I built the best DIY heat recovery ventilator I’ve seen on YouTube

IMPORTANT UPDATE: I did some more efficiency tests in the spring using the outgoing air and it seems that my HRV is actually around 60% efficient (which is still pretty good), not 85%. I wanted to make a video about this but I ended up having to put it on the back burner because I went through the process of selling my house. When making this video, I made the mistake of testing efficiency using the incoming fresh air. I think that heat generated by the fans skewed the results. Here’s a formula I used for a corrected efficiency test using the outgoing air instead: × = (T_room - T_outgoingAir) / (T_room - _outdoors) An example of one of my test runs (Fahrenheit): 60.5%=(70-44)/(70-27) So yeah, it is less efficient than I initially thought. That being said, it still worked quite well. I want to address some questions I’ve seen: I do think that almost all of the air is flowing through the core. The filters were quite dirty when I dismantled this HRV, and in order for them to have gotten like that, I do believe air must have passed through them/the core. I don’t think there is very much leakage in the chambers. I sealed them very thoroughly with hot glue and weather stripping, and did leakage tests. I acknowledge that there could be some leakage, but not that I could find. Next point, to the couple people who quoted Egon Spengler at me: no, I don’t believe I’m “crossing the streams” (intake/exhaust air streams mixing). After this video came out, I installed elbow duct attachments to the indoor supply and outdoor exhaust to the direct the air streams away from the intakes 🙂 Potential reasons I didn’t run into condensation issues: lower HRV efficiency combined with the low dew points in my house (from ventilation with dry, cold air + no humidification). I only used this HRV during the late fall, winter, and early spring when the air is very dry. I’m too worried about mold growth when it gets humid. Though less efficient than I initially thought, it still worked great! If you're curious about how this DIY HRV performed long-term, check out this video of mine: https://youtu.be/LiptsaKmq80?si=bsEbBQ9pKLKozY4u

As an HVAC guy i can say your design although unconventional and bulky is just fine, your fans you use for circulation would benefit from the coandâ effect to increase air flow. Also those efficiency rating the big companies use are totally skewed so your system is probably working better than off the shelf systems thanks to that massive core you built

Bro, you would put a little greenhouse lean-to against a southern wall of the house outside the window to actually heat your house on sunny winter days. Also, you could just skip the return fan and suck air in and make your house “positive pressure so that you leak a little air outside rather than allowing dirty air from outside to find its way into the house

Dude you are brilliant, it never would have occurred to me to use the natural tunnels inside of coroplast board! That's legit mate. You've managed to achieve very near the efficiency of commercial units that cost thousands of dollars. This is such a great idea, you've given me all kinds of ideas for my own apartment.

Definitely going to do this now, didn’t know that the diy actually worked so well and with testing to back it up! Thats all I needed! This will definitely help with my parents cold basement and spare second story room if I hooked it up to the previous improperly installed furnace air return. Thanks

To improve upon your design ; if you suck the air close to the floor in your basement you'll also get Radon out of your home. Intake/exhaust on each side should be seperated by about 6feet. You could install a ceiling fan instead of the box fan that on the chair. Great work!

This is unbelievably cool, even with the potentially lower efficiency number. I just bought a house and have a 1990s furnace that I want to keep running as long as possible. Currently in the process of cleaning and sealing the duct system and trying to DIY as much as possible. The furnace uses a long insulated flex duct to allow unfiltered cold Canadian air into the furnace room for combustion. I feel it’s very inefficient (and dirty) to have a clear line of outdoor air entering my home. Your system seems like the perfect DIY method to address this problem. Just found your channel and looking forward to seeing what other ideas you have.

Stunningly simple, cheap and effective. Well done man!

Keep it up. Love the facts and your delivery.

Subscribed man. I'm not sure how I've come by your channel, but I am very grateful and have learned so much. Thank you for taking the time to post!

as an actual HVAC Technician i think that is pretty neat. the physics is the right way around and from the numbers i can tell it works. the only way to improve would be a more conductive material to get the usual 90-98% efficiency but apparently its conductive enough.

If your HRV actually is 85% efficient you should get a lot of condensation when outdoor temperature is below freezing. You can figure out the dew point of your indoor air, and unless that is as low or lower than the expected temperature of the exhaust air there should be condensation. The "fresh air" you get is definitely a mix of fresh air and indoor air that leaked into the fresh air stream, possibly not in the core, but definitely in the giga-supersized chambers outside the core. Also you need to make sure the flows doesn't mix outside to get an measurement of the actual efficiency. If you measure the temperature that leaves the house, on the outside, instead of the mixed airflow, and compare that to indoor and outdoor temperatures you can find out the actual efficiency. The actual efficiency is definitely not anywhere near 85%. Aluminium conducts heat around a thousand times better than most plastics, and you can make aluminium much thinner, which also improves heat transfer compared to plastics. You even have two layers of plastic, and a layer of adhesive, and possibly areas with air too. And no way those fans can force hundreds of CFM through that core, a powerful leaf blower might be able to do that.

Thanks That's a really good design. I've been thinking about how to build something like this for our home. I'd not considering using coroplast, but it's almost made for the job !

Excellent video. Really good build quality and very well explained.

Wow! Your did great! You did a great job! And so efficient too! I live in a very small home in CT, a 200 yr old home, I renovated 20 yrs ago. Our home is 24x22, with basement, 1st flr, 2nd flr, and walk up attic. It's a post and beam kinda house. I installed ductwork, and Air handlers, one in the attic to service the 2nd flr, and one in basement to service the 1st flr. I have a boiler for heat, so it is a hydronic system. Each AHU has a hot water coil, that way I can also temper the discharge temp. So I think about 5 yrs ago, I added a Fan tech ERV to my 2nd flr setup. I added external filter boxes, with I think Merv 12 filters it came with, cause you need to keep that core clean as well as the air we are gonna be breathing. This was the lowest price unit at the time, and the enthalpy core is same product you used, but not as nice as yours, mine is not very efficient, so on really cold days, I don't use it. But a year later I bought a HRV for the basement I spent a little more and got one a bit more efficient. [I'm not rolling in $] I have seen some really high efficient EVR's but big $. I'm fortunate I inject the "make up" air into my air handling system. I also have UV-C lights in the AHU's. I have my 2nd floor ERV set up so when I run it, a relay turns on the FAN mode on my t-stat, so the AHU is running to distribute the air when the ERV runs. I have a Timer so 2nd floor runs at night [bedrooms all on 2nd flr] but also another timer called an Air cycler. This means it will run say from 6pm to 8am, but the air cycler runs the system 15 mins every hour. Then if someone hits the Exh fan switch for the bathroom, it turns on. [The stale exhaust air, get sucked out through the bathroom registers]. Anyway the results are great! I eventually will improve the ERV with a more efficient one in the future. The indoor air can be so bad, plus I'm try to learn about "static" pressure in the house. So when I turn on the range hood on highest setting 600cfm, where the make up air? or air coming in? Do we pull a negative pressure bringing in more bad stuff through the chimney?? Or cracks around the doors?? So an intentional conditioned make up air system is so important, especially weather when you cannot open windows. So thank you for sharing your project! So cool! [sorry to be so long winded here, but I get excited about this stuff! ] God bless! AL from CT

i love this!! thanks soo much for sharing your creation and findings! soo helpful :)

i built one in spokane in 85, using plastic sheeting and bathroom exhaust fans. i like your design.

Fantastic. Great useful information. Thank you. Cheers J

Wow! Excellent job, I'm definitely going to build something similar

Such a great design! I may build something like it for my place. Wonderul.