door test?

[@doobiedoghousewilson]

One of the advantages of the Energy Recovery Ventilation system is - energy recovery! (Of course, but it didn't seem you emphasized this.) The leaky house has no exchange of heat between the fresh and exhausted air - dumping conditioned air outside and bringing in unconditioned air that will have to be fully treated. Sorry if this is too obvious. Are there estimates on the thermo efficiency?

[@tealkerberus748]

Leaky houses generally don't have properly conditioned air. It may be warmed or cooled, but it's a complete waste of time to try to filter the dust out of it, and not much more useful to try to manage its humidity.

[@TheWineroute]

This is huge in norther climates interior moisture will condense on windows and rot them from the inside. I have a HRV on a super tight house, works great.

[@patrickkenny2077]

Just do a positive pressure blower door test on a fogged traditional house, Matt. I live in a naturally ventilated house; we have air conditioning in the bedrooms, but the moderate climate doesn't need much. I still wish the house was tighter though; it would make humidity control so much easier and help in dealing with outdoor pollution when it is an issue. Not sure how we would work the operable walls though.

[@thebuildreview]

Maybe your referenced comment was from someone who wasn't considering the additional implementation of a good air management system. For example, there is a call for airtight homes in New Zealand's building code, but no requirement for any air management systems, which causes a big moisture management issue. Maybe Matt, you could do the same test with your air management systems turned off....

[@rustknuckleirongut8107]

A friend of mine rented an apartment that was under a year old and found that mushrooms started growing in the window sills because the system could not handle a window being opened. It was too air tight with a system that needed the house to be permanently sealed from the outside other than just opening and closing the entrance door. The problem with houses being built like that in Norway is that no one is used to living like that. We all love opening windows and having the balcony door open in the summer. This means disaster for many homeowners that move into a home expecting the freedom to live as they wish rather than being stuck inside as prisoners to a ventilation system.

[@tealkerberus748]

@@rustknuckleirongut8107 Also, if your air system can't handle a bit of moisture like that, what's it doing with the carbon dioxide?

[@whoops655]

Use black lights to make the fog glow. Also there is concern about opening the bathroom door to the bedroom during the test. This allows a rush of fresh air from the bedroom to mix with the bathroom without truly being sucked out of the exhaust.

[@publicmail2]

Depends on the Fart, now my Wife for example...

[@Perfectguns89]

I think that because there were no fully waterproof building materials or methods, houses used to be designed quite leaky and allowed enough air movement to dry out anything. Later, combustible heating systems made it possible to keep your home warm at a reasonable cost, so it didn't really matter if it was leaky or not. Since everything has become so costly these days, it makes sense to have a very tight home to stop the elements from controlling the amount of air that passes through my walls. Before spray foam and drywall, I built my house with an ACH50 of about 1.1. My electricity cost is equivalent to that of my neighbour across the street, whose house is 35% smaller. Telling my house how much air it needs is preferable to Mother Nature suckling away all of my heat. I had to have a central dehumidifier installed since the darn dampness had nowhere to escape. That's my only grievance. I live in Canada's north, where nighttime temperatures can drop to -40°C or -40°F.

[@alberthartl8885]

An infrared camera can show where a traditional house is leaking. Just turn on a couple exhaust fans and scan the perimeter of the house. No smoke 💨 required. (You can get an attachment for a smartphone.)

[@tealkerberus748]

My parents used to have a house that had air conditioning outlets in the bedrooms and an extractor fan in the bathroom. The cold draught under the bathroom door straight on my wet toes was brutal, and you couldn't sleep at night unless the bedroom door was wide open because the air con couldn't push cool air in against a shut door. If they'd cut an inch or two off the bottom of the bedroom doors it might have worked, but then even closing the bedroom doors wouldn't have given anyone any acoustic privacy. I'm a big fan (pun intended) of changing our house designs from the ventilation strategy of a tree to the ventilation strategy of a lung. I'm tired of dust and bugs entering the house through all the gaps where "fresh" air is allowed to seep in, and I want my indoor air to be at a controlled temperature and humidity all year around. But a lung can't function without stale air being piped out and fresh, filtered, conditioned air being piped in, and that doesn't just mean for the house as a total - it means every room that you can close a door on, you need to pipe air out and you need to pipe air in to that space.

[@timdestasiohvac]

The difference in mechanicals needed for a 3 ACH50 house and a

[@mattcantrell5640]

Is there a point of air exchanges (leakage) where the ERV becomes a necessity? Say you improve a leaky house down to a blower door score of 5.0 or 4.0.....or even 2.0. When do you decide that the ERV is necessary?

[@ValentineFarm]

Absolutely spot on! Thank you. 😁

[@youdontknowme5969]

Wife: "You did *_what_* to our bathroom!?" LOL

[@mattcantrell5640]

THAT WAS MY FIRST THOUGHT!!! LOL

[@kellymoses8566]

You can add sensors to detect CO2 and particulate levels to increase ventilation as needed.

[@arcrad]

It would be cool to see a scale model of a tight house and a leaky house. Scale model with an acrylic side. Have miniature ducting and HVAC. Then fog it and show how air moves differently through each.

[@atabetuatara]

This video convinced me Dave's system isn't enough; i.e.: a total of 130-280CFM across a 2k sf x 10f high ceilings will require (20k130 or 20k/280) 71-153mins to refresh. Instead, given the abundance of low cost high efficiency fans today (30W-50W non-induction, 150-250CFM 12inx12in at $50-80), I think I'll build mine with room specific recirculation and filtration systems so that areas that need faster air eviction (e.g.: bathrooms) can get it in a 2-5mins, whereas ones with more forgiveness can take longer.

[@joshuaolson5265]

I've always suggested that adding an ultra quiet fan duct should be right behind the toilet so it's pulling air with the shortest path to the toilet. Doesn't make sense to allow the stinky air to travel up to the ceiling and around the bathroom.

[@SJS_Family_Racing]

Yes. As an HVAC guy it’s a pain in the ass to control humdiity but I won’t say no to them buying a whole home dehumidifier and humidifier plus a ERV.

[@GLHerzberg]

3:12 Evidence: water drip stains reflecting light on the wall-paint above the picture. 6:21 Bedroom door was closed for the fogging test but is now open. Hmm... 6:40 Would manually boosting the ERV be a required practice anytime someone takes a shower? Hmm, really not fond of having yet another 'thing' to manage. So, is that in tandem with a bathroom exhaust or is boost-mode the substitute? 9:00 Bedroom door is ajar so not open but not closed either. All this critiquing aside, I admire the wall covering behind the vanity mirrors. That's nice!

[@kc9scott]

I have no personal experience, but I’ve heard that HRVs/ERVs can have an input of your bathroom exhast fan power, and automatically go into boost mode whenever someone puts the exhaust fan on.

[@nwsvndr]

Yes, the boost mode substitutes for the exhaust fan. In other words, rather than turn on an exhaust fan, you turn on boost mode. So it isn't "another thing to manage."

[@kc9scott]

@@nwsvndr That’s unfortunate. It’d be better to have a relatively conventional exhaust fan in the bathroom, where it feeds its air into the exhaust strem of the ERV. Or some other way of ONLY boosting the exhaust from the bathroom, not from the whole house.

[@MattSapp]

For your 2nd and 4th timestamps, I don't think you "caught" him in anything. As he explained at the beginning, there are 3 exhausts in the bathroom/closet and no supplies. The supply air has to come from somewhere - the bedroom supply being that location. We don't know how big of a gap is under the bathroom door, but in order for it to work, the supply air has to have a way to get into the bathroom.

[@Senthiuz]

​@kc9scott There are systems that will open an intake damper when rangehood or bath fan are running. The issue being an ERV doesn't have dampers for direct control and has limited CFM compared to a relatively massive exhaust fan.

[@Zorlig]

You need a control, where you turn the ERV off completely for the test.

[@BenBrand]

Exactly! The fog would naturally clear on its own, even without any ventilation

[@firemanj35]

Hey Matt and the fire service we use a thing called a positive pressure fan to help moose smoke or fresh air into the house and move smoke out you could do the same thing with a fogger outside pushing the fog in and pressurizing the house and it would leak out of any place that's leaking air

[@mikee9167]

The heat exchange between incoming and outgoing air is also a killer feature of ERV/HRV!

[@nativermonter802]

Matt, can you please provide the brand and model number for the finished/decorative vent covers you used? I've been trying to find a good set for my HRV vents for quite a few years now. Getting sick of looking PVC with unfinished drywall around them... Thank you!

[@thehobbyguy7089]

Are there more discrete looking registers for the Zehnder system?

[@xmas1888]

Would call out that the ERV is going to try to equalize the humidity between the inlet and outlet air. So all the humidity you’re dumping into the bathroom is going to be spread across all the outlets around your house. Essentially you’re humidifying the entire house instead of one room.

[@safwaanrafeek]

Seeing this, now id like to see a video of all your equipment and, devices, and gadgets throughout your house after you lived in it for a few years.

[@kirkwilson5905]

Oh and another issue is a fireplace. You need fresh air makeup for that as well. Some models have operable make up air vents and others don't (masonry). Even closed the flue and air dampers aren't going to be as tight as some are suggesting the house needs to be.

[@CWK09]

It would probably be more economical to have a faster extraction to the attic and just condition the attic space. Have a timer that turns on when the bathroom vent turns on that turns the attic conditioner/dehumidifier on for an hour or so. I do like the idea of air coming in pre-filtered, but unless it’s using something like water extraction it means you probably have to change the filter every month or so. Unless you have a walk in attic that’s not ideal.

[@Brane_Ded]

11:30 is there such a thing as a barometric sensor for your ERV? It could detect a negative pressure and put the erv in to boost+ mode to help reduce that negative pressure.

[@colinstu]

There are CO2 based fog machines that are a lot more pleasant to deal with. Not having to burn that jungle juice or whatever they call it.

[@greg925911]

So Mat i work around steel stud all day and the use the saw to cut them id if you vould use Rockwool sound proofing to see if it would soften the sound of the cutting in a built box to say for cutting those steel studs if Rockwool would quit it down

[@ahnilatedahnilated7703]

One thing I was worried about with your test. If you have 3 extraction vents and no way to get fresh air into the room with the bathroom door closed, what is the gap below the bathroom door? Will it accommodate all that CFM extraction? I noticed for the boost test you opened that door to the bathroom.

[@yowheeler]

Matt reads and remembers all our comments and thinks about them for years

[@Chris_In_Texas]

How does your ERV work with additional high extraction fan loads, like dryer, vent hood etc? Do you have supplemental air intakes etc for when they are running? Also I wouldn't use fog machine as most are oil based, I would use the "smoke" bombs that are used in some air testing. The smoke candles or smoke pellets can burn and generate 40,000 cubic feet within a few mins for HVAC testing. Great work. Do you have a in depth video specifically on the HVAC/ERV system you have? We are getting to the point where our ERV's should be replaced and I would like to look into options to pipe dedicated runs instead of the standard supply into the HVAC return air systems that we have now. 🤠👍 Any good companies in DFW?

[@1979royalknight]

Interesting hinge on you shower so you have a tilt glass panel (where do you get those type of hinges)?

[@TinkerTry]

Great video! I know I regret going with a less efficient ERV that uses my air handler ducting rather than a dedicated system like your Zehnder, which also means colder air in winter coming in, and less efficiency not helping. Lower speeds on 100% would have been far better.

[@kellymoses8566]

KZbin: "You can smell a fart in Matt's house a week later" Matt: "And I took that personally".

[@skapur]

A control test would be to turn of the fresh air system to see if the fog clears on it own without any air exchange

[@duanehundley]

Looking forward to the leaky house fog test

[@HiroSato-l7n]

I do have a question regarding the system itself. Since it is a tight house what would you expect happens as the system fails due to electrical issues? I would assume you would end up with a house that’s not regulating flow of air through the house at all. The question, would be then if the system had a malfunction what would happen to the air. Stangnate? Would you do the same test with the system off?

[@jamesrobinson1022]

There is alot more variables to test on this such as using stronger scents and doing it in the rooms that have the supplies and also checking surfaces for residual contamination. What does system do in the case of a fire? especially in a passive home where the fire needs oxygen but if the system shuts down then all the oxygen would be quickly used up putting occupants at risk of not having some breathable air but also needing to exhaust the smoke cause even the tiniest fires even if put out quickly do a lot damage with costly cleanup. Can system be separated in zones since certain parts need more or less supply / exhaust depending on what rooms are being used throughout.

[@MtnXfreeride]

If you shut the system off, does the fog natually disapate? A control would be cool since it is such a slow process.

[@dus10dnd]

Matt! Do you have a video about your bathroom? I am curious about your wall finishings. They look super durable and easy to clean. I think the way that we generally build bathrooms is really dumb and I am looking for all of the best things we can do. Like making the entire bathroom a pan, rather than just the shower... pretty easy to get a leak in a bathroom... I'd prefer to catch it than let it get to other places.

[@daviddunn7817]

Is that 240 CFM divided by however many inputs? If so that's not moving a lot of air per room. For $200 I have a 290 CFM Panasonic extraction vent in my bathroom that removes everything in just a couple minutes. It's on a humidity triggered (adjustable) wall switch. True that it's not recovering any energy but if it's only running for a couple minutes who cares? Seems a lot more practical than that setup.

[@StevenCrothers]

Matt, man, while this test was neat. I got bad news for you... those fog machines just filled all your air runs with sticky glycol based residue. You need to clean ALL those pipes out now, clean the fan, clean the unit. It's going to attract and stick dust and load up the fan. That's a not insignificant amount of damage you just caused long term :(

[@martiruda]

I forced the ventilation system guys to put the extraction pie right above the showers, best idea ever. Don't let them put them outside the shower, you will even not have to turn the booster on to get the moisture out.

[@andrealaphilippe5926]

So Matt, how about having Panasonic exhaust fans which some models can hit 150 cfm per fan on high and 100 on low with a passive fresh air grille somewhere in a central area of the house like pantry ceiling that is vented to the outside ? Wouldn’t that be 1/4 of the price of an ERV minus the filters which can be installed somewhere in that passive vent?

[@froggey5689]

Go shoot a video in Cambridge, MA or San Francisco, CA of a true life science/lab space building. They have the best air management systems. Work of art if you ask me.

[@DigitalBenny]

Given the building materials we use in USA, there is no such thing as "too tight" No matter how tightly they are sealed, they wouldn't compare to "actual hermetically sealed"

[@KylePhillips-ww2li]

Bullshit. Illiterate?

[@urchin11]

When your ERV is in boost mode, it goes from 70 or 130 to 240, an increase of 110 CFM. Since you have a 10-12 inlets so that is split around them, so individually each is only drawing about 7-13-24. Is there an ERV that boosts by single location only?

[@johnmoricone294]

What happens when you open your windows? I encapsulated my crawlspace and did something similar to my attic but there are still leaks and I'm not totally sealed.

[@mistertwo6113]

Matt! Start thinking up a Halloween video so you can use that new fogger!

[@ChrisMaveric]

Good stuff Matt... that said, I grew up with a Dad that just cracked the window when supply air was needed. A simple but effective solution to a stinky problem. 😅 Always enjoy and learn so much from your content...Thankyou

[@dreednlb]

8:40 "Nathan Taylor To you & Tim Hill - Just so y'all know, the inspector was smoking inside of the hou..."

[@tills12]

i recently moved into a new, air-tight home and while I do appreciate my CRV it pains me that all the nice conditioned air inside my home is slowly being replaced with outside air. In the winter (up here in Canada) that means I'm having to constantly run the HP to warm up the space and I assume in the summer it'll be the opposite.

[@cryptojlg630]

While doing efficiency upgrades to a 90’s era boarded in home with tar paper (no HRV), I couldn’t find anything with as quick of an ROI and as impactful on the utility bill than a Ground Mounted Pergola Solar system. I couldn’t have triple glazed the windows alone in my home for the price and I generate 14,000 kw/h a year, in Canada. You can add insulation to the exterior, buy the most efficient windows out there, mechanically bring in air to it, and rebuild as tight of a structure as you want. But when the kids are leaving the patio door open, what’s really getting accomplished? You’re better off just making your own electricity at that point.

[@ronblack7870]

so does your system have a heat exchanger built into it? you did not even mention it just saying it brings in fresh and exhausts stale air.

[@joshualynn9913]

20 year hvacr tech working in a high humidity peninsula i question energy efficiency if we need to install an erv and dehumidifier (each consuming energy) but I'm no engineer

[@FelixRusu]

@buildshow Matt, I wonder what are your thoughts on how this system works when you have other air leakage sources like kitchen hoods with external exhaust & makeup air, wood burning fireplace with fresh air intake & chimney exhaust stack, dryer exhaust, etc - all not very well dampened with the OEM ducting & some relying on external registers with "flaps" that "close by gravity" when air is not blowing through.

[@sabregunner1]

i think the thing that people are missing is that with a fresh air system the house does "breathe" its just very controlled. i think people are just so used to the old methods of opening a door or window and creating a cross ventilation.

[@bille.334]

Our building department will not CO a house without a blower door test. The test can be no more than 7 ACH and no less than 3 ACH. If it is less than 3ACH, they will require mechanical ventilation. anything over a 400cfm fan will require some sort of mechanical make up air.

[@bhbaker220]

Ok. The real test is to see what your utility bill looks like. Please share and then try to compare it to some other less efficient houses that have higher blower door tests. Also interested to see a blower door test 1 and 2 years later to see if there’s an impact from warped doors.

[@munkydotorg]

What about in scenarios of power outages, particularly longer ones, especially during times of extreme weather when opening windows and doors is not an option? My biggest concern around houses this tight is when systems fail, or major outages occur. Thinking back to hurricane helene, if the house survived most unscathed, but power was out, a solar backup could have been damaged, natural gas may not be available for a standby generator. How is that factored in, or is it? With an older, “breathier” home, you could experience a long term outage a bit safer. I’m a fan of the tightness and the energy efficiency and comfort that comes with it, but concerns come when we are forced into these scenarios

[@rykdheiner]

Set up a fog machine outside of the house near typical leaky point and turn bath fans and maybe the hood range on something that doesn’t have a makeup air system

[@keiboman]

What's the ROI on everything it took to get your house that tight plus the mechanical ventilation?

[@sergeyb8]

It's all good but what's the limit on those flex hose runs? Last I remember checking it was pretty limited

[@jexl1059]

the other issue i have with ducts is dust in the ducts. is there a way to put places to open them so i can vacuum them clean? if i can do that im sold.

[@cujo7240]

A typical blower door minimum spec is less than 3 air exchanges per hour. At what value would you say an ERV is absolutely needed? Two builders here, Western NY, say they typically don't install ERV systems, and they tell me it's not necessary.

[@jezza6575]

Now the wife is going to expect a fart extract button in our bathroom…thanks Matt!😅

[@laloajuria4678]

ok your master on the first floor facing the street is a travesty...........who does this?!

[@milesscruggs2542]

What would be cool is if you can be a bit more scientific. Run a separate test over a two hour period showing what it looks like with the ERV. Seems unlikely that the smoke molecules would stay suspended in the air indefinitely so you would expect the air to clear all on its own. I’m a full believer in fresh air systems and sealing the house but this video actually surprised me by how little air was moved in that room. I’d say my faith fell a bit after watching this. Now I’m wondering if we need fresh air systems with zoning.

[@phillipcoiner4232]

You spent more on your ERV than I did on my HVAC [:o) I did get a whole house electrostatic filter. The air is the freshest I've ever experienced.

[@rosscoep1450]

What stops smells from the outside coming in through the fresh air system? Context - with certain wind directions we can smell smoke from the nearby "jerky" factory and the neighbors cows.

[@razaman514]

@buildshow Matt, do you monitor CO2 levels in your house? If so, what level does your air exchange system keep?

[@grand04gt]

I am kinda shocked that at your house and your level of OCD that you have not painted your air registers on your wood ceiling yet and left them white. I would go crazy if it were at my place......and i LOVE the ceiling!!!!

[@anthonyenosis1]

not to mention backdrafting furnaces if people improperly have a furnace and their exhaust venting fighting eachother

[@jylfarm1964]

Anyway, you don't want an extractor in the shower close to people because the shower will fell much colder. One of my customers have that as problem, the extractor just over her head and I did have to move it.

[@tylerbritt8645]

I’m in the process of building my house now and I want to make sure it’s done right since not many people building high efficiency homes in my area. Would a fresh air system and a dehumidifier take care of the issues people claim come with a tight house? In my area people say that a tight house will be eaten up with mold and rot in a pile in a year because of it not being able to breath.

[@danielchin8073]

In part, yes. Building tight and controlling how air flows into and out of a building and keeping all HVAC ducting and air handling inside the conditioned space will go a long way. ERV and dehumidification will help keep the airborne moisture under mold growing levels too. But you also need to make sure anything that can possibly see water can both drain and dry.