Great video and completely understood. Would like to see a second part on this of sizing and location of supply air coming in at the best locations to assure operable balancing. Sizing of lines, suggestions on proper vent grills or manual open closed vents.
16 yr HVAC service technician here. It’s infuriating to find out that my common sense has been correct from day one about vent locations and the need for ervs. I’ve always wondered why the ‘fart fan’ is always located closest to the toilet rather than just over the shower. Dumb! It’s not for odors, it’s for humidity removal. Period. Great video.
@@HomePerformance Wouldn't ducting into the return throw a lot of new , moist air (from the outside) into the unit, vs into the supply and letting it get comingled with other, already dehumidifier air and then sucked back through the normal returns?
@@HomePerformanceisn’t it a bit more nuanced, exactly the way you discussed flow through the bathroom, you’ll want to ensure that all the living spaces have good air flow? I’m referring to dedicated supplies.
We didn't think the efficiency in the Atlanta area would justify an erv. We have that exact pattern for exhaust. Only difference is we use fresh air intake on our dehumidifier and exhaust using a central bath fan ducted to closets and bathrooms. We set both fan side of the dehumidifier and the central exhaust on the same controller. As one goes up the other goes up. We have it set about 25 cfm higher intake then what the exhaust is set.
Thoughts on sensors to control ventilation? I like the idea of controlling the ERV with a combo of indoor and outdoor IAQ sensors, both to save money by not needlessly over ventilating and to shut down the system during events like wildfires or dust storms.
Great video and channel! I found this channel after Corbett's recent appearance on Mat Risinger's Build Show. Catching up on all of the great videos here now!
Thanks for your channel. I'm actually doing a major rebuild on a semi-remote island near Vancouver. It's about as airtight as possible with a rebuild, with hydronic heating, and will require all sorts of creative installation to get the lines where they need to get in a building not designed for HRV/ERV. I am relying on your channel, as getting anyone out here to do the work is impossible, so I'll have to become an HRV expert pretty quickly. 🙂
Having 130 continuous, and a 160 ERV is not enough headroom for a party or any real change in CFM. Also, running that close to capacity will be louder, and potentially using more energy than running a 300 CFM machine at 130, while having meaningful extra for emergencies. Provided that the unit has nice control range and not unreasonable pricing for that additional capacity. I ran a 360 at 150, which is unnoticable 24/7(~30W), but has plenty of umpf for when I need a boost (almost 150W).
I happen to know from experience it is enough, I’ve lived with ERVs for seven years in two homes. What 360 are you referring to? That’s not a residential sized unit. Also, what emergencies are you imagining?
Great video. However, I don't actually see placement of the supply grilles covered in the video (as title suggests). Lots of detail on unique CFMs per exhaust, but where did you place your supplies and at what CFMs? Possibly you can just post an image of the floor plan with supplies and exhausts. Cheers.
Yeah, I was wondering if I'd missed the supply side but its not there. Also, I've got a 'shower dome' which is awesome & keeps nearly all of the humidity inside the shower cubicle. I haven't seen any ERV/HVAC people discussing how this changes things.
In the US, we size our ventilation off numbers for exhaust, then fit the supply to that (as long as ASHRAE 62.2 does not exceed, in which case use bigger target). In Europe and even Canada, it’s opposite- they size based on supply targets and fit exh to it. I do mention, but easiest (and best imo) is to inject fresh air to return of central HVAC ductwork. Otherwise just make each room either supplied or exhausted as far from the door as is feasible.
Looking for some clarification. Really like the idea of an ERV replacing the bathroom exhaust fans but getting mixed feedback when I talk to professionals in my area. The ME who designed my system says here in eastern NC we can’t do that. The installers in the area say the ERV can supplement but not replace the standard bathroom exhaust. Broan’s website advises against ERVs exhausting humid air. But this video and a high performance video says we can. Any insights you can offer? Thanks for information and the channel. Really appreciate it.
@@HomePerformance it is where I am. Multiple code officials in my county and hvac pros stated definitely bath exhaust must be directly vented outside. ERV was specifically not allowed.
Wow! I have watched this 3 times! I’m in the Eastern-most city in the US (Eastport ME) and am having to figure this all out on my own! I have spent days researching and now are not going to do spot units. This is such a head jam for a novice (to talk positively about myself)! Anyone know of a contractor in Washington County or NB Canada? That’s where my search went last night! I’m putting in 3 single ductless Mitsubishi units and full envelope closed cell insulation. I love my people but they know less than me at this point. 😢 I am subbing out all my work (I’m the Gen Contr😅) and have learned so so much but this keeps me up at night!
You are not alone my friend- many of our viewers and clients are the most savvy people in their entire town. Like you, they all have to push their builders and subcontractors to do new and better things. Thanks very much for watching, happy we're helping you with your project. Try these resources: homediagnosis.tv/pro maineindoorair.org/member-directory/ Best of luck!
Thanks for the video. In the future I will add a CERV2 or other ERV due to cost, but what I've been trying to figure out is exhaust. My thought is that I could use my bath fan holes (4" ducts with backdraft damper flaps) since they are already there for exhaust. I also have a return in the kitchen/great room for my whole house dehumidifier I could use to exhaust the kitchen. Those are already there. Currently, I have a Sante fe ultra 70 with 8" fresh air and 10" return that goes into a tempering box which then enters the dehumidifier and then enters the return on my air handler. Fresh air intake, return, and my air handler all use their own merv 16 filters. It is all a retrofit except the A/C and I'm looking at how to make improvements later. I've been using air quality monitors to measure C02 where we sleep and VOC's to dial in my amount of fresh air coming in which I do by opening or closing the amount of return air. The dehum fan I run 24/7 and my ecobee calls for dehum when needed. So, anyway, any suggestions with setting up whole home dehumidifiers and adding an ERV later would be cool. Also, I recommend looking at the CERV2 from Build Equinox if you haven't. Expensive, but it is awesome! Unfortunately, the company my builder used greatly oversized my air conditioner. I'm using dehum mode on it and I've lowered the fan speed since I literally never need stage 2 to get more run time and dehum. It's fun to sort out, but maybe you can talk about ideas for retrofits like in our situation. Take care keep up the great videos!!!
I love the Cerv2 we put into our office and I'll be ordering another for my house and I'm in a similar boat to what you've said above. The only thing, if I may, I would consider adding would be a zone damper and put your bathrooms on that zone and then you have a second zone with everything else. What you've described is what I originally planned, but after using the Cerv2 unit at our office now for a prolonged time, I would definitely only want the bathrooms to be pulled from if the unit wasn't in recirc mode. This thing is super smart and does an amazing job... I'm adding the outdoor sensor actively as there is one event happening every day at a certain time that seemingly is coming from outside the building... Someone I never would have known or paid attention to. I love the Cerv2 and will be coupling it with a heat pump unit at some point in my setup that will cover the majority of the load. In any case, I am not being critical at all of what you said, but this is something I had to adjust after using the Cerv unit for a while so I thought I'd share my speed bump. Edit: I thought I would mention/remind that the system you always hear people talk about generally has the replaceable core vs our much more programmable heat pump system. So we don't have anything to replace, but our air streams work differently .. that's the reason I mention the above and the video goes against what I said... The core exchanges much of that energy and exhausts the rest... Ours very well might be simply recirculating depending on the outside air variables.
One thing I noted from your current setup is that your dehumidifier supply puts its dry air into your HVAC return. This isnt ideal since you've removed your A/C's opportunity to dehumidify. Also, I think you mentioned your dehumidifier is always on. This will push air over your cool/wet a/c coils drying them thus pushing water back into your home. I found it counterintuitive but it's fine to add a little more static pressure to your supply (in most cases). Hope this helps
@@DonovanSexton so some sneaky dude is taking a stinky dump every day and it's smelling up the house? Or are they smoking up outside? Sorry I couldn't tell. CERV2 is so cool. Tye is the man. Maybe zone dampers are the way to go.
@@DarenSpinelle Not exactly. The evap coil will be removing less latent heat (moisture) from the drier air so an added benefit is that the a/c can be down size due to a smaller total cooling load.
Really love your video topics and the vast amount of information they provide. Would be great if you can do something about building a pretty good air tight house with a fireplace or wood stove or both. Is this possible to achieve. Thanks
Thursday’s video will hit home for you, Robert- but short answer is that will not work in many cases. Depressurization sensitivity is the issue once you get airtight enough.
My contractor and electrician were incredulous when I insisted that the exhaust fan/lights be put in the shower, but I showed them that it was rated for it, so they did it. Keeps the mirrors dry!
You have mentioned a few times on the comments that there shouldn’t be a ERV exhaust in kitchen. Can you provide an explanation why!? Or maybe you already have a video where you explain this!? Thank you.
There should be a powerful exhaust fan over the cooktop, dumping outside. If you have that, whether or not there’s a 25 or 40 cfm ERV exhaust in the space is not a big deal.
@@HomePerformance So you are not against having an ERV exhaust in the kitchen!? It’s just if you have proper exhaust over the range with a proper makeup air system there is no need for it!
Okay. But, what would you do if you want to be able to have the steam/humidity stay in the bathroom for a bit? My wife has super curly hair, and it helps when she is styling it. I like to take baths and keep the fan off so the air is more humid and warm. Can you control that somehow without messing up the rest of the system?
In a well-designed home with the right equipment installed, you’re able to do things like this without big consequences, as long as you know how to make the system work for you.
Sir, this is a design decision, if you want a steam room to double as a restroom, then so be it. It’s your castle. I think you are asking the right questions. And remember, controls are a key to automation. So that closable damper can be on a sensor. Just sayin. Keep a healthy distance from zealots. They smell funny.
4:04 - - vent is best in corner over tub (it grabs as much steam a possible) 🙂 4:39 - - vent is best in corner over shower (vanity mirror will never fog up) 😊 4:50 - - mistake to put vent in middle of bathroom (less efficient/effective) 😶🌫
You have nearly half your total exhaust in the bedroom / ensuite and none in the kitchen. It seams that cooking odors would tend to migrate into the bedroom.
I’m assuming the kitchen would have a separate exhaust with high cfm and separate make up air system. But you make a good point. Given the proximity lingering odors and other vocs when not cooking would naturally be pulled into the master. I wish Corbett would address this.
Bedrooms are positive pressure zones, bathrooms neg pressure. When cooking, the kitchen becomes neg pressure zone because of the massive exhaust hood with dedicated make up air (400 cfm, 2.7 times more powerful than the ERV).
The intention with all ventilation strategies is to dilute the breathable air, not scrub it. ERVs are generally designed for Class 1 air. FYI - It would be best to post a comment of this nature in a form of a question. That way you don’t sound like a neophyte. Cheers!
@@HomePerformancewouldn't it be more efficient and effective if you run the air from the kitchen exhaust hood through a whole house dehumidifier, which takes the fresh air from the inlet of the ERV/HRV equipment? That way you are keeping the building envelope closed.
I have a question regarding the ERV exhaust intakes for closets. I was taught that HVAC returns are discouraged even in walk-in closets as that accumulates dust in the closet contents. Would ERV exhaust intakes create a similar issue despite the lower CFM flow relative to an HVAC return? Not that I would have to worry about that since code required HVAC supplies to walk-in closets which have exterior walls in my newly built house. That bit of code adherence was ironic given the mythical Manual J/S submitted for my house.
Great video. So if you exhaust from some rooms and supply others, the air would need to make its way through the loop. What if the house has minisplits in every room, or say VRF/multisplit type aircon with the only ducted system being the ERV? Would that still be enough or would there be a need to exhaust/supply every room?
splits will condition the air and remove some moisture however you still need to exchange the air otherwise co2 will build up and other pollutants. With a good temperature exchanger in the HRV/ERV, the temperature of the conditioned air should be retained to a large extent.
@@bevthebuilder5457 “Should be” is a statement of hope. That’s not how physics works. Assuming a variable capacity system can “control” the temperature and heat energy in the air is a fundamental misunderstanding of Psychrometrics. Furthermore, it’s all about a given manufacturer’s testing and performance capacity tables being available for scrutiny and after installation commissioning. If you can’t predict it, why do it.
Great Video! Quick question with regard to this topic. How do you factor in a large vent hood over the cooking range? Some of those are around 1200cfm. Do you offset for these temporary draws?
Depends on air tightness. It’s not an issue in a leaky home. Tighten things up and mostly your options are: add dedicated passive makeup air on a pressure switch, buy a heat pump dryer (best option for energy), or find another way to get air inside. For instance, Lunos ductless HRV fans allow about 35 cfm each as a passive makeup air mode. The fan turns off when it senses the pressure difference (I called the US rep, 475, to find out). That’s 140 cfm with four fans, about enough for a dryer. I have seen reports of new ducted HRVs that will ramp up exhaust when they sense a makeup air demand.
FYI, Connor, the Lunos isn’t one of my recs because it doesn’t set up a consistent pressure imbalance. So you’d still have to use bath fans, which in airtight homes is a nono.
Disagree on the tiny thing- it holds 17 lb wet I think- efficiency of form helps. Also, the Miele washer it pairs with spins faster than any other residential dryer, so the clothes start drier to begin with.
@Home Performance I’m looking at upgrading my current HRV in a simplified setup to a new ERV with a direct ducted setup. Why do you recommend a hybrid setup, with exhaust ports throughout the house but the supply going through the air handler. Could this cause over ventilation and / or fresh air to be improperly distributed throughout the house? Love your videos by the way.
Thanks Sebastian, and as long as you test the flows you can dial in whatever CFM you want. AH distribution means you get an immediate second filtration on the incoming air, and you already have a duct system to deliver everywhere.
If you Are ducting in individual supplies would it then be preferrable to put one in the closet or still better to place exhaust there? ( thinking exhaust might pull in more dust into clothing over time). Why do you yourself prefer not to add an exhaust in the laundry? Is it because the dryer already performs that function periodically?
I thought he was saying that some folks are paranoid about the laundry room being dirty but he is not. You're right though it does exhaust itself sometimes.
I like this discussion. I think, having years of commerical (large volume) and custom home ERV experience, that some people want to believe that ERV’s are magic. That an ERV can somehow perform double or triple duty to address a multitude of IAQ and building pressurization concerns. It is one of many tools in the toolbox. I would not advise to move air into or out of a closet or laundry room. Moreover, making those suggestions can be dangerous at worst, reckless at least. Anybody hear of combustion air or door undercuts?
So, just a thought- about that first thing you said with Vancouver’s code requiring HRV instead of ERV. You said you would strongly recommend ERV, because it’s damp there! Which makes sense. But - I just happened to read just a few minutes ago, on a different site while I was researching all this for myself, a recommendation to specifically use HRV if there is high humidity - •in the winter•. If there might be moisture issues, in the winter. Important qualifier? Since these systems are influenced to some degree by the temperature, and that seems to affect what they are doing and whether heat or humidity is traveling in or out, I imagine that summer humidity would be different from winter humidity, in how they would operate? Is that true? That was what my wondering was, when I came across that because I also was confused initially when I saw that the ERV wasn’t what they recommended for winter time humidity. 🤷🏻♀️ Would be curious to know what you, or others in the know about the systems, might think about that possible little detail.
Winter humidity is actually super dry when you warm that air up to room temp. See here: Humidity Control 101: Psychrometric Wheel Calculator’s Dewpoint and Grains/Pound of Moisture th-cam.com/video/s-VyqdYnEfM/w-d-xo.html
How do you check if your flows are balanced between hvac equipment and the erv fresh air if you put it into your main return? I read they’re suppose to come out with systems that are connected to your air handler but haven’t found any. Also how do you address the inefficiencies of this install method?
In that master bath. You have two outlet Vents. What about conditioned air inlet? Is there not one in the bath? Relying on door gap to bring in air? With a conditioned air vent in that room. The exhaust would no longer pull from the door gap? I am getting ready to vent my bathroom shower on one side and tub on other. I have a remote fan venting outside when needed. Splits into two 6" grills. One placed in front the shower ( to retain some steam and warmth) then. The other just In front the tub. Hvac inlet I guess centered in the room.
Are you familiar with Minotair HRV which has a built in heat pump? The unit exchanges air, dehumidifies, heats & cools, and supports Merv15 filters. Would be interesting to get a video on some these smarter ERV/HRV units like CERV or Minotair
I put my bathroom fans just outside the shower and they create enough airflow in the shower to make you cold. Putting them actually in the shower would be far worse and unless you are dumping 4-6gpm out of that showerhead you are going to freeze while the fan is running.
@@RaglansElectricBaboon Interesting. Terrible website though. You can hardly find a picture of the product anywhere on the site. I had to hit several links to their site to even find it. I'm rather tall though, it would not work for me without taller ceilings.
Love these new, breakdown videos. I saw from a previous post (and from your comments here) that you may have over engineered your system (too many filters?) REALLY looking forward to upcoming vids with your takes on what you did right and what may have been overkill.
Hi Corbett, I wish to check an idea I had, and for which I could not find any information (only a hint in one of you videos where you and your wife talk about the recirculation function of a Broan system). Given your approach, I thought you may have a relevant say about it. Here is my contact and my question : Context : I wish to imrove the confort and Energy Efficiency of a hourse I own. it was built in the '50s and adding air ducts would be difficult in rooms. Corridors are not directly heated in the current setting. Question : Would it be dumb to use a HRV to - pull air out of the Kitchen (level 1), Bathroom (level 2) and maybe Home Office (level 3) - push air in the corridors on 3 levels and use a 2 Spot ERVs to supply rooms with fresh air by pulling it from the corridors when needed based on CO2 level detection. Maybe a simple vent would be enough ? (polluted air would be pushed below the door) Thanks in advance for your feedback !
Your perfect house layout has a lot of showers and baths against outside walls. I was taught never to place large areas of waterproof wall (such as a shower or bath surround) against an outside wall, because it will create condensate and mould issues in that wall. All airtight, all vapour permeable, is what we're being told here.
I’m having a really difficult time finding anyone locally who knows how to size the ductwork for an ERV and I’m not having much luck finding an explanation on any websites or you tube. What is the process for sizing the trunks and branches for the supply and exhaust?
I plan on putting a spot ERV in my basement to help with radon mitigation. It is about a thousand square feet unfinished and I'm looking at the Panasonic whisper comfort 60, a new model that came out last year. It can be placed in the ceiling or on a wall and I'm trying to decide where it will have the most effect high or low? Easiest and with the least amount of turns for ductwork to put it in the ceiling, so I guess there's that consideration of loss of CFM
Think of a centralised HRV/ERV as being a sealed and balanced system. A standard bath fan that is exhausting externally will unbalance the system when turned on and cause short circuiting (ie the return will draw from the bath fan rather than the supply) when off.
I’m working with an old house with a partial basement and no attic. Thinking to duct both supply and exhaust air from my furnace. Can I just pull straight out of the plenum and feed straight into the return? Id love to get more nitpickey over feeding and pulling from certain rooms but even renovating the duct system to feed everything used every last bit of space.
How do you name exhaust flow rates or inlet flow rates for the articular rooms? The only thing I could think of would be the sizing of an exhaust fan for a bathroom or the HRV/ERV itself. but what would control a five CFM exhaust from a closet? Let’s say.
Great question, but an ERV of any brand at all does not 'combat' in my mind, it just resists. Depending on how airtight your home is, the wind may have even more ventilation effect on the home than the ERV does.
What if a home doesn't have central air or heat? (radiant) Where should the fresh air be dumped? Also is it not recommended to hook kitchen hood to an ERV exhaust?
Part of the issue is joist space real estate. In a normal 3000 ft² bungalow, you'll have around 25-30 sheet metal supply runs, some of which can share a joist with each other, most will be on their own in a joist running one way or another. You'll have 5-9 return airs usually - those take up a joist space each and can't, or shouldn't, share the space with anything else, especially plumbing, and definitely not metal. Another joist is lost to the venting for the furnace, and usually the hot water tank will take one as well. Plumbing will be coming down and traveling towards the main stack from all the bathrooms, kitchen, etc. If there's plumbing in a joist cavity, you can only usually get one sheet metal run in, meaning another goes elsewhere. Every single thing I just wrote is determined my the orientation of the walls on the main floor, and has to take in account getting things to code (sheet metal supply runs terminating within 4' of the exterior wall, and really they never get that far out, plus returns being unobstructed and proper pathed out, also clearances for venting). ERVs exhausts and intakes also need clearances. In Ontario Canada, and mostly standard elsewhere, fresh air intakes need to be 10' away from any exhaust. With how cramped the basement sounds based on what I just wrote, adding a doubled up sheet metal duct system, even if it's a bit smaller than a normal duct install, makes for a way more complex basement, wall system, cabinetry upstairs, framing and trim...it all adds up, and real estate can be the biggest commodity there is.
Forgot to mention in that that it's perfectly fine to just take out exhaust from the ductwork, and put fresh air in at the return side before the filter anyways. Saves space and time and the ductwork is going to all those places anyways, most of the time
@@levidobbin5654 wow thanks for the explanation but that's a bit discouraging. This is also why Zehnder seems appealing to me. I might not use all 12-15 of the lines they recommend but I feel the 4" flex pipes would find their way through that labyrinth, at least to supply the bedrooms and exhaust the bathrooms etc. My real problem is that my house is pretty big with 3 levels and I wanted to have zone control. I don't see how inline erv is compatible with that unless maybe I get a little erv for the two bedroom zones. Also wanted to tie dehumidifier in with erv. The local HVAC companies are not pleased.
Great video. Here's a question I've been wondering about ever since I heard of HRV and ERV systems: If I already have supply and return air ducts going in for my heat pump system, why don't I just use those for the ERV/HRV ductwork? You did mention dumping the supply from the ERV into the return air side of the HVAC system, which does make sense to me, but why do you then need separate "return" or "exhaust" vents for the ERV?
you could just use a single exhaust vent for the ERV in the centre of the house (some brands here promote that), but then you still need bath room fans etc. so why not just use it to your advantage. you need to have the exhaust so might as well make it be a bit more useful. having constant airflow going through the bathroom is great. no need to have a separate bath fan.
@@tweake7175 Yeah, I'm not referring to the outside exhaust necessarily. I'm referring to using the cold air return vents that are already in most of the rooms to take the air back to the ERV, instead of running return air ducts to the HVAC system and separate return tubes to the ERV. It seems like a lot of extraneous duct work and extra expense when, logically, you should be able to use the same ductwork for both systems.
IMO - Discussions regarding ventilation strategies would be more practical if prefaced with a warning about favorable and unfavorable conditions or “in my climate zone” or “not all HEX are designed with the same effectiveness.”
On a system like the Broan, could I simply tell it to bring in more than I exhaust, create a small amount of positive pressure, and keep radon from being able to seep into my house? Or not that simple?
I like the short-form videos. I am months away from starting new construction. You mentioned connecting the supply of the ERV to the return side of HVAC return to capture the filtration. When the ERV is operating is it also turning on the air handler of the HVAC system. Getting dual use of main ducts running to all the rooms seems like a good idea. However what about inserting the ERV supply into a separate dehumidifier before connecting to the return side of the HVAC system?
I was wondering the same thing about the ERV connecting into the return of the air handler. Often air handlers in the high efficiency homes don’t run as often. So would think the ERV connected to the return would require the air handler to be running all the time with the ERV. Or the ERV would need to connect to the supply side of the air handler.
@@UserError7861 Yes the main air handler would run whenever the ERV was running. The trade-off is not having to install separate supply ducts from the ERV.
im actually about to move my ERV exhaust vents to my kids bedrooms, and add a fantech bathroom exhaust. I would prefer not to bring in air when exhausting the bathroom on hot humid days. Is there a pressure difference, sure but I still don't believe my house is that tight.
No exhaust vent in the kitchen??? Also, please comment on possible loading of moisture from shower stalls into ERV. Will that compromise it's efficiency? And/or increase maintenance?
Mythbusting ERV vs. HRV: Which Ventilation is Safer for Moisture and Humidity? th-cam.com/video/QOe4lluGwCg/w-d-xo.html And the kitchen exhaust is absolutely necessary, but should have absolutely nothing to do with the ERV.
9:52 Hi, I’ve been scanning your videos and learning much. Any advice on components necessary when using zoned hydronic radiant floor heating by a high-efficient combi-boiler. At this stage of my home construction, no drywall has been installed, the heating system is not installed, spray foam insulation is in all exterior walls and under roof deck. Flex duct supply and return runs , fittings and boots (properly sealed and installed) are located in the ceilings for a/c. The air handler and evaporator will be in the garage attic space (also spray foam insulated). I’m looking to include an ERV, a whole-house humidifier (without ductwork if possible) and a whole-house dehumidifier (among other components if recommended). We’re located in West Michigan, climate zone 5. I can do further research on best practices for installation if I only had a list of the recommended or optimal components. Can you advise what the list would look like? Thank you in advance!
Sorry Doug, no advice from me, I’m not a hydronics guy. House sounds prettt good, just make sure the garage has no air connection with the house when you blower door test (using a zonal pressure test).
With exhaust fan in corner, 2 walls so close, possible impact to fan performance ? Rather does a fan pulling air with lower resistance on one corner but higher resistance on the wall side impact performance? Perhaps there is a way to calculate distance from walls for highest performance..or worse case reduced fan longevity.
Thanks for this video! Are there pros/cons to supplying and venting every room? Bedrooms for example, having fresh air brought into one corner of the room, and "old air" sucked out from another corner?
More ideally, each room would have a center ceiling supply, and exhaust at opposing walls near the floor. This provides clean laminar air flow to the head, pushing floor dust into the exhaust.
Every room that has closable doors needs to have its own balanced supply and exhaust. If the supply and exhaust to a given space are separated by a door, then when the door is shut either you have a draught under the door, or there isn't a big enough gap for a draught and the airflow simply stops.
Can an ERV be used with a central return? If so, how? For example, I could duct the ERV into the central return closet, underneath the filter. Would that be adequate if the air handler blower was set to run continuously?
As Columbo would often say; "Just one more thing"... I do have an additional question that may already be addressed or will be in future posts. You referred to Zehnder as the Ferrari of ERV's (due to performance &/or costs). If one were beginning a home from scratch, would designing it using Zehnder be a question of overkill or one of simplicity (regardless of the costs compared to other systems) in providing dedicated outside air to your home, without added complications of using other systems and integrating into a more budget conscious process?
Zehnder is undisputably the most expensive and elaborate dilution system you can find, and you can’t combine it with other equip like a dehu. Not my choice because I like to play with HVAC like Legos. Zehnder is a brand that doesn’t lock in with the Legos.
@@HomePerformance Hmmm can you explain this in more detail please. Zehnder doesn't dehumidify but they say you can a dehumidifier and have it part of the system. Then a make up air system for a hood vent is separate. Also in this video you show only so much exhaust going out what about all the air needed for the number of people that may come in such as a party of 10? would you not need more air and what comes in must go out?
There are two airstreams with four connections. One must be exhausted to the atmosphere if the conditioned air (intake) is sourced from the restroom. Generally, an ERV is strictly used to temper the fresh air stream (ventilation air) by reusing the conditioned air (intake) to minimize any temperature change within the space. That is it in a nutshell.
I think that the emphasis is CO2 buildup and odor control so IMO, exhaust the stinky or humid areas, supply the populated areas where people need the fresh air, then let that air migrate towards the exhaust points. Ventilating a closet is probably not a common practice but I suppose the closet could have louvred bi-fold doors and let the air exchange thru natural convection. The laundry room has a mechanical exhaust by virtue of the Clothes Dryer, and is a low occupancy area so why even bother.
If someone connects the ERV to the HVAC ductwork will they have to run the HVAC fan 24/7 or will the ERV be able to push/pull on its own when the HVAC is not running?
Am I correct to assume that you are talking about a house with central AC/Heat? What about if you're using ductless cooling and heating, like a mini split?
Carpet as I can’t imagine your ERV fan can overcome your duck systems static pressure if you are dumping your ERV supply into the return of your HVAC system you must be running the HVAC blower constantly isn’t that an issue with energy use and wearing out your blower?
Are there some climates where HRVs and ERVs aren't worth the extra install costs and running costs? In Auckalnd our summers are mild and winters not bad either so it doesn't seem cost effective here. Would you agree just a positive pressure ventilation system would be better in Auckland?
Not climate, but home characteristics- if your home is tight enough that bath exhaust fans will cause suction problems, you must have an ERV to exhaust from bathrooms and balance. If not tight enough for that, then stick with simpler means of getting fresh air. Watch this: th-cam.com/video/lnOCAPPVT5g/w-d-xo.htmlsi=yRBsI7JJ7y2h8Heu
@@HomePerformance ph, let me clarify. I mean ERV vs supply only systems. MY point is, I think in Auckland it's not worth the extra cost to try and recover heat from the exhaust air.
I realize that I've been designing systems placing the supply and exhaust adjacent to each other on the same wall. is this going to cause short circuiting? ruh roh
I'm about to buy and rehab a 2000 sq ft 1960's pier and beam house in south texas. I will be replacing all duct work and HVAC system. HVAC is currently in a closet in a bedroom, with return in the hall. Would an ERV be worth it or should I just exhaust everything outside? I'm planning on installing a stand alone dehumidifier in either the attic or an aprilaire wall mounted one.
When installing the fresh air supply output of the ERV in the HVAC air handler return path, does it matter where the air handler filer is? I would think that the common location of in the return grill will cause a significant low pressure situation when it is running, increasing as the filter fills up. I think some people have the filter at the blower motor, which is a different situation. Should those with a grill filter have a box added at the blower to accommodate a filter move? The simplified installations (retrofit) have both the fresh air supply output and the room air exhaust in the central air handler system. It seems to me 0.5 in wc would really mess with the ERV fans. Thoughts? I have looked at a couple of install manuals, but none of them have made a comment on that central filter location and its effect on performance and balancing.
Exactly, Larry- filter grilles are only for not using the return for anything else. Filter slot is so much more versatile. Also, 0.5 would be supply + return, so ideally you only have 0.1”wc in the return trunk.
@@HomePerformance I will check where and how large that pressure drop appears soon. I suspect that making the filter location change is in order. Being in the attic, makes it not such a fun chore to change the location by adding the filter box at the inlet. I have been also trying to decide if I can economically change the blower motor to be more efficient (EC or DC) such that i can run it at 1/2 speed in fan / heat mode with 1/8 the power while the ERV is active 25% to 100% of the time vs drawing 400W all day and making more noise than is desirable due to the air velocity being a bit higher than needed.
When these units say up to 75% efficiency is that only temperature transfer. How do we find a spec for humidity? I'm on the gulf coast and need ventilation but humidity is a huge issue already without it.
Only some manufacturers test for that, and probably not all of them list it if they're not happy with the results. Broan does, and Renewaire too I believe. You should spec a dehumidifier, I almost guarantee the ventilation will increase your home's humidity levels.
@@HomePerformance I already have both. Massive humidity issues... Working on iterating after 6 years of problems. - Builder Install: Unfiltered passive intake into unfiltered air handlers. Filter back grills. - Rev 1: Capped one wall penetration, UltraAire 120V ventilating dehu on the open intake ducted into air handlers, SantaFe Classic in Garage below home, five 70 pint retail dehumidifiers around house. - Planned Rev 2: Dual UltraAire 70's and a Broan ai ERV all ducted into air handlers, SantaFe Classic in Garage below home. Unfortunately at this point I'm stuck retrofitting for damage control. Targeting < 50%rh.
YES, which is why I advocate ducting the fresh air into the return of the central air handler- it'll get there. Otherwise, a totally separate duct system is required to deliver it to each bedroom and office.
@@HomePerformance so, the returns from baths and closets get fed into ERV, fresh air from outside also gets fed into ERV... ERV transfers the energy (hot or cold) from baths and closets to fresh air from outside.. and this outside air, now with energy transferred to it gets fed as the return to the home HVAC system..... Will the HVAC be able to appreciate/ detect the return air temp and adjust itself ?
@@jimmyphilip2340 No. The frest air is tempered and mixing with the room temp air circulating in the return duct. The blended air will eventually change the temperature at the thermostat.
In your example you put an exhaust in the washer/dryer room, but you said that you would not actually recommend putting one in that room. Why not? I’m just looking for additional information and not disagreeing with you.
Yes you do, Fred- otherwise it won’t go through the filter, get mixed and conditioned, and get distributed through the supply ducts. It’d just turn the other direction and follow the path of least resistance out through the return grille.
@@HomePerformance but if you had one way dampers fitted they would close when the hvac was off and air would be forced to go the correct way, or would that put to much restriction on it?
But this way you make a messy disbalance of in/out volumes. Will not work in tight envelope houses. Good extraction hood can do hourly cfm of an erv/hrv in few minutes. And in cold climates this will not work, might freeze the unit as it sucks a lot of cold air and there is no exhaust to warm it. Better to do extraction hood with carbon filters, that dumps air back in the house and have erv/hrv exhaust in kitchen. Well at least thats how we do it Europe.
won't it really depends in what part of the world one actually live? isn't all about the environment ones house is placed? an HRV is a better choice if you often have an overly humid house during winter, while an ERV is superior if your house is too dry...
![[Live สด] การออกรางวัลสลากกินแบ่งรัฐบาล งวดวันที่ 16 พฤศจิกายน 2567](http://i.ytimg.com/vi/wPd7VFfWHIA/mqdefault.jpg)
I work for a company that helps people with mold illness and install ERV’s. You are quickly becoming my favorite channel. Please keep up this content.
Hey thanks buddy! Will do.
I could use some information about reducing indoor mold spores. What is the name of your company? Do you have any suggestions?
Great video and completely understood. Would like to see a second part on this of sizing and location of supply air coming in at the best locations to assure operable balancing. Sizing of lines, suggestions on proper vent grills or manual open closed vents.
16 yr HVAC service technician here. It’s infuriating to find out that my common sense has been correct from day one about vent locations and the need for ervs. I’ve always wondered why the ‘fart fan’ is always located closest to the toilet rather than just over the shower. Dumb! It’s not for odors, it’s for humidity removal. Period. Great video.
Thanks man, happy to hear it
Amazing video. Would really love for you to do a follow up and discuss harmony between location of ERV & HVAC registers /returns.
Thanks Al, got it on the list
@@HomePerformance Yes please! Also, where are the supplies?
Either bedrooms, or dump it all into the central duct return
@@HomePerformance Wouldn't ducting into the return throw a lot of new , moist air (from the outside) into the unit, vs into the supply and letting it get comingled with other, already dehumidifier air and then sucked back through the normal returns?
@@HomePerformanceisn’t it a bit more nuanced, exactly the way you discussed flow through the bathroom, you’ll want to ensure that all the living spaces have good air flow? I’m referring to dedicated supplies.
We didn't think the efficiency in the Atlanta area would justify an erv. We have that exact pattern for exhaust. Only difference is we use fresh air intake on our dehumidifier and exhaust using a central bath fan ducted to closets and bathrooms. We set both fan side of the dehumidifier and the central exhaust on the same controller. As one goes up the other goes up. We have it set about 25 cfm higher intake then what the exhaust is set.
Thoughts on sensors to control ventilation? I like the idea of controlling the ERV with a combo of indoor and outdoor IAQ sensors, both to save money by not needlessly over ventilating and to shut down the system during events like wildfires or dust storms.
I second it. Controls are not well understood but are necessary to any successful ventilation strategy
Great video and channel! I found this channel after Corbett's recent appearance on Mat Risinger's Build Show. Catching up on all of the great videos here now!
Thanks for your channel. I'm actually doing a major rebuild on a semi-remote island near Vancouver. It's about as airtight as possible with a rebuild, with hydronic heating, and will require all sorts of creative installation to get the lines where they need to get in a building not designed for HRV/ERV. I am relying on your channel, as getting anyone out here to do the work is impossible, so I'll have to become an HRV expert pretty quickly. 🙂
Having 130 continuous, and a 160 ERV is not enough headroom for a party or any real change in CFM. Also, running that close to capacity will be louder, and potentially using more energy than running a 300 CFM machine at 130, while having meaningful extra for emergencies. Provided that the unit has nice control range and not unreasonable pricing for that additional capacity. I ran a 360 at 150, which is unnoticable 24/7(~30W), but has plenty of umpf for when I need a boost (almost 150W).
I happen to know from experience it is enough, I’ve lived with ERVs for seven years in two homes.
What 360 are you referring to? That’s not a residential sized unit.
Also, what emergencies are you imagining?
@@HomePerformance my dog's create some emergencies from time to time
Cleaning is not optional, of course
Open a window, Koo Koo. You are so cute when you’re serious. Simply, adorable
Great video. However, I don't actually see placement of the supply grilles covered in the video (as title suggests). Lots of detail on unique CFMs per exhaust, but where did you place your supplies and at what CFMs? Possibly you can just post an image of the floor plan with supplies and exhausts. Cheers.
Yeah, I was wondering if I'd missed the supply side but its not there.
Also, I've got a 'shower dome' which is awesome & keeps nearly all of the humidity inside the shower cubicle. I haven't seen any ERV/HVAC people discussing how this changes things.
In the US, we size our ventilation off numbers for exhaust, then fit the supply to that (as long as ASHRAE 62.2 does not exceed, in which case use bigger target).
In Europe and even Canada, it’s opposite- they size based on supply targets and fit exh to it.
I do mention, but easiest (and best imo) is to inject fresh air to return of central HVAC ductwork. Otherwise just make each room either supplied or exhausted as far from the door as is feasible.
Looking for some clarification. Really like the idea of an ERV replacing the bathroom exhaust fans but getting mixed feedback when I talk to professionals in my area. The ME who designed my system says here in eastern NC we can’t do that. The installers in the area say the ERV can supplement but not replace the standard bathroom exhaust. Broan’s website advises against ERVs exhausting humid air. But this video and a high performance video says we can. Any insights you can offer? Thanks for information and the channel. Really appreciate it.
Thinking same. With erv, humidity in shower would be redistributed to entire house.
End of the day did not pursue using the ERV as bathroom exhaust as that was against code.
@BenNC22 it is not against code. It is built into the Int’l Mech Code.
@@HomePerformance it is where I am. Multiple code officials in my county and hvac pros stated definitely bath exhaust must be directly vented outside. ERV was specifically not allowed.
@BenNC22 I believe they misunderstand ERVs, or their own code, or probably both. You can always appeal for an exception.
Wow! I have watched this 3 times! I’m in the Eastern-most city in the US (Eastport ME) and am having to figure this all out on my own! I have spent days researching and now are not going to do spot units. This is such a head jam for a novice (to talk positively about myself)! Anyone know of a contractor in Washington County or NB Canada? That’s where my search went last night! I’m putting in 3 single ductless Mitsubishi units and full envelope closed cell insulation. I love my people but they know less than me at this point. 😢 I am subbing out all my work (I’m the Gen Contr😅) and have learned so so much but this keeps me up at night!
You are not alone my friend- many of our viewers and clients are the most savvy people in their entire town. Like you, they all have to push their builders and subcontractors to do new and better things.
Thanks very much for watching, happy we're helping you with your project. Try these resources:
homediagnosis.tv/pro
maineindoorair.org/member-directory/
Best of luck!
Ugggg I FEEL YOU~! 🥴
Thanks for the video. In the future I will add a CERV2 or other ERV due to cost, but what I've been trying to figure out is exhaust. My thought is that I could use my bath fan holes (4" ducts with backdraft damper flaps) since they are already there for exhaust. I also have a return in the kitchen/great room for my whole house dehumidifier I could use to exhaust the kitchen. Those are already there. Currently, I have a Sante fe ultra 70 with 8" fresh air and 10" return that goes into a tempering box which then enters the dehumidifier and then enters the return on my air handler. Fresh air intake, return, and my air handler all use their own merv 16 filters. It is all a retrofit except the A/C and I'm looking at how to make improvements later. I've been using air quality monitors to measure C02 where we sleep and VOC's to dial in my amount of fresh air coming in which I do by opening or closing the amount of return air. The dehum fan I run 24/7 and my ecobee calls for dehum when needed. So, anyway, any suggestions with setting up whole home dehumidifiers and adding an ERV later would be cool. Also, I recommend looking at the CERV2 from Build Equinox if you haven't. Expensive, but it is awesome! Unfortunately, the company my builder used greatly oversized my air conditioner. I'm using dehum mode on it and I've lowered the fan speed since I literally never need stage 2 to get more run time and dehum. It's fun to sort out, but maybe you can talk about ideas for retrofits like in our situation. Take care keep up the great videos!!!
I love the Cerv2 we put into our office and I'll be ordering another for my house and I'm in a similar boat to what you've said above.
The only thing, if I may, I would consider adding would be a zone damper and put your bathrooms on that zone and then you have a second zone with everything else.
What you've described is what I originally planned, but after using the Cerv2 unit at our office now for a prolonged time, I would definitely only want the bathrooms to be pulled from if the unit wasn't in recirc mode. This thing is super smart and does an amazing job... I'm adding the outdoor sensor actively as there is one event happening every day at a certain time that seemingly is coming from outside the building... Someone I never would have known or paid attention to. I love the Cerv2 and will be coupling it with a heat pump unit at some point in my setup that will cover the majority of the load.
In any case, I am not being critical at all of what you said, but this is something I had to adjust after using the Cerv unit for a while so I thought I'd share my speed bump.
Edit: I thought I would mention/remind that the system you always hear people talk about generally has the replaceable core vs our much more programmable heat pump system. So we don't have anything to replace, but our air streams work differently
.. that's the reason I mention the above and the video goes against what I said... The core exchanges much of that energy and exhausts the rest... Ours very well might be simply recirculating depending on the outside air variables.
One thing I noted from your current setup is that your dehumidifier supply puts its dry air into your HVAC return. This isnt ideal since you've removed your A/C's opportunity to dehumidify. Also, I think you mentioned your dehumidifier is always on. This will push air over your cool/wet a/c coils drying them thus pushing water back into your home. I found it counterintuitive but it's fine to add a little more static pressure to your supply (in most cases). Hope this helps
@@DonovanSexton so some sneaky dude is taking a stinky dump every day and it's smelling up the house? Or are they smoking up outside? Sorry I couldn't tell. CERV2 is so cool. Tye is the man. Maybe zone dampers are the way to go.
Good point, Don- the Broan and Zehnder ERVs both have recirc modes that would need to be disabled in those scenarios
@@DarenSpinelle Not exactly. The evap coil will be removing less latent heat (moisture) from the drier air so an added benefit is that the a/c can be down size due to a smaller total cooling load.
Great information as always Corbett, any chance there is a follow up video to this one that describes optimal supply grille placement?
Really love your video topics and the vast amount of information they provide. Would be great if you can do something about building a pretty good air tight house with a fireplace or wood stove or both. Is this possible to achieve.
Thanks
Thursday’s video will hit home for you, Robert- but short answer is that will not work in many cases. Depressurization sensitivity is the issue once you get airtight enough.
My contractor and electrician were incredulous when I insisted that the exhaust fan/lights be put in the shower, but I showed them that it was rated for it, so they did it. Keeps the mirrors dry!
Hell yeah man
You have mentioned a few times on the comments that there shouldn’t be a ERV exhaust in kitchen. Can you provide an explanation why!? Or maybe you already have a video where you explain this!?
Thank you.
There should be a powerful exhaust fan over the cooktop, dumping outside. If you have that, whether or not there’s a 25 or 40 cfm ERV exhaust in the space is not a big deal.
@@HomePerformance So you are not against having an ERV exhaust in the kitchen!? It’s just if you have proper exhaust over the range with a proper makeup air system there is no need for it!
Exactly right
Okay. But, what would you do if you want to be able to have the steam/humidity stay in the bathroom for a bit? My wife has super curly hair, and it helps when she is styling it. I like to take baths and keep the fan off so the air is more humid and warm. Can you control that somehow without messing up the rest of the system?
A register with a closable damper on it would work, but you'd have to be on top of opening it again or you'd get moisture issues in the room.
In a well-designed home with the right equipment installed, you’re able to do things like this without big consequences, as long as you know how to make the system work for you.
Sir, this is a design decision, if you want a steam room to double as a restroom, then so be it. It’s your castle. I think you are asking the right questions. And remember, controls are a key to automation. So that closable damper can be on a sensor. Just sayin. Keep a healthy distance from zealots. They smell funny.
4:04 - - vent is best in corner over tub (it grabs as much steam a possible) 🙂
4:39 - - vent is best in corner over shower (vanity mirror will never fog up) 😊
4:50 - - mistake to put vent in middle of bathroom (less efficient/effective) 😶🌫
You have nearly half your total exhaust in the bedroom / ensuite and none in the kitchen. It seams that cooking odors would tend to migrate into the bedroom.
I’m assuming the kitchen would have a separate exhaust with high cfm and separate make up air system. But you make a good point. Given the proximity lingering odors and other vocs when not cooking would naturally be pulled into the master. I wish Corbett would address this.
Bedrooms are positive pressure zones, bathrooms neg pressure. When cooking, the kitchen becomes neg pressure zone because of the massive exhaust hood with dedicated make up air (400 cfm, 2.7 times more powerful than the ERV).
The intention with all ventilation strategies is to dilute the breathable air, not scrub it. ERVs are generally designed for Class 1 air. FYI - It would be best to post a comment of this nature in a form of a question. That way you don’t sound like a neophyte. Cheers!
@@HomePerformancewouldn't it be more efficient and effective if you run the air from the kitchen exhaust hood through a whole house dehumidifier, which takes the fresh air from the inlet of the ERV/HRV equipment? That way you are keeping the building envelope closed.
I have a question regarding the ERV exhaust intakes for closets. I was taught that HVAC returns are discouraged even in walk-in closets as that accumulates dust in the closet contents. Would ERV exhaust intakes create a similar issue despite the lower CFM flow relative to an HVAC return? Not that I would have to worry about that since code required HVAC supplies to walk-in closets which have exterior walls in my newly built house. That bit of code adherence was ironic given the mythical Manual J/S submitted for my house.
Great video. So if you exhaust from some rooms and supply others, the air would need to make its way through the loop. What if the house has minisplits in every room, or say VRF/multisplit type aircon with the only ducted system being the ERV? Would that still be enough or would there be a need to exhaust/supply every room?
splits will condition the air and remove some moisture however you still need to exchange the air otherwise co2 will build up and other pollutants. With a good temperature exchanger in the HRV/ERV, the temperature of the conditioned air should be retained to a large extent.
if your running mini splits then you need exhaust/supply ventilation in every room. thats exactly what i have in my home.
@@bevthebuilder5457 “Should be” is a statement of hope. That’s not how physics works. Assuming a variable capacity system can “control” the temperature and heat energy in the air is a fundamental misunderstanding of Psychrometrics. Furthermore, it’s all about a given manufacturer’s testing and performance capacity tables being available for scrutiny and after installation commissioning. If you can’t predict it, why do it.
Great Video! Quick question with regard to this topic. How do you factor in a large vent hood over the cooking range? Some of those are around 1200cfm. Do you offset for these temporary draws?
Another great one.
You're a beast, Corbett.
Thank you so much for putting this video out for us. 😏
Hey thanks my friend- glad it might help
Great video. What’s the strategy for handling makeup air for a clothes dryer?
Depends on air tightness. It’s not an issue in a leaky home. Tighten things up and mostly your options are: add dedicated passive makeup air on a pressure switch, buy a heat pump dryer (best option for energy), or find another way to get air inside. For instance, Lunos ductless HRV fans allow about 35 cfm each as a passive makeup air mode. The fan turns off when it senses the pressure difference (I called the US rep, 475, to find out). That’s 140 cfm with four fans, about enough for a dryer.
I have seen reports of new ducted HRVs that will ramp up exhaust when they sense a makeup air demand.
buy the heat pump dryer, you wont regret it.
@@bevthebuilder5457 which one? Miele models are too tiny for the average American consumer
FYI, Connor, the Lunos isn’t one of my recs because it doesn’t set up a consistent pressure imbalance. So you’d still have to use bath fans, which in airtight homes is a nono.
Disagree on the tiny thing- it holds 17 lb wet I think- efficiency of form helps. Also, the Miele washer it pairs with spins faster than any other residential dryer, so the clothes start drier to begin with.
@Home Performance I’m looking at upgrading my current HRV in a simplified setup to a new ERV with a direct ducted setup. Why do you recommend a hybrid setup, with exhaust ports throughout the house but the supply going through the air handler. Could this cause over ventilation and / or fresh air to be improperly distributed throughout the house? Love your videos by the way.
Thanks Sebastian, and as long as you test the flows you can dial in whatever CFM you want. AH distribution means you get an immediate second filtration on the incoming air, and you already have a duct system to deliver everywhere.
You nailed it once again, ❤
Thanks!
Exhaust nicely covered, can we see supply? Thxs. PS, about 30 seconds of piano playing for a ballerina might be a nice outro...
If you Are ducting in individual supplies would it then be preferrable to put one in the closet or still better to place exhaust there? ( thinking exhaust might pull in more dust into clothing over time). Why do you yourself prefer not to add an exhaust in the laundry? Is it because the dryer already performs that function periodically?
I would ignore the closet
I thought he was saying that some folks are paranoid about the laundry room being dirty but he is not. You're right though it does exhaust itself sometimes.
I like this discussion. I think, having years of commerical (large volume) and custom home ERV experience, that some people want to believe that ERV’s are magic. That an ERV can somehow perform double or triple duty to address a multitude of IAQ and building pressurization concerns. It is one of many tools in the toolbox. I would not advise to move air into or out of a closet or laundry room. Moreover, making those suggestions can be dangerous at worst, reckless at least. Anybody hear of combustion air or door undercuts?
A lot of GOOD food for thought. Thank you.
Thanks Mark
Great teacher. Thank you for sharing. Take care.
So, just a thought- about that first thing you said with Vancouver’s code requiring HRV instead of ERV. You said you would strongly recommend ERV, because it’s damp there! Which makes sense.
But - I just happened to read just a few minutes ago, on a different site while I was researching all this for myself, a recommendation to specifically use HRV if there is high humidity - •in the winter•. If there might be moisture issues, in the winter. Important qualifier?
Since these systems are influenced to some degree by the temperature, and that seems to affect what they are doing and whether heat or humidity is traveling in or out, I imagine that summer humidity would be different from winter humidity, in how they would operate? Is that true?
That was what my wondering was, when I came across that because I also was confused initially when I saw that the ERV wasn’t what they recommended for winter time humidity.
🤷🏻♀️
Would be curious to know what you, or others in the know about the systems, might think about that possible little detail.
Winter humidity is actually super dry when you warm that air up to room temp. See here:
Humidity Control 101: Psychrometric Wheel Calculator’s Dewpoint and Grains/Pound of Moisture
th-cam.com/video/s-VyqdYnEfM/w-d-xo.html
How do you check if your flows are balanced between hvac equipment and the erv fresh air if you put it into your main return? I read they’re suppose to come out with systems that are connected to your air handler but haven’t found any. Also how do you address the inefficiencies of this install method?
In that master bath. You have two outlet Vents. What about conditioned air inlet? Is there not one in the bath? Relying on door gap to bring in air?
With a conditioned air vent in that room. The exhaust would no longer pull from the door gap?
I am getting ready to vent my bathroom shower on one side and tub on other. I have a remote fan venting outside when needed. Splits into two 6" grills. One placed in front the shower ( to retain some steam and warmth) then. The other just In front the tub.
Hvac inlet I guess centered in the room.
Heat/cool grille decisions are governed by the Manual J calc.
Maybe not the right forum for this question…but where would one dump the incoming air for houses using mini-splits?
Are you familiar with Minotair HRV which has a built in heat pump? The unit exchanges air, dehumidifies, heats & cools, and supports Merv15 filters. Would be interesting to get a video on some these smarter ERV/HRV units like CERV or Minotair
Dump it near the minisplit, then it’ll get grabbed and distributed with the bigger airflow
I put my bathroom fans just outside the shower and they create enough airflow in the shower to make you cold. Putting them actually in the shower would be far worse and unless you are dumping 4-6gpm out of that showerhead you are going to freeze while the fan is running.
Try a showerdome instead. They're awesome.
@@RaglansElectricBaboon Interesting. Terrible website though. You can hardly find a picture of the product anywhere on the site. I had to hit several links to their site to even find it.
I'm rather tall though, it would not work for me without taller ceilings.
Love these new, breakdown videos. I saw from a previous post (and from your comments here) that you may have over engineered your system (too many filters?) REALLY looking forward to upcoming vids with your takes on what you did right and what may have been overkill.
Thx Eric
Hi Corbett,
I wish to check an idea I had, and for which I could not find any information (only a hint in one of you videos where you and your wife talk about the recirculation function of a Broan system). Given your approach, I thought you may have a relevant say about it. Here is my contact and my question :
Context : I wish to imrove the confort and Energy Efficiency of a hourse I own. it was built in the '50s and adding air ducts would be difficult in rooms. Corridors are not directly heated in the current setting.
Question : Would it be dumb to use a HRV to
- pull air out of the Kitchen (level 1), Bathroom (level 2) and maybe Home Office (level 3)
- push air in the corridors on 3 levels
and use a 2 Spot ERVs to supply rooms with fresh air by pulling it from the corridors when needed based on CO2 level detection. Maybe a simple vent would be enough ? (polluted air would be pushed below the door)
Thanks in advance for your feedback !
In practice, if you put the exhaust in the shower, can you feel air movement leading you to feel cold while in the shower?
If there’s no door or curtain, yes
Your perfect house layout has a lot of showers and baths against outside walls. I was taught never to place large areas of waterproof wall (such as a shower or bath surround) against an outside wall, because it will create condensate and mould issues in that wall.
All airtight, all vapour permeable, is what we're being told here.
I’m having a really difficult time finding anyone locally who knows how to size the ductwork for an ERV and I’m not having much luck finding an explanation on any websites or you tube. What is the process for sizing the trunks and branches for the supply and exhaust?
I plan on putting a spot ERV in my basement to help with radon mitigation. It is about a thousand square feet unfinished and I'm looking at the Panasonic whisper comfort 60, a new model that came out last year. It can be placed in the ceiling or on a wall and I'm trying to decide where it will have the most effect high or low? Easiest and with the least amount of turns for ductwork to put it in the ceiling, so I guess there's that consideration of loss of CFM
In a more basic setup, is it still ideal to have a standard bath fan over the shower for steam purposes?
Think of a centralised HRV/ERV as being a sealed and balanced system. A standard bath fan that is exhausting externally will unbalance the system when turned on and cause short circuiting (ie the return will draw from the bath fan rather than the supply) when off.
Love this! Thanks for an Aussie
I’m working with an old house with a partial basement and no attic. Thinking to duct both supply and exhaust air from my furnace. Can I just pull straight out of the plenum and feed straight into the return? Id love to get more nitpickey over feeding and pulling from certain rooms but even renovating the duct system to feed everything used every last bit of space.
How do you name exhaust flow rates or inlet flow rates for the articular rooms? The only thing I could think of would be the sizing of an exhaust fan for a bathroom or the HRV/ERV itself. but what would control a five CFM exhaust from a closet? Let’s say.
Thanks for sharing your expertise man!
In a heavy wind unprotected coastal environment. How much can an "ai" ERV combat the contently changing wind lands effecting pressure on the house?
Great question, but an ERV of any brand at all does not 'combat' in my mind, it just resists. Depending on how airtight your home is, the wind may have even more ventilation effect on the home than the ERV does.
What if you have a fogless mirror? Would you still place the exhaust in the same place?
What if a home doesn't have central air or heat? (radiant) Where should the fresh air be dumped? Also is it not recommended to hook kitchen hood to an ERV exhaust?
So if you dump in to the return you have to run the air handler when the ERV is running as well?
perhaps you’ve addressed this before but I was curious about why you don’t recommend a separate dedicated ERV system
Because I’ve done it, Dragon- in our forever home. Ducted it myself with hard pipe, and I can attest that the benefits do not outweigh the costs.
Part of the issue is joist space real estate. In a normal 3000 ft² bungalow, you'll have around 25-30 sheet metal supply runs, some of which can share a joist with each other, most will be on their own in a joist running one way or another. You'll have 5-9 return airs usually - those take up a joist space each and can't, or shouldn't, share the space with anything else, especially plumbing, and definitely not metal. Another joist is lost to the venting for the furnace, and usually the hot water tank will take one as well.
Plumbing will be coming down and traveling towards the main stack from all the bathrooms, kitchen, etc. If there's plumbing in a joist cavity, you can only usually get one sheet metal run in, meaning another goes elsewhere.
Every single thing I just wrote is determined my the orientation of the walls on the main floor, and has to take in account getting things to code (sheet metal supply runs terminating within 4' of the exterior wall, and really they never get that far out, plus returns being unobstructed and proper pathed out, also clearances for venting).
ERVs exhausts and intakes also need clearances. In Ontario Canada, and mostly standard elsewhere, fresh air intakes need to be 10' away from any exhaust. With how cramped the basement sounds based on what I just wrote, adding a doubled up sheet metal duct system, even if it's a bit smaller than a normal duct install, makes for a way more complex basement, wall system, cabinetry upstairs, framing and trim...it all adds up, and real estate can be the biggest commodity there is.
Forgot to mention in that that it's perfectly fine to just take out exhaust from the ductwork, and put fresh air in at the return side before the filter anyways. Saves space and time and the ductwork is going to all those places anyways, most of the time
@@levidobbin5654 wow thanks for the explanation but that's a bit discouraging. This is also why Zehnder seems appealing to me. I might not use all 12-15 of the lines they recommend but I feel the 4" flex pipes would find their way through that labyrinth, at least to supply the bedrooms and exhaust the bathrooms etc.
My real problem is that my house is pretty big with 3 levels and I wanted to have zone control. I don't see how inline erv is compatible with that unless maybe I get a little erv for the two bedroom zones. Also wanted to tie dehumidifier in with erv. The local HVAC companies are not pleased.
@@HomePerformance Thanks Corbin. What should I do if I want to have zones?
Great video. Here's a question I've been wondering about ever since I heard of HRV and ERV systems: If I already have supply and return air ducts going in for my heat pump system, why don't I just use those for the ERV/HRV ductwork? You did mention dumping the supply from the ERV into the return air side of the HVAC system, which does make sense to me, but why do you then need separate "return" or "exhaust" vents for the ERV?
you could just use a single exhaust vent for the ERV in the centre of the house (some brands here promote that), but then you still need bath room fans etc. so why not just use it to your advantage. you need to have the exhaust so might as well make it be a bit more useful. having constant airflow going through the bathroom is great. no need to have a separate bath fan.
@@tweake7175 Yeah, I'm not referring to the outside exhaust necessarily. I'm referring to using the cold air return vents that are already in most of the rooms to take the air back to the ERV, instead of running return air ducts to the HVAC system and separate return tubes to the ERV. It seems like a lot of extraneous duct work and extra expense when, logically, you should be able to use the same ductwork for both systems.
@@r.j.bedore9884 yes. Most just use the hvac system to ventilate.
Kitchen system is separate due to its bursty (and greasy) nature?
GREASY AND BURSTY!!! I love it, using that from now on. But yes.
IMO - Discussions regarding ventilation strategies would be more practical if prefaced with a warning about favorable and unfavorable conditions or “in my climate zone” or “not all HEX are designed with the same effectiveness.”
Great information!
On a system like the Broan, could I simply tell it to bring in more than I exhaust, create a small amount of positive pressure, and keep radon from being able to seep into my house? Or not that simple?
I like the short-form videos. I am months away from starting new construction. You mentioned connecting the supply of the ERV to the return side of HVAC return to capture the filtration. When the ERV is operating is it also turning on the air handler of the HVAC system. Getting dual use of main ducts running to all the rooms seems like a good idea. However what about inserting the ERV supply into a separate dehumidifier before connecting to the return side of the HVAC system?
I don't see why not.
I was wondering the same thing about the ERV connecting into the return of the air handler. Often air handlers in the high efficiency homes don’t run as often. So would think the ERV connected to the return would require the air handler to be running all the time with the ERV. Or the ERV would need to connect to the supply side of the air handler.
@@UserError7861 Yes the main air handler would run whenever the ERV was running. The trade-off is not having to install separate supply ducts from the ERV.
im actually about to move my ERV exhaust vents to my kids bedrooms, and add a fantech bathroom exhaust. I would prefer not to bring in air when exhausting the bathroom on hot humid days. Is there a pressure difference, sure but I still don't believe my house is that tight.
No exhaust vent in the kitchen??? Also, please comment on possible loading of moisture from shower stalls into ERV. Will that compromise it's efficiency? And/or increase maintenance?
Mythbusting ERV vs. HRV: Which Ventilation is Safer for Moisture and Humidity?
th-cam.com/video/QOe4lluGwCg/w-d-xo.html
And the kitchen exhaust is absolutely necessary, but should have absolutely nothing to do with the ERV.
9:52 Hi, I’ve been scanning your videos and learning much. Any advice on components necessary when using zoned hydronic radiant floor heating by a high-efficient combi-boiler. At this stage of my home construction, no drywall has been installed, the heating system is not installed, spray foam insulation is in all exterior walls and under roof deck. Flex duct supply and return runs , fittings and boots (properly sealed and installed) are located in the ceilings for a/c. The air handler and evaporator will be in the garage attic space (also spray foam insulated). I’m looking to include an ERV, a whole-house humidifier (without ductwork if possible) and a whole-house dehumidifier (among other components if recommended). We’re located in West Michigan, climate zone 5. I can do further research on best practices for installation if I only had a list of the recommended or optimal components. Can you advise what the list would look like? Thank you in advance!
Sorry Doug, no advice from me, I’m not a hydronics guy. House sounds prettt good, just make sure the garage has no air connection with the house when you blower door test (using a zonal pressure test).
Thank you so much for these videos! 🙌🏻 Super helpful
With exhaust fan in corner, 2 walls so close, possible impact to fan performance ? Rather does a fan pulling air with lower resistance on one corner but higher resistance on the wall side impact performance? Perhaps there is a way to calculate distance from walls for highest performance..or worse case reduced fan longevity.
Thanks for this video! Are there pros/cons to supplying and venting every room? Bedrooms for example, having fresh air brought into one corner of the room, and "old air" sucked out from another corner?
More ideally, each room would have a center ceiling supply, and exhaust at opposing walls near the floor. This provides clean laminar air flow to the head, pushing floor dust into the exhaust.
Every room that has closable doors needs to have its own balanced supply and exhaust. If the supply and exhaust to a given space are separated by a door, then when the door is shut either you have a draught under the door, or there isn't a big enough gap for a draught and the airflow simply stops.
Can an ERV be used with a central return? If so, how? For example, I could duct the ERV into the central return closet, underneath the filter. Would that be adequate if the air handler blower was set to run continuously?
As Columbo would often say; "Just one more thing"... I do have an additional question that may already be addressed or will be in future posts. You referred to Zehnder as the Ferrari of ERV's (due to performance &/or costs). If one were beginning a home from scratch, would designing it using Zehnder be a question of overkill or one of simplicity (regardless of the costs compared to other systems) in providing dedicated outside air to your home, without added complications of using other systems and integrating into a more budget conscious process?
Weirdly worded question bro
Zehnder is undisputably the most expensive and elaborate dilution system you can find, and you can’t combine it with other equip like a dehu. Not my choice because I like to play with HVAC like Legos. Zehnder is a brand that doesn’t lock in with the Legos.
@@HomePerformance Hmmm can you explain this in more detail please. Zehnder doesn't dehumidify but they say you can a dehumidifier and have it part of the system. Then a make up air system for a hood vent is separate. Also in this video you show only so much exhaust going out what about all the air needed for the number of people that may come in such as a party of 10? would you not need more air and what comes in must go out?
Can I exhaust and intake my HRV to the return side of my HVAC system?
Yes, that’s my recommended way, Skyler
There are two airstreams with four connections. One must be exhausted to the atmosphere if the conditioned air (intake) is sourced from the restroom. Generally, an ERV is strictly used to temper the fresh air stream (ventilation air) by reusing the conditioned air (intake) to minimize any temperature change within the space. That is it in a nutshell.
I think that the emphasis is CO2 buildup and odor control so IMO, exhaust the stinky or humid areas, supply the populated areas where people need the fresh air, then let that air migrate towards the exhaust points. Ventilating a closet is probably not a common practice but I suppose the closet could have louvred bi-fold doors and let the air exchange thru natural convection. The laundry room has a mechanical exhaust by virtue of the Clothes Dryer, and is a low occupancy area so why even bother.
If someone connects the ERV to the HVAC ductwork will they have to run the HVAC fan 24/7 or will the ERV be able to push/pull on its own when the HVAC is not running?
If you dump the fresh air into the return side then yes. If into the supply side then no.
Am I correct to assume that you are talking about a house with central AC/Heat? What about if you're using ductless cooling and heating, like a mini split?
Then this:
HVAC Reality Check: Are Duct Systems Dumb or Essential?
th-cam.com/video/5VPqFSITm0w/w-d-xo.html
wow, fantastic video. Thank you!
Carpet as I can’t imagine your ERV fan can overcome your duck systems static pressure if you are dumping your ERV supply into the return of your HVAC system you must be running the HVAC blower constantly isn’t that an issue with energy use and wearing out your blower?
Are there some climates where HRVs and ERVs aren't worth the extra install costs and running costs? In Auckalnd our summers are mild and winters not bad either so it doesn't seem cost effective here. Would you agree just a positive pressure ventilation system would be better in Auckland?
Not climate, but home characteristics- if your home is tight enough that bath exhaust fans will cause suction problems, you must have an ERV to exhaust from bathrooms and balance. If not tight enough for that, then stick with simpler means of getting fresh air.
Watch this:
th-cam.com/video/lnOCAPPVT5g/w-d-xo.htmlsi=yRBsI7JJ7y2h8Heu
@@HomePerformance ph, let me clarify. I mean ERV vs supply only systems. MY point is, I think in Auckland it's not worth the extra cost to try and recover heat from the exhaust air.
Again, I don’t even worry about the recovery aspect- to me, it’s all about the balanced pressure in the home.
I realize that I've been designing systems placing the supply and exhaust adjacent to each other on the same wall. is this going to cause short circuiting? ruh roh
We’re all always learning
I'm about to buy and rehab a 2000 sq ft 1960's pier and beam house in south texas. I will be replacing all duct work and HVAC system. HVAC is currently in a closet in a bedroom, with return in the hall. Would an ERV be worth it or should I just exhaust everything outside? I'm planning on installing a stand alone dehumidifier in either the attic or an aprilaire wall mounted one.
Do a blower door test- only way to know for sure
What are your thoughts on dumping ERV fresh air supply into AC supply with BD instead of return, not needing to run fan continuously?
Can work, just missing the extra filtration. Maybe best would be a Wye with an either/or damper.
When installing the fresh air supply output of the ERV in the HVAC air handler return path, does it matter where the air handler filer is? I would think that the common location of in the return grill will cause a significant low pressure situation when it is running, increasing as the filter fills up. I think some people have the filter at the blower motor, which is a different situation. Should those with a grill filter have a box added at the blower to accommodate a filter move? The simplified installations (retrofit) have both the fresh air supply output and the room air exhaust in the central air handler system. It seems to me 0.5 in wc would really mess with the ERV fans. Thoughts? I have looked at a couple of install manuals, but none of them have made a comment on that central filter location and its effect on performance and balancing.
Exactly, Larry- filter grilles are only for not using the return for anything else. Filter slot is so much more versatile. Also, 0.5 would be supply + return, so ideally you only have 0.1”wc in the return trunk.
@@HomePerformance I will check where and how large that pressure drop appears soon. I suspect that making the filter location change is in order. Being in the attic, makes it not such a fun chore to change the location by adding the filter box at the inlet. I have been also trying to decide if I can economically change the blower motor to be more efficient (EC or DC) such that i can run it at 1/2 speed in fan / heat mode with 1/8 the power while the ERV is active 25% to 100% of the time vs drawing 400W all day and making more noise than is desirable due to the air velocity being a bit higher than needed.
When these units say up to 75% efficiency is that only temperature transfer. How do we find a spec for humidity? I'm on the gulf coast and need ventilation but humidity is a huge issue already without it.
Only some manufacturers test for that, and probably not all of them list it if they're not happy with the results. Broan does, and Renewaire too I believe. You should spec a dehumidifier, I almost guarantee the ventilation will increase your home's humidity levels.
@@HomePerformance I already have both. Massive humidity issues... Working on iterating after 6 years of problems.
- Builder Install: Unfiltered passive intake into unfiltered air handlers. Filter back grills.
- Rev 1: Capped one wall penetration, UltraAire 120V ventilating dehu on the open intake ducted into air handlers, SantaFe Classic in Garage below home, five 70 pint retail dehumidifiers around house.
- Planned Rev 2: Dual UltraAire 70's and a Broan ai ERV all ducted into air handlers, SantaFe Classic in Garage below home.
Unfortunately at this point I'm stuck retrofitting for damage control. Targeting < 50%rh.
@@jongosling4870 check your building envelope with a blower door test.
Damn Jon, that sounds intense. I agree, blower door test might be in order.
@@HomePerformance "someone else's" blower door expert gave me a 5.
Very interesting ,thanks. Wouldn't there be a need for supply and exhaust in each bedroom and the office too?
YES, which is why I advocate ducting the fresh air into the return of the central air handler- it'll get there. Otherwise, a totally separate duct system is required to deliver it to each bedroom and office.
@@HomePerformance so, the returns from baths and closets get fed into ERV, fresh air from outside also gets fed into ERV... ERV transfers the energy (hot or cold) from baths and closets to fresh air from outside.. and this outside air, now with energy transferred to it gets fed as the return to the home HVAC system..... Will the HVAC be able to appreciate/ detect the return air temp and adjust itself ?
@@jimmyphilip2340 I wouldn't think so. Maybe some types.
@@jimmyphilip2340 No. The frest air is tempered and mixing with the room temp air circulating in the return duct. The blended air will eventually change the temperature at the thermostat.
Use an air mixing cslculator online to see how little impact it has.
Where do the supply vents go?
Sounds like he's recommending piping all supply into HVAC return before filter
Great video. Do you add exhaust vents to the Kitchen area?
Always need an exhaust hood going outdoors over the cooktop
@@HomePerformance Yes, agree. Do you recommend both an ERV return and supply in a large open kitchen/great room?
@TheGhussey neither at my house, unneeded- but there are no wrong answers
Why are there no exhaust vents in the bedrooms and office?
They’re positive pressure zones, which encourages circulation between rooms.
I always assumed exhausts were not over the shower to avoid being wet.
Can someone explain to me (cause I am not familiar with the technology): why can’t we simply open the windows once in the while?
We seem to be approaching the end stage of overly complex societies. Shouldn't be long, before we are back to radio communications and out houses.
Another great video !
Thanks
In your example you put an exhaust in the washer/dryer room, but you said that you would not actually recommend putting one in that room. Why not? I’m just looking for additional information and not disagreeing with you.
Do you smoke crack in your house? How well does erv filterate the smoke?
Erv, being porous, might reintroduce Crack back into the house, along with bathroom farts.
This is about energy recovery- I think you’re looking for the channel on crack recovery.
Where do you get your cfm exhaust per room number from
Int’l Mech Code. 20 cfm for bathrooms.
Why wouldn't you want fresh air put into bedrooms/great room?
Yes, sure- don’t think I said otherwise in the vid
Where are the intakes?
If you dump the ERV output into the HVAC return, do you have to run the HVAC fan continuously?
If you want continuous fresh air, then, yes.
Yes you do, Fred- otherwise it won’t go through the filter, get mixed and conditioned, and get distributed through the supply ducts. It’d just turn the other direction and follow the path of least resistance out through the return grille.
@@HomePerformance Thanks for the timely response. That's what I expected, just being sure.
@@HomePerformance but if you had one way dampers fitted they would close when the hvac was off and air would be forced to go the correct way, or would that put to much restriction on it?
A one-way damper on a return would be massive, and for sure would increase your static pressure.
I think it is a mistake not to have an exhaust for kitchen. Cooking produces lot of humidity and various smells.
You have a dedicated exhaust hood dumping outside, use that
But this way you make a messy disbalance of in/out volumes. Will not work in tight envelope houses. Good extraction hood can do hourly cfm of an erv/hrv in few minutes. And in cold climates this will not work, might freeze the unit as it sucks a lot of cold air and there is no exhaust to warm it.
Better to do extraction hood with carbon filters, that dumps air back in the house and have erv/hrv exhaust in kitchen. Well at least thats how we do it Europe.
you are loning for make up air
Why are you putting a fan over the toilet in the primary BR?
Because the fan over the shower won’t pull odors from the toilet effectively.
@@HomePerformance got it. Thought it was for removing additional steam/vapor, but purely for odors, not necessarily required
Also, if you use the Broan AI to dump into your return, does the "AI" still work? Or do you need to manually adjust?
ERV stands for ???
Great video on erv but my question is who has vent covers for smell duct looked all over and can’t find anything
Fantech MGE4 and MGS4
What about the kitchen hood. You don't figure that in?
Nope, always separate. That will need its own make up air:
th-cam.com/video/CSmwDGxtlHU/w-d-xo.html
Just to clarify for my dumb ass: all those exhausts go through the ERV, right?
Haha you got it right buddy
So if I have an ERV to exhaust, do I need to have "fart fans" in the bathrooms?
No, in my view it’s one or the other
Title says where to place exhaust and supply. What about supply?
Yep, it’s stated in the bid. Dump it into HVAC system or duct to bedrooms.
won't it really depends in what part of the world one actually live? isn't all about the environment ones house is placed?
an HRV is a better choice if you often have an overly humid house during winter, while an ERV is superior if your house is too dry...
Overly humid house during winter with any ventilation system running is very unlikely- sounds like something is wrong in that case