Thank you for all of the great and informative videos on your channel about ventilation. I've leaned a lot and am very excited to implement many of the systems you teach about if I ever get to build my dream forever home. One question (somewhat unrelated) I have that I haven't been able to find a good answer to yet is what happens when you have a very airtight house with all of these sophisticated, powered ventilation systems and the power goes out for hours (or even days) on end and they can't run? I'm from Texas and when we went thru "snowmaggedon" a couple of years ago, we didn't have power for 4 days, and even if we'd had backup batteries or a generator, it would not have been enough to outlast the weather. Of course, our current house is not super airtight so it wasn't a big deal (except for losing all of our heat), but I've wondered if in a new airtight house we need to design in passive ventilation in case of emergencies like that, and what the design might look like. Do you know of any videos that talk about topics like this?
Awesome video. Very well done. Love the Panasonic rep. 😁 Hope you and your family are well. Sorry I missed last Thursday, didn’t see the email until later that evening otherwise I would have been there with my tech issues and all😉 Grace and Peace Slick
Other than a home that is too tight to exfiltrate, I still think a ventilating dehu is the most pragmatic ventilation solution. You don’t necessarily need an ERV with a ventg dehu but you will most definitely need a dehu with an ERV in green grass climates. The argument at 10:22 that you can diminish the High demand on a dehu with an ERV to save money doesn’t work when you apply dollars to it. A full house ERV installation with 4 duct systems vs the little bit of energy you would pay with a dehu is a no brainer. Thank you Corbett for mentioning that a house should be tight enough for an ERV. A lot of people are out here assuming they need one when their home is slightly tighter than average and they’re missing the dehu strategy.
it depends. how humid is your area, how much air leakage is there and how high are the power prices? here on the other side of the world power prices are high and latest news is predicting it to double. then running costs really come into play. but also we are really talking about places that would be running an HRV anyway. if your going to run a dehumidifier you might as well swap the core for an ERV.
To clarify the last point of the supply air from the erv you want to put a dehumidifier. Also pur house is 560 sqft. What dehumidifier is recommended. We are also off grid and only make our power from our solar array so amperage is important
What people don't understand is the ducting length and air flow in air tight houses. And how much volume is actually going through it and from where at. Then add on forced air heating and the hrv. We found radiant heat to work better with hrv and ervs in air tight houses.
ALDES makes the best erv whole house bath vent solution it pairs an erv with multiple ZRT or ZRT-2 to replace each vent fan in the house. It can boost 1 bathroom without increasing cfm in the others.
If you don't need an ERV, you can do the same basic job with regular bath fans and an AirCycler. Check this out: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-bfd69xRbQxM.html
Thanks, this is a great video. If we don't do the CERV we're in Southern Vermont.... ERV or HRV? It seems they are good for colder climates now but where is the line?
Hey Corbett, love the video and the info! Can you confirm what the air tightness threshold is where you would need an ERV vs a simple outdoor air makeup system? Is it when you get below 1 ACH50?
It depends, but about 2 ach50 we start getting generally concerned. This vid for further detail: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-lnOCAPPVT5g.html
So I'm exhausting air from my bathroom to get rid of excessive humidity in my house. So the companies making more money selling ERVs say I should use an ERV to do this. This I understand. However, since the ERV will keep some of this excessive humidity in my house, depending on climate possibly useful for cold months. However I think not, universally useful. Use an ERV for constant fresh air is usually good, even put exhaust vents in the bath. However when the shower is running an exhaust above or next to the shower going through an HRV or just out the wall in warm wet climates is better for total energy load and humidity balancing. Dehumidifiers would also be in my home (unless I lived in a dry climate) and lots of houseplants, picked from the ones NASA found cleans the air, plus herbs in the kitchen window. Because they help with mental space conditioning.
The only thing I struggle to get over is the privacy that a bathroom fan brings to a bathroom in the form of noise pollution. I assume that an ERV system venting from a bathroom is extremely quiet compared to the hum of a bathroom fan. I am building a house and would love to go tight + ERV but this is the last hump I am facing. Any ideas to improve the "privacy" factor of a pretty quit powder room? Insulate the heck out of it?
In Japan where paper thin walls are common they use white noise machines that are triggered by operating the lights or even by PIR sensor. Sometimes they use waterfall sounds, but that seems to me like it just adds to the problem!
Unrelated to the this video, but was curious, have you done a video about insulation gaps in walls or ceilings affecting sound quality? Specifically, I have plans for rafters that are layered with external insulated panels and am concerned that if I do not add something in the cavity that this will exacerbate reverberations within the room [ Some rooms will have finished rafters as ceiling. ] Also, [ since I am fully encapsulating the exterior of the house with insulation ] the same question applies to the ceilings in the house. Should I add something behind the drywall to aid in damping sound transfer? Thanks for all the amazing information provided in your videos and show. Always enjoy learning something new from you.
I don't think he's a video on that specifically, but I'm not sure. This crosses into what I do for a living so I'll answer a little right here. For sound reduction through a wall, you generally want a few things: air tightness (think of how little you have to open a window to hear through it really well), materials of dissimilar density (so they can't resonate or transfer the same frequencies easily) and limp mass (to convert sound vibration to heat). Air gaps help reduce the transfer of sound through walls by disallowing one side to conduct sound to the other side, but it's just one part of a lager strategy. Frankly, if you're already building air tight, using mineral wool insulation and stopping thermal bridging, you're already going to have pretty good results, even if there's more you can do if you want to attain some specific STC. With the exception of closed cell foam, what works well for thermal insulation tends to be acoustically insulative. There's more to it of course, but that's a good starting point for thinking about it. If you're really serious about your house's acoustic performance, you should probably hire an acoustic consultant to look at your plans and make recommendations, even if you won't have them do the implementation.
Managing heat loss is one of the main reasons why an ERV exists - and it manages it very well. Look for some other videos on this channel that explain how it works.
This is your BEST video yet! (which is saying a lot, because yours are the best on RU-vid!) This answered all my questions, especially the ones I didn’t know to ask.
Great video! Amazing to have all the reps jump on like that. I noticed a few mentioned the kitchen. Are there any recovery ventilators that are rated for use with a range hood? I asked Fantech if their light commercial HRV (higher CFM and plastic washable core + washable filter) could be used with their hood liner as a dedicated kitchen exhaust/makeup air solution to avoid using a heating coil on makeup air in a cold climate. For a net zero house, that coil means a major strain/expense on solar power. Unfortunately, use in that manner would void the warranty, even with an additional accessory filter box installed in front of the unit.
Great video. Excellent comment near the end to place the ERV before the dehumidifier. This will normalize the air temperature before it enters the dehumidifier.
Have you considered a video on "what to do/when to run" an H/ERV when outdoor air quality is bad. Like with wild fire smoke that seems to get worse every summer? I love your videos.
From a ducting perspective, How can I tie in my kitchen and bathroom to my ERV system. This is for a 1 modest bedroom cabin. What ERV(s) would you recommend?
Hearing the description of these system's membranes and all I can think about is PFAS. Are any of these systems PFAS free? I mean I love the PFAS in my blood, my food packaging, my tap water, the rain in Antarctica, my carpets, my cookware, my flame retardant clothing and furniture, my water and stain resistant fabrics as much as the next guy....
Long time follower and student. (Just a homeowner) My Engineer has spec'd FanTech HRV Hero 200H units in my shower/steam room. I didnt want the typical ugly Panasonic Whisper fans with lights. I wanted a cleaner look. I had suggested the Fantech Multi Port CVS400A. But he went with the HRV. I had never heard of using an HRV so I called fanTech. The Tech at Fantech advised against using the HRV in that fashion. So I am thoroghly confused. The HRV is part of a fairly significant overall engineered system for a my new build home in Hoonah Aalska?
At 8:50 Ken of Panasonic says the ERV core passes moisture both ways, unlike Gore-Tex which only goes one way. In my climate I can't conceive of a time when I'd want moisture bringing in from outdoors so I'd want a Gore-Tex style core. This would reduce humidity of incoming air if its more humid than the outgoing but it wouldn't increase the humidity of incoming air if the outgoing was humid. Sound perfect! What have I missed? Great Video, thanks.
I really like how you did this video. A lot of great information. My house is 100 years old, and I was thinking about doing this, but the placement of the ERV would be in the attic, outside of the envelope of the house. They house isn't well insulated either. I think I could still do a whole-house unit, which would be awesome. I still need more information, so I'm off to learn more...
I’m with you a v. According to RedCalc and Cores from Renewaire, the payback for an ERV v balanced ventilation using AirCycler is well beyond 25 years in my climate.
Don’t do it gor payback, do it for pressures. Borderline of Balanced Ventilation: When Bath Fans Won't Work, and an ERV Becomes Necessary at Home ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-lnOCAPPVT5g.html
Thank you Paul! Kitchen cooktops I think is the only reasonable pollution source existing in most homes that uou would not want to draw thru an ERV core.
Thanks for your information, I have a one story house with a encapsulated ,air sealed crawlspace, with an attic that it has been air sealed and insulated. My question is, can I determine from my Airthing’s monitor (high co2 , 2 people, 1800 sq ft)that my house is so tight it could benefit from an ERV. Living in Augusta, Georgia
I have a 1980s leaky house, and one person in a bedroom for a couple of hours will make the CO2 move into a less desirable range. I changed my HVAC system to continuous ventilation, which runs the fan several times per hour, and that was better, but not enough. Then, my monitor developed an interface with my thermostat, and ran it enough to keep CO2 in a "good" range of under 600ppm. This is still not ventilating with outside air, just using other leaking air in the other bedrooms to dilute the CO2, as well as some possible air leaks in the HVAC system. With your better sealed house, I think you will need more outside air to dilute CO2 in your home.
Thanks for your reply, my house was also a 1980s leaky home. Now it is basically as non-leaky as I care to make it. I have no gas appliances within the envelope and a non-venting clothes dryer. Sealed ductwork, a dehumidifier for the crawlspace, and one for the house ducted into the Supply side. I purchased my air monitor before I started any of the work so it showed the changes. I also installed remote bathroom fans with speed control and now use one of them on a Lutron Casita switch that I programmed to come on intermittently through the night to dilute CO2 in the Bedroom, this works pretty good but increased dust from pulling it through the walls and wherever and has let me to the desire to put some fan powered slightly positive pressure filtered air into the bedroom space wired in series with the fan that runs intermittently through the night. Hopefully eliminating its need to pull it through the walls. I guess I just didn’t see the need to do a blower door test knowing I wasn’t going to seal the house anymore and that all I cared about was the CO2 reading and clean air. Mr. Lunsford doesn’t complain about any condensation issues in his crawlspace from his make up air unit, and if it doesn’t work for me, I won’t complain about it either.
First of all thank you for such an amazing content!!! I am am building new ICF home in South Florida where humidity is very high. It feels like the system should be comprised of: - stand-alone whole-house dehumidifier - multi-zone properly sized AC - high performance ERV with boost mode, continually pulling air from bathrooms/kitchen and supplying fresh air to bedrooms and living room - no (!) exhaust fans - it takes some faith to say that Do you guys agree?
You still need dedicated exhaust fans in bathrooms, kitchens, garages and basements (and other places where airflow would be poor). You only use these dedicated exhausts when you use the rooms like taking a shower, cooking, woodworking in the garage or basement, etc.
@@HomePerformance Yeah, this video explains you do not. But I find it more practical to have dedicated exhausts in these areas just in case something happens like the ERV failing or whatnot.
Thanks for this video and your many others on the topic. I’m building a new, tight home and installing a Zendher ERV. I’ve emailed this question about bath fans to my Zendher sales rep who says things like, “you shouldn’t need a bath fan….” I wasn’t planning to install fans, but then my hvac contractor tells me that he has often had to go put them in after the fact in similar homes. He works on a lot of “high-end” homes that are tight and have ERVs. He’s not insisting that I put in a fan, but he’s pretty firmly advising me to do it. Says everyone is having come back to put one in later and it makes a mess and costs a lot. I really don’t want a fan, but I also am worried about mold and humidity.
If you put the ERV exhaust in the right place, never turn it off, and maintain the system, you WILL NOT need any extra ventilation. And bath fans do harm very tight homes.
@@HomePerformance thanks. Can you tell me about the “right place”? We’re following the spec sent by Zendher. We’re using wall mounted, 2 exhaust tubes in each bathroom.
hey, very informative as always. My question is when using an erv for bathroom extraction, is it assumed that the bathroom is actively heated beyond the addition of steam to the room? Is main the purpose of the erv to extract moist air or to recover heat energy? It seems a lot of the time that this is skirted around. I am genuinely unclear on this when they are used outside of a Passive Home environment. They seem to be an expensive bathroom extraction fan if humidity control is the main purpose. I am really wanting to understand the purpose in homes that are not in the Passive category.
Here’s the explanation, GingerZNZ: Borderline of Balanced Ventilation: When Bath Fans Won't Work, and an ERV Becomes Necessary at Home ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-lnOCAPPVT5g.html
@@HomePerformance Thanks, your info is great, I guess my question is, what is the purpose of an ERV in a new build non-passive dwelling? 1) Energy conservation 2) Humidity/Condensation Control 3) Balancing Air Exchange 4) Extraction 5) Convenience in having a single unit doing multiple operations. 6) All of the above 7) None of the above I'm not trolling, just trying to fully understand when they are best used vs individual systems managing supply and extraction. In NZ there is a GreenStar standard that requires an MVHR to be installed to comply but with no reference to the purpose or specs of the machine. here is the assumption - by recovering already consumed heat energy it is more environmentally friendly, yet my calculations on energy consumption vs cost & running cost vs alternatives don't show a positive outcome in an energy reduction capacity or increased utility over using smart sensor on-demand ventilation and extraction. I often get the "Emperor has not clothes" vibe or Am I missing the point? Should an ERV be regarded as an air quality product or an energy conservation product?
fine from a building science perspective, but my clients occasionally object to the sorption of odors kn the erv core from the bathroom to the rest of the house. not a deal breaker, but something i bring up when the spec and design for bathroom extraction arises
There is no transfer of odors. The makers have been known to state they will confidently lick the incoming side of the membrane to prove the point (I won’t say which ones told me this).
@@HomePerformance nevertheless, for one of the manufacturers represented here, there is (or was in my projects). I'll admit that I don't know if it was sorption or leakage, but I can confirm that they could smell their bathroom all over the house.
What I took from the Panasonic Rep; was you can only put the their ERV inside a home that has entire conditioned attic or crawl space. That eliminates a lot of build types.
well he was the only one who addressed that point. i think the others would agree for the reason he used. i guess you would have to ask the rep that question for each brand
Broan - Nutone has a cavate. Hmm. I did ask this of you, when you built your house and I am planning to exhaust our bathrooms with an ERV. My concern was the core. In Zone 1, the ERV is already brining in moisture laden air and from what I understand, the crossover of dryer air that is exhausted, actually assists in drying the incoming air, in the crossover core. Your comment?
@@HomePerformance Panasonic at 8:16 began to explain the issues with the temperature at the mass and he clearly states, seconds later that if you put the ERV outside of the conditioned space - you will start to have issues. That tells me, the use of an ERV is limited its use, only to buildings that are tight and condition to the under side of the roof deck. That leaves out a lot of vented attic homes that you cant place an ERV in.
@@davidbruce5377 thats why you have a whole house dehumidifier. if you have wet air going out, it will cross over to the inlet side and go back into the house. keep in mind efficiencies, they are not perfect (local one here is 80% when at full speed) so its still going to push some moisture from the shower outside. the rest is dealt with by the dehumidifier. that might sound bad, but as there is very little moisture coming in from outside, its not much moisture for the dehumidifier to deal with. the bit about having the erv outside conditioned space is down to how cold the weather is. in warmer places its not much of an issue.
@@tweake7175 Good response, but its not so easy if you are thinking of putting the both together. Its a pressure nightmare. Here is a n email from a Santa Fe Dehumidifiers rep; "The dehumidifier still has to work regularly like it normally would. Regardless if ERV supply is going into the Dehu, or dehu supply is going into ERV, the air volume/power/speed needs to be as close to each other as possible. For example, for our 70 pint, cfm rating is 150. If the intake/return air is coming into the unit, and it’s not 150 cfm, it’s going to reduce the performance of the dehumidifier because it’s not using the proper amount of air. If the amount coming into dehu is more than 150, there is too much air, and not all air is going to be dehumidified, it is over capacity for what the unit can handle, force feeding more air than it can handle. The same holds true for the ERV, it’s not catastrophic either if it’s not enough air, it just mathematically reduces the capacity of the unit. Again in this case, too much air overwhelms the ERV if not equipped for 150 cfm. With all that being said, we also don’t want to recommend the UA 70 be used for just fresh air intake, as it won’t dehumidify enough with just one air pass through dehu. We would want to make sure that the dehu Is in fact getting return air from house."
My old house is way too loose to need an ERV, but I am interested in all these technologies. One thing that I thought was a little dubious was this claim from several manufacturers (and implied from all of them) that a continuously running ERV would be sufficient to exhaust air from a bathroom and mitigate the typical humidity issues. I have a small bathroom, appx 10x8x8, and it had an exhaust fan of appx 75 CFM. It was woefully inadequate even if the fan was turned on immediately before any steam from a conventional shower was created. You would still get heavy steam bleeding out of the bathroom, a fully fogged window and mirror, etc. I upgraded to a 110 CFM fan and it's better, but it still gets momentarily overwhelmed and can take 20 minutes to clear out the moisture to a manageable level where it's not condensing and bleeding into the hall. So, the idea that some continuously running ERV could handle that task with, say, 40 or 50 CFM is laughable. Would to clear it out? Yeah. Eventually. Like 4 hours later. . .
You should test your bath fan. I bet money it’s not sucking what the label says, and fyi I have this exact type of system in my home and it works beautifully.
@@HomePerformanceI"ll take your word for it, but it does stretch credulity. I replaced the junk Broans (noisy 2000-era) with Panasonics, and I believe they do get some outside certification on the CFM. They certainly move a lot of air. Is it really 110? I don't know. Is it only 50? I doubt it. But seriously, you're saying you can have somebody take a hot shower and 50 CFM keeps it clear?
@dmorga1 I’m saying 25 cfm is enough if your bathroom isn’t wacky. Code only requires 20. Continuous is completely different than a fan on a switch, but feel free to disbelieve it if it makes you feel better.
@@HomePerformancecan you do a video specifically on why ERV in a non air tight home is a bad idea, why is having windows open in bedrooms a better solution then using ERV’s, because thats the alternative. I keep seeing you gloss over this without adding context in many videos.
If your fresh air system uses fans and filters, the operating cost would be the same. The difference would only be the cost of the unit minus the additional energy load your dehumidifier will need to make up for while you pull all that humid air directly in without pulling moisture from it first. I’d argue home comfort will be much better with an ERV since you’ll not be relying on a separate dehumidifier in a fixed location, the ERV will remove some moisture and distribute. You will also need bath fans to locally remove moisture from bathrooms. The more I think about it the more an ERV makes sense.
