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: kzfaq.info/get/bejne/gs-gp9aSsNPVaGQ.htmlsi=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

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

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!

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

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.

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

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.

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 !

Fantastic. Great useful information. Thank you. Cheers J

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 :)

Thank you for this wonderful news! :-) Great inspiration! ... And I like your humor! ... lol

Great job!! You SHOULD be proud of it. it looks NO different than the expensive Panasonic one. Thank you for the inspiration!!

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

Very nice! Hope you have other projects to show off as I just subscribed to your channel.

Man I'm absolutely blown away. You did an amazing job. Well done on your research and execution. I have a whole new view on heat recovery systems now. In HVAC, these items are extremely expensive. I don't often get to specify these due to clients not having the budget for it. After seeing your results though, I think I can come up with something affordable and efficient on a commercial scale. I feel efficiency can be improved with a quick material study. Thanks for your video. I'm very impressed and appreciative for you helping me see how simple this system can really be.

This is exactly what I was looking for. 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 really cool!!

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.

Nicely done!!

You are the KZfaq MVP on this subject💪🏻

Nicely done! Corbett mentioned this video in a video he uploaded today.

this is so rad!

Very nice. Now I want to build an ERV

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

Impressive!

Yeah, you earned my subscription. Looking forward to more of your content.

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

Well done.

Awesome! You inspired me to build one. I’ll try brazing aluminum flashing for better conduction.

Dude. You’re an awesome enthusiastic presenter of your creations. I’m thinking of something like this for my large garage. Maybe not quite this big tho

I applaud the initiative. This is certainly the future & I love it. Some things to consider... 1) CO2 "cannot" be affected by the unit, as the CO2 level is whatever you are drawing out of the air coming in from outside (usually about 400 unless something weird is going on. Plants like it when we "talk to them" because we are breathing CO2 at them. CO2 builds up in a house because of "us". 2) I would be greatly concerned about the VOCs coming off all that plastic, adhesive and other chemicals from 3-D printing. It's gonna off-gas, a LOT! Funny your comment, "insane!", right after, cause..., yeh. 3) There is an actual Metric they use, CFM/watt, to quantify how much actual work is being done. It's used to measure performance. Measuring the Factual temps of the airstreams is of great interest also. 4) Tape the edges of the filters or there is bypass (sneaking around the filtration, around corners). HEPA has no "bypass". 5) Measuring the air pressures will tell you the static resistance various parts of the system are causing - core, filters, vents. Cool experiment, but don't mislead people with hyperbole instead of data. Maintain integrity. Do no harm. Cheers.

you can make it more "compact" just by placing the vents from the outside in the bottom and the vent inside on the top. then it would cover the window, but at least you'll have floor space. the trubulance from the air turning 90 degrees twice might aid in the heat transfer

Very cool. I’d love to see a full build video with parts and dimensions. I’m already wondering if I could fit this in the top of my entry closet. It’d require drilling holes in my exterior wall and the closet wall, but it’d solve the obstruction and looks issues here. Also curious to see the process of changing the filters. If you have to open the top for maintenance then this install location might not work (though I guess you could put it on the floor of the closet instead).

You probably want to insulate the intake and exhaust pipes on the outside end of the HRV - those have cold (in winter)/hot (in summer) air that is going to lead to undesirable heat transfer to your indoor air.

This is cool content. Subscribed.

Great video, meticulously. explained and delivered. I subscribed and wish you luck. I mainly open a window for fresh air, but a fully running unit would be beneficial no doubt. Btw, those “idiots” you refer to that put pesticides on their lawn probably don’t watch these types of videos!

Freaking love this. Instant sub

Excellent !! Thanks !!

Love it, considering buiilding one of these for my home too! You could have used half the correx by using double sided foam tape to create the core, with one channel being formed by taping two sheets together. (using tape with a thickness similar to the height of the plastic sheets) this has the advantage of also reducing the thickness of plastic seperating the air channels, so heat transfer should be more efficient. (as it would be one layer of plastic rather than two layers plus glue) Also a dual core design could improve efficeny by doubling the surface area for heat transfer.

Great job! I've seen a similar design on "build it solar" website before, but good to actually see a working prototype. One question: do you get condensation inside your core? Some HRV design includes a heating element to combat the condensation.

This is great! I wake up every morning and my bedroom smells like crap.. Sinuses and nose at winter are always kinda gunked up ... Every time i get ill in the winter months is always the same symptoms, sinuses , nose and throat full of awful fluids that i have to spit out.....I think all the bad fluids wanting to go out from our lungs and throat is way of our body to clear and flush all that crap out.. Im 100% sure that air quality plays a massive role in that respiratory system. I dont mind opening window for a fresh air multiple times a day but at winter its kind of waste energy and also when it gets cold outside air is crap to! Cause here in Serbia a good bunch of houses still uses wood and coal to heat their homes... here the market is so terrbile that small home HRV's are basicly non existant and the big comercial stuff is to expensive.. Your build rly goot me thinking, looks simple to make and i could put it on my attic and duct it down in the house like a cealing vent. Curious to see whats next .. Would like to see how you tested efficiency , what was the indoor temp and intake temp of the fresh air and stuff like that. Greets from Serbia.

This is amazing. I now think my son should have this in the little room he sleeps in with the door closed all night. He'd be freezing with the window always open, but he has allergies and could use the filter. Plus I can imagine that CO2 levels rise in a tightly-sealed, unventilated small room with someone breathing all night. Hmm. You have me really thinking. I need to get your recommendations for the right instruments to measure air quality. Oh, and you really are sounding less allergic. Nice!

I'm looking into this myself as I'm struggling with keeping the cat litter smell at bay now that I have two cats, and great to see that this design with the plastic actually works well. I would have figured it would not have enough thermal conductivity. I might have to experiment with this and see if it will help. Right now I'm just opening the windows but that won't exactly be an option in the dead of winter!

Great video, could you please go into detail about how you made the Coroplast Square core? Thx for sharing your videos

Great design bro! This should work damn well for your money! As an engineer, I am pleased to hear competent technical reasoning accompanied by such a simple but ingenious design.Bravo. Physics does not work on the loud brand and price of equipment, but on the principle. You inspired me not only to make a similar device for myself, but also to think about the serial creation of cheaper systems.Where I live, such systems are not financially available at all. Everyone deserves to breathe clean air.

You have all reasons to be proud. Subsribing.

Very cool to see the concept in action. If the plastic transfers heat so well, wouldn't you need another material to insulate the connection to the window?

Good job

Thank you for sharing this, truly. Definitely a thumbs up! Sharing knowledge and experience like this this is the internet at its best. Also nice to give credit to your sources at the end. Question 1: High effective is 85% as compared to a commercial system? I could do my own research of course but in case somebody knows already ... Question 2: Did you consider alternatives to spray adhesive for laminating the plastic heat exchanger stack? I am thinking it is an unnecessary source of VOC’s? Are there “healthier” adhesive options or am I being overly concerned? Question 3: Would efficiency increase with a heat exchange filter material of greater thermal conductivity like copper or aluminum? A am pretty sure moisture build up would be an issue if installed “properly” with outgoing air coming from high air moisture areas like bathroom, kitchen and laundry rooms however. But in any case really cool build!

Thanks for this!! I’d like to try and build one and was wondering if you published your sketch up design?

Cool.

Hi, what a great job - well done! I may have to put one in my home. Would you do a design drawings for my house size layout if you could?

Thanks for this video! I think that you could make that box into a vertical version if you used plywood for the largest sides. It would not need to be more than 3/8" thick to support that core. Probably 3/16" would do. I bet masonite or "bath-board" (which has a nice finish on one side) would work very well. Adding some 1/2"x1/2" wood pieces in certain corners to further stiffen the housing would help as well. (even if using your current materials for the walls) I think that you might get more efficient airflow if you used some internal ducting to reduce turbulence between the air inlets and the filters and the air outlets and the core. (The shape of the chambers the air passes through is probably causing a lot of turbulence) A piece of thin poster board could be formed into a cone that is the diameter of the inlet at one end. The other end could be creased into a square to fit the filter or core. (the circumference of the filter/core end should be equal to or slightly larger than the perimeter of the filter/core in order to fit) That would give you a custom duct for very little in the way of expense and effort. Another good material for this would be a used printing-press plate. They are usually aluminium and can be gotten at any place that prints posters etc on a lithographic press. A layer of radiant-barrier material (like ArmaFoil from EnergyEfficientSolutions d0t c0m) over the block in the window and on the inside of the walls of the housing of the HRV would insulate the system and increase the efficiency a little more without adding much bulk or weight. You could also make the core out of the lithographic plates I mentioned above. Just cut out a rectangle whose long side is longer than the short side by twice the distance you want between plates. Then fold the edges of each of the short sides down by the distance you want between plates; so the profile is like a very wide staple or 'u' shape.(if you cut them out and folded them right; they should be square now) Then you stack them alternating the sides that are closed by taping the folded edges to the unfolded edges on the next plate. You could use hvac foil tape for this to get maximum efficiency. This setup has three advantages over the current core design: The first is that aluminium transfers heat much more efficiently than plastic. The second is that the single layer walls would be more efficient. The third is that there would be better airflow through the core because of the undivided center of each layer. (A tip for cutting lithographic plates is to use an xacto knife and a straight edge. You do not need to cut all the way through. Just score it well and then bend it at the score lines and it will snap)

The stale air only needs a dust filter to keep the core clean, not a m13

Well-Done

Nice build. Anyway next time consider brushless centrifugal fans and also damper to allow the unit work in "circulation mode", in mine, is also built-in cheap AC unit, so mu unit can also cool and heat...

"Never cross the streams." Dr. Egon Spengler

Really nice work. You've mentioned your HRV's size, (07:56), which got me thinking.... the ducts, fans, filters, and heat exchanger must stay about the same size to meet your needs, but eliminating everything except for those essential parts, should reduce its size by at least half, maybe more. Alternatively, installing your HRV out of sight, like outside, or in the attic, should leave only the intake and output duct holes visible inside the house. Good luck, and thank you for sharing.

Great project, even if the efficiency did not quite measure up. I would argue however that anybody building one to install in an older home should dive deep into already existing air infiltration issues. Just a few poorly sealed holes in the framing can cause a hidden issue through the entire home, even through interior walls over crawlspace construction. The pocket hole doors originally built into my home permitted an absolute blast of air through them when the house was pressurized, much of it likely coming from the crawlspace. (I sealed the pocket doors in entirely.) Even the catch on the jamb for a door latch became an obvious breach that a little caulk easily fixed.

I Would like to see how adding thermal paste in-between the panels would perform...nice video

It would so nice to recover moisture also!

Great work! I'd place in the attic or at least that is what I planned to do with mine. I assume you saw the Hackaday HRV and maybe also my comments there and his youtube videos. I bought a few rolls, and even got some for free, of aluminum window screen. The thought was at some time 3D printing or maybe CNC in wood a tool and die to stamp like a linear ridge zig zag stamp so to increase the surface area of the alternating layers. I also found an old hair iron crip wave thing that is close, though small. I plan to only space the one path of flow and use corrugate on the other path. The spaced path that would use two other maybe three strip of one width corrugate tubes would have the zig zag aluminum mesh. I left off wondering how to plastic weld both sides into the full sheet of corrugate. The other thought was just ironing into both side of the corrugate the aluminum screen. That might work suitable as well and just then placing the zig zag screen into contact. I probably should work on again since I have now another size of corrugate material, 4mm, and not only the cutout 12x12 inch larger thickness 10mm corrugate. What thickness corrugate did you use? Thanks for sharing. Great to see more of these designs being made successfully and cost effectively.

Condensation within the unit will be a problem in most climates and when heating or cooling the incoming air. Over time the heat transfer plates will grow a biomass that can (in extreme cases) include dear old Legionella - the bane of commercial air con units. So a unit will need a means to drain condensate to a waste, and a way to periodically (say annually) disinfect / clean the core.

Impressive and inspiring, thank you. For someone interested in trying this, why coroplast, other than it comes pre-corrugated for maximum surface area? Wouldn't metal plates work better at transferring heat? (but much more time-consuming to pleat by hand). Maybe the fins from old A/C and HVAC equipment can be repurposed for this. Amazing effort and spirit, blessings and apprecation.

I am so making a MEME from you saying “absolutely”!

Great vid. Thanks. Do you know how many cfm this unit moves?

A build video would be interesting. If you feel like building another one, I'd appreciate that.

Good work! What would you recommend for a camper van or RV? Just filtered intake and crank the furnace?

A heat exchanger on the window side output would extract the last bit of heat. It is an energy expense, but heat exchange is more efficient than conventional heating.

I have an existing HRV that is starting to show it's age (getting noisy) and replacing the fans would be something like 1200-1500€ so I am thinking about getting a new one. Doing some DIY work on it with third party fans is something I have been thinking about, but the original fans are custom built and I have been unable to find duct fans that I can properly control. The originals are radial fans and built specifically for the HRV...

Mitsubishi sell these. They are called lossnay units. Reasonable instantaneous efficiency results, for more reliable figures use loggers and gather more data points at changing operating conditions.

It would be nice to see examples of external house wall holes that pass permit inspection. Hole covering would include everything needed to simply unplug whatever DIY HRV solution you have in place to easily sell your home.

Can you repurpose UFH components to use in a ceiling for cooling, hooked up to a heat dump somewhere?

It would be pretty easy to make that design with slight alterations self-standing on the floor and to act as a window shelf.

The Panasonic NanoeX does an excellent job of reducing VOCs, if you can get your hands on one.

Filtering the fresh air isn't a bad idea. I apply herbicides all day, but stop near evening because of the inversions carrying the product to unwanted places. I live near the field and wouldn't mind having something like this. Pretty big though.

Chloroplast may work, and you appear to have built this one sufficently large to get fairly good efficency at the rate of air exchange. But, know this. Plastic is inefficientl at moving heat across a given surface area. Your heat exchanger could get comparable efficency with a smaller design if the core were made of sheets of aluminum seperated by small three or four spacers each layer. Or you could achieve significantly higher efficency with an aluminum core built to to your existing core size.

Now add a solar preheater to the inlet and crank that efficiency up.

Hey mate, that's already on my diy project list, I am evaluating different materials for the heat exchange unit and currently the best choice from my point of view is aluminum as it has the best heat transfer rate and is already available as foil. That should bring the efficiency somewhere around 95%...what's your opinion? I was very happy if you could provide some statistics about the air quality over time with switched off device and running in different power modes like e.g. being alone in contrast to many party people, cheers and stay healthy 🍻

A low tech "defrost mode" method is to just redirect the two outdoor ports together so the core warms up to room temperature eventually. By measuring the output temperature and only going into defrost mode when the output goes below freezing can make it automatic.

That's an interesting design. I've actually seen a very similar design (using coroplast) from an HVAC company that fleeced me thousands of dollars some years ago for an HVAC design that included one of their custom ERVs. I got suspicious after seeing that they didn't have a test in HVI database, and after seeing the docs that they sent me, it literally showed 0% humidity recovery for their "ERV". Which made sense, since this type of design is non permeable and cannot recover humidity, making it an HRV only solution. Didn't have the time nor energy to try and get my money back.

Well done and nice and cheap. I well remember last century, pre internet, someone had constructed a very efficient HR unit out of pleated paper! Large pieces of paper, folded about every half inch or centimeter and laid cross ways like your core flute and connected just the same as yours. The paper being thin, had excellent heat transfer properties and low impedance to air flow. Question would be, how would it go in high humidity? Maybe spraying with a mixture of something non toxic but hydrophobic would be the answer. Plant wax? I'd say your set up would suffer losses because if the poor heat transfer of the double layers of coreflute. I have seen single sided stuff around. That would improve efficiency. Maybe single sided corrugated cardboard would be the go?

PS: for heat recovery and fans, I decicded to go with commercial solution which was in just about 600€, so I added only control, dampers for circulation mode and AC unit for cooling and heating😂

If you're chasing every last % of efficiency you could make your own fine channel aluminum heat exchange core. Get two or three Fiskars 9340 paper crimpers with metal crimp rollers. The rollers are the parts you'll want, to put together end to end on a common shaft because they're only 6.5" long. Might need to double up on the crimpers if only one roller in them is aluminum. You'd have to build a custom frame to hold them and add a long hand crank. For metal, whatever thickness is used for offset printing plates would probably be ideal for the corrugated channel sheets. To separate the corrugated sheets use heavy foil, the thickness used for single use turkey roasting pans ought to do. I'd expect thinner to be better for heat transfer. Can't go too thin on the corrugated sheets gauge because the core would need rigid plates on the sides and a way to compress it to ensure good contact between the corrugated and flat sheets to block bleeding of air between in and out paths. It would have to be more efficient with heat only having to cross one very thin, highly heat conductive sheet of heavy aluminum foil VS two layers of plastic that don't transfer heat anywhere near as well as aluminum. Any bet it'd be over 90% efficient at heat transfer? Fiskars makes a wavy version of the crimper, model 9341. Wavy channels would make the air slower, with a longer path through the core, but those crimpers look like the crimp rollers are all plastic.

Good job, how much the fan motor consume power and where did you buy them

Nice design! How do you get fresh outdoor air without ducts using a fan?

U have a 14*14*14 heat exchanger made of coroplast , what should be the size of the heat exchanger should be if i where building with aluminium or copper foils

Clever to recognize coroplast as a useful material! Its thermal conductivity would suck compared to metal, but if the dwell time of the air inside then heat exchanger is long enough, that will compensate: Half the conductivity? Just double the dwell time. 1/4 => 4x, etc, etc. It seems the duct fans are working fine for you, but a cheaper and potentially better solution could be a used squirrel-cage blower from an HVAC system, with the speed adjusted via either a cheap A/C speed controller (triad plus noise filter) or by putting a small motor on it, running it via a timing-belt setup (the kind of timing belts used for 3D printers. Squirrel cage blowers are great when dealing with back-pressure from filters or the stack itself.

any reason the exhaust channel is getting air pushed instead of pulled like an exhaust fan?

Cool, consider to separate the outside in and out to ensure you don't mix the out air with the in one!

I’ve got a room I use for 3d printing. Resin and filament. I’ve been doing research and I think the fastest way to have better air is to replace it rather that strictly filtering the air. Do you think a system like this would be a good use for a room like this? Ultimately I would like to have air intake going through the wall rather than through a window. Also does the height matter? Like would having it lower work better than having it higher closer to the ceiling? Would be so awesome if I could get a response.

8:52 Condensation needs much less air movement. You always deliver fresh energy, to evaporate the condensate. This is a great factor for efficiency at large temperature differences, but what can you do🤗

Seriously though, well done you.

I think the main thing stopping you from having better efficiency is the cross-flow. Your two airflows are perpendicular to each other, and you can get better heat transfer by having contraflow instead, where the airflows are in opposite directions. However, that makes construction slightly more tricky, and probably can't be done with the materials you are using, as the airflow needs to change direction in the middle of the core, and the core needs to be longer to have that contraflow section in the middle. I'm considering making a unit with (very cheap) aluminium foil, but I'm not 100% sure it is durable enough.