DIY Heat Recovery Ventilators for 50$. How HRV Works.

[@corlfranco9371]

Use solid state switching: triac or mosfet or transistor (reduces relay noise). Use a polarity reverse on both fans instead of switching between one or the other (to use 2 fans always instead of just one or the other at once). Add a pause at the switch event so the fans dont fight each other during free coaster transition (to reduce transitive state inneficiency )

[@darkshadowsx5949]

you cant polarity reverse these fans. they have circuitry to limit spin in one direction. plus the blades arent design for that. i do agree he should use an SSR instead of a mechanical relay. they can be quite compact. i have some that are 4-DIP single relay and 8-DIP double relay.

[@martas414]

@@darkshadowsx5949 isn't it necessary to reverse the fans? After all, they are located opposite each other, so one sucks out and the other sucks in!! - I'm talking about the version with two fans.

[@donalain69]

I build a comparable system 10 years ago. But used a self-made conventional heat exchanger (the square box with a diagonal orientated square radiator in it type). All you need to build it is a cheap roll of aluminium sheet. Installed a strong fan to blow the air in on one side of the celing of the balcony, added a stainless mesh, carbon and HEPA air filter in front of it, and cut an outlet vent oopening on the other side of the balcony. next just cut an inlet and an outlet with a bathroom exhaust vent in every room, connect it all of it with duct pipes in the celing and its done. Has cost me less than 50$ per room.. and you get a constant airflow. the only problem is regularly changing the hepa filter and water accumulating in the pipes.

[@klausbrinck2137]

one-way-Heat-Recovery-Ventilators work by storing heat. You did the opposite, by using aluminium (or any metal for that matter, but aluminium is surely the worst bet of all cheap metals). Spend additional 150$ and get the real deal with a ceramic core. If your wall is thick enough, get 2 ceramic cores, and set them up in series. That will raise efficiency from 90% to over 98%, like in the big centralized Heat Recovery Ventilation systems (for a fraction of the material/installation-cost, and space-demand). And if your wall isn´t as thick as 2-core-lengths, let the tube stick out of the wall, cause it´s still 100% worth it...

[@willb1242]

Looks to me like his second design uses aluminum as an exchange medium separating two flows, not as thermal storage. So aluminum works great, in fact, it would work better if it were thinner. The fact his outdoor in/out temps are within 1 degree shows how well it is working.

[@klausbrinck2137]

@@willb1242 The 2 flows you assume, they happen termorally separate, sequencial, and not simultaneously... Such HRV always need a heat-storing-medium, that´s of ceramic nature, and costs around 450€ in Germany. During winter, while one of those blows cold fresh air into the house, thereby cooling the HRV, a 2nd one, in the outer wall at the opposite side of the house, expels dirty warm interior air, thereby heating the ceramic up. And the test he made, is of no scientific relevance, that is far too crude, to make any ssumptions from it. The disadvantage I see, compared to a much more expensive centralized HRV-system, is the low HR-efficiency of just 90%, compared to 98% of the expensive central system(THOSE work with 2 separated flows, crossing each other, but not the HRV of this video). If one combines 2 ceramic-cores in series, that should make for 90% + 90%*10% = 99%, or a bit less (more electricity needed to compensate for the pumping-loses of pushing air through the double-core-length now), thus competing one-to-one with the expensive systems. But then, this previously short HRV would now be nearly double the length, protruding out of your houses walls by a bit (to the inside or to the outside, according to your liking), a purely aesthetical problem to my eyes. But that´s why those double-length-HRV don´t exist in the market. .

[@Daniel_Official_10]

​@@klausbrinck2137you didn't understand at all. His second version has 2 separated flows crossing each other. Watch again

[@Mchacz8008]

Aluminium is literally one of the best heat conductors, and has a very high heat capacity, and is arguably better than ceramic for heat storage

[@klausbrinck2137]

@@Mchacz8008 but for this application, you don´t need a good conductor, but on the opposite, a very, very mediocre conductor... at the same time, Alu being a good conductor, means, that it´s especially bad at storing heat (what sort of good conductor would it be, if it´d store heat, instead of immediately giving it up/further???). I tell all that, because the industry building the same thing as you did, says: Ceramic: good. Alu: very bad. And it also costs 400-500€ (surely more by now), so I hoped, you have a cheaper solution. But you don´t.

[@ivelinbanchev4337]

That's impressive! Considering the cost of recuperators these days, this could be an excellent alternative. Keep up the good work!

[@SeaScoutDan]

Need to have 2 of these tubes. What goes out, has to come in from somewhere.

[@jsjs6751]

Underrated comment. The first design is less than 50% efficient. Need two units running in opposite phase. While one is blowing air out, the other must blow in. Then, let that run for a minute or so, and then reverse the flow. Repeat.

[@renanfp]

Thanks for this english version! Like your work!

[@dominictarrsailing]

what about if the inside and outside air has different humidity? is there a way for water to escape?

[@specialblorb]

Thanks! I was planning something similar but with peltier / thermoelectric device to act as a heat pump between the outgoing hot air and incoming cold air. Oh, I agree with the other comment that commercial units seem incredibly expensive for what they are!

[@darkshadowsx5949]

TEC's are also wildly inefficient. 10-15% great way to waste power. in other words 85-90% of the power used is wasted. you would be better off getting a mini split AC/heat pump. unless you just love wasting electricity.

[@johnnymaker-j4v]

great and thanks for measuring. could heat transfer and heat exchanger efficiency be increased by placing stainless steel wool in the warm air ducts? stainless steel wool because it gets along with all metals without corrosion.

[@danielseddon3177]

Brilliant. I was looking at the price of these online and thought it was an excellent 3D printing challenge. I was thinking of something along similar lines to yours, but you answered some of the thoughts I was having.

[@anonanonkiewicz1921]

Important note: if your fan says it moves 100 units od air per unit of timer, it's possible that it will move just 10, if you coinstrain the airflow.

[@Netherlands031]

yeah, sometimes fans have a diagram showing air flow vs the resistance they're pushing against, that can help a lot with picking the right fan

[@dsgg5714]

Only 7 minutes? Please do more! It was very interesting to watch, and even motivates to do something likewise. Nice job! :) Is there any update video?

[@markthomasson5077]

70 seconds

[@eklhaft4531]

@@markthomasson5077 he means the duration of the video not the fan cycle 😁

[@ndqcuong]

awesome work, just bought a Daikin HRV for $300 on fb

[@eklhaft4531]

The noise is usually measured at a certain distance. Usually 1 meter.

[@PeterHertel]

Very interesting. Thank you for sharing. I'm in need of continuous fresh air in my basement and I'll try to print your version. All the best.

[@DIYYARI]

Thank you. This version is more efficient kzbin.info/www/bejne/fIbLp6ieftmLaZI

[@joyrideyt3037]

Hi there What is the name of that priting device creating the the white model? Thanks

[@pulporock]

An excellent little video, very clever. Cheers from Oz

[@thegeneraljoe67]

SERIOUSLY DUDE - YOUR A DAMN GENIUS

[@karlbekker777]

Waaaaay above my pay grade. Love it.

[@petergoestohollywood382]

This is probably the cheapest you’re going to get. If you cannot afford this, get a job.

[@webstella]

@@petergoestohollywood382 The expression "above my pay grade" refers to skill level not wage level.

[@DavideArzarello]

Can you provide the CAD file in a more standard format like STP / STEP, I'm not able to import/convert the Compas 3D format

[@rifkyramadhan6889]

Thanks you for sharing. Low energy can cooling room or heating room

[@maximthemagnificent]

Once saw a suggestion that one could make a heat recovery ventilator from disposable aluminum turkey pans. Stack them with spacers that block every other side to create the two separate airflow paths. Those pans are very inexpensive.

[@willb1242]

I made a ventilator with nothing more than a three inch aluminum dryer duct inside a cardboard box. The flow inside the duct goes out, outside the duct goes in. The vent is ridged for extra exchange area. It was a bit science project-y but it works so great I’ve ended up using it for years. The complexities come not with the basic idea, but when you add secondary requirements like it has to operate 24/7/365 with an owner who never wants to think about moisture accumulation.

[@WIZ56575]

I am very interested and on how you set up the fans to switch back-and-forth, how do you get both fans to work with one outlet can you do a video on this just the switching alone is very powerful Thank you.

[@Druze_Tito]

Interesting experiment, thanks for sharing. Subbed

[@darkshadowsx5949]

whats keeps it from sucking bugs into your room? also looks like a nice spot for bees to nest and clog it up. i didnt see an actual air filter despite you saying it has one.

[@pogromcakoparek]

To measure noise, u should put your phone 1 meter from the source. This is the standard distance used to measure noise in a laboratory. Using other distances gives you results that you can't compare to the data presented by fan manufacturers.

[@cmh-re]

as your design is restricting the the airflow, you wont get the 60 m3/h of air displaced, but far less. if you build 2 of your first design, each whit only one fan blowing outside, and change the relay to 2 transistors, you will get the 60m3/h flow you advertised, whit far cheaper material and less time to build. you need to sync them so when one is on the other is off. that way while one is pushing air out, the other is off and will let the air in. also, you need to add a delay timer so that both the fan stop rotating before switching direction, or you doors are gonna open/slam

[@SufyanUmar-w7y]

Please what are the full elemen require to construct this device?

[@frenkprasnikar541]

Hello, Where can I buy this blue round fan. Link please. Thank you and greetings from Slovenia

[@mickwolf1077]

Is the point of this device to reduce temperature difference from inside to outside while a brief ventilation takes place?

[@Lancia444]

Well done on your development - keep it up! Love the video

[@ThomasHeyen]

Your limit is the thermal capacity of your heat exchanger. A 2-way / cross-flow design is more complex but should let you go for a constant low flow rate being quite and economic.

[@jaimes.p.827]

If you sharp the edges of the solid parts of the intake, you'll get a lesser loss of pressure

[@carloslema5400]

What a great idea. Keep up the great work

[@VictorBreazzeal]

this is a neat idea

[@reinux]

How thick is the sheet metal?

[@whateverrandomnumber]

That doesn't make any sense. The air going out the fan is compensated by air entering the ambient from somewhere, unless the room (or whole house) is air-tight, and you're reducing the ambient's air pressure. And that is not how a heat recuperator works. It should have two "air circuits": one with the exhaust air going out, and one with the outside air coming in. They exchange heat on their way (inside air on it's way out, and outside air on it's way in), and then you have a working system.

[@RickLindstrom]

I was thinking the same thing. I just assumed I wasn't paying enough attention and I missed the discussion of the air traveling in the other direction.

[@wjcferguson]

This was also my first thought watching the first attempt, but the second version resolves this with separated input and output paths with a fan blowing inwards on each end. The 3D printed end lets every second segment through, and each end is offset by one. But I expect it'll suffer icing issues for sub-zero temperatures since one end of the device is always the cold end. To resolve that you'd need baffles in ducting so it could be switched to operate in in alternating directions.

[@richardkingadi5511]

I wonder if you could get greater surface area of the recooperator if you were to use something like a bunch of fine aluminium swarf from a lathe?

[@ctrlaltdebug]

Just use copper dish scrubbers?

[@enalaxable]

3D metal printed intertwined heat exchanger opposing flows is the way to go. but too expensive for now. Good try the radial aluminum solution!

[@axel9546]

Whats the difference between this and a real vmc?

[@patrick-zh1lo]

Hi can somebody tell me how he wired the control module and how he programmed it? I cannot see exactly how he did it in the video? If somebody could guide me, I would really appreciate it, thanks! :)

[@titusm9837]

After seeing this video...one thing is clear:))....recuperators are extremely overpriced. This version might have issues with freezing but is a very nice simple solution. Some copper blades would work better - or even copper pipes. Maybe a circular heating resistance from a hairdrier or something similar on the incoming air port - or a wiere like in the other video? I like this version better because it uses less space and it is easyer to integrate in the wall.

[@klausbrinck2137]

One-way-Recuperator-cores aren´t overpriced at all (200$?), since they are made of heat-storing-ceramic, that was invented just recently... A recup-core of aluminium or copper defeats the purpose, since such metals (or any metal for that matter) cannot store heat at all (good heat inductors, the opposite of what a recup-core is). Use 2 ceramic-cores in series, to raise recup-efficiency from 90% to 98%, like the efficiency of big and expensive centralized recup-systems (contain expensive 2-way-recuperators of aluminium, but different working-principle).

[@titusm9837]

@@klausbrinck2137 as far as I understand in this video is a 2 way recuperator. I paid almost 800dolars for prana - 2 way recuperator with almost the same principle but it has copper middle. 2 way recuperators are far superior to single way and ceramic.

[@klausbrinck2137]

@@titusm9837 But it is obviously an 1way, dirty/hot-air-out or cold/fresh-air-in... As said, those are used in pairs, on opposite wals of your house, and when one sucks, the other blows, subsequently the 1st one blows, and the 2nd sucks (recycling). In Germany, they claim 90% efficiency, while the 2-way-cental-ones claim 98% (these are the maximum-performances, for the sweet-spot-air-speed, which might be too low/high for u in several circumstances). But by using 2 ceramic-cores in series, you can greatly raise 1way-efficiency !!! 2-way-ones may have a plastic-recuperator, in Germany, that is as good a heat-inductor, as the expencive aluminium-recuperator would be, but much cheaper... (kunststoff-gegenstrom-wärmetauscher)

[@spacecaptain9188]

Might be fun to try to make this with aluminum cans, and other junk from the recycling bin.

[@tnk657]

Hello it would be very helpful if you posted the wiring. A close up photo is better. Thank you for the video, It's a great idea.

[@mauriceupp9381]

I think if the fans were in a small pipe and the large pipe had your aluminum heat accumulators and then same way coming in that it would exchange heat better because the slow air going through their heating the aluminum up would have more time to eat it as it went through and when the cold air came in it would have more time to suck that heat back off of it does it came back in the house The center of the pipe needs to be large not the end of it

[@jreidel]

Brilliant, thanks for the video. How do you wire the Timer Realy Module? I'm looking for a (slient, non clicking relay), but not sure how to wire two fans like you do in the video.

[@Malainor]

Dame nice, its easy to see that the store version is a "bit" overpriced. As i want 2 for roof, 4 basment, 1 floor level. Store 2-5k🤣, diy 0.6-1k "part dependant". Will check later videos to as alot can happen in a year of testing.

[@GabrieleBonetti]

great! next project a double flow system with continuous countercurrent heat exchange. more complicated but more efficient and don't cause negative pressure that might affect fireplaces or wooden stoves

[@antonmaier2263]

Great work. It may be worthwhile to use a hygroscopic material

[@martas414]

excellent job! I would just use copper sheet - far better thermal conductivity, antibacterial function of copper, does not corrode. Is it possible to update the electronics links? They are already broken. - Or give a name under which they can be searched. Thank you.

[@krzysztofno273]

Well done! You've motivated me so much that I'm trying to make it myself. I just have a question: which program number to set on the relay module?

[@HenningAndersen]

Cool idea, but having a 100 meter diameter hole in the wall seems like a too big drawback for me :/

[@Lazy2cheeks]

Hmm how about making a simular using only one fan? Where you can have a tub inside the same tube. inner tube can push air out. creating a low pressure zone inside which teoreticly would drag fresh air in through the outer layer.

[@oo-yv9cq]

Nice video, could you also make one about the cooler :D

[@pavd8587]

I have an Idea to make similar device but for the heat exchanger I am planning to use a core from car DPF. This will act as 1. heat exchanger, 2. Air filter, 3. sound insulation.

[@SpiraSpiraSpira]

Change the timer circuit to use a mosfet instead of a colicky relay

[@jsjs6751]

The first version was less than 50% efficient. Probably between 30-40. The problem here is that while the air is going out, there will need to be leaking the same amount of cold air in other places in the house. And while the air is going in, you will expel warm air in other places in the house. To get a higher efficiency, you need two units working in opposite phase. Like while one blows out - the other must blow in.

[@NikitaMaree]

Brilliant. Thanks for sharing 👍

[@ekner]

You could make the heat exchanger with the 3d printer too. Less manual work. Use bigger surface area to compensate for plastics lower thermal conductivity, it will work :)

[@nirjharbhatnaagar1982]

@5:17..why there is a 10Rupee Indian currency note there...Did you went to India..! :) ~ñamaste from an Indian~

[@_darkbrian]

Can anybody suggest to me where I can find ready-made units like this, desperately need 2 pcs???

[@GregNewYork1]

I liked the way you build the heat recovery ventilators, can you help me to build a project that I am working on?

[@willyouwright]

I'd imagine the power of the fans supply is more than heat recuperated?.

[@tulipanhr]

HRV system is way more eficient then opening the windows to get fresh air during heating season, also works great when AC is runing in sumer

[@Mack_Dingo]

Coolest thing I learned Hyundai makes TV's

[@joejoejoejoejoejoe4391]

It's possible that glass tubes would be better for the regenerator.

[@brettnevill8237]

Brilliant

[@RixtronixLAB]

Nice video, thanks :)

[@yahmed]

Just Amazing !!!

[@AllanSavolainen]

Don't see this working, the airflows should be separated, not switched. The aluminium has very little heat capacity and cannot store that much heat energy.

[@kreynolds1123]

The concept is good but aluminum tubes is not as good as one might think. I'd like to introduce the concept of volumetric heat capacity. Where as One cm³ of sainless steel has a volumetric heat cacacity of about 3.84 J/cm³°K, aluminum has a lower volumetric heat capacity at 2.43 J/cm³°K. Joules per cm³ per degree rise in kelvin. In other words, a stainless steel straw can hold more energy than an equally sized aluminum straw. But that's not the only problem with aluminum. Aluminum conducts heat too good. One does not want heat traveling down the aluminum pipe from inside the house to outside the house. On thermal conductivity Aluminum: 236 - 431 W/m°K 304 Stainless Steel: 16 - 21 W/m°K If one is ok with aluminum's volumetric heat capacity, plastic straws might be an interesting alternative. Polypropylene: 1.6 - 2.1 J/cm³°K Polyethylene: 1.8 - 2.3 J/cm³°K Polypropylene (PP): 0.20 - 0.35 W/m°K Polyethylene (PE): 0.3 - 0.5 W/m°K Plastic straws might very well be an attractive for their low cost and low thermal conductivity, despit their lower volumetric heat capacity.

[@kreynolds1123]

My initial comment applied to cycling air through straws. If one does counter flow heat exchanger as the later half of the video, the thermal conductivity of aluminum is perfect.

[@seanyushi9096]

Looks heavy. But great work.

[@cutitebucatariebushcraftsu2773]

Hi, how many wires do the fans have and how did you connect them? How did you detect which is the plus to the fan, which is the minus and which are the other wires?

[@ncpanther20]

So that design will not function like a commercial HRV. The design built doesn’t exchange the heat. The heat in a heat exchanger need to move the heat away from the tubes and into the space around the tubes. That generally requires a fan or pump moving air or liquid over the outside of the smaller tubes. The air or fluid on outside of the small tubes needs to be moved away from the tubes and that heat needs to be transferred to a different location then the air moving through the inside of the small tubes. Otherwise it is just a way to bring in unfiltered air slowly.

[@siggyincr7447]

The first design is horribly inefficient with it only working optimally for the short period when it starts drawing in outside air and the aluminum hasn't given up all it's thermal energy. The second design is far better as heat exchange is continuous. As you noted the compact size puts some significant restrictions on how well it will exchange the air in the room. Putting ducts for intake and exhaust that go to the floor and ceiling respectively would already improve the design significantly, giving you room to add sound absorption and air filtration media too.

[@StopaskingformynameYouTube]

How is this supposed to do anything? It's just fans blowing in and out, the thermal density of these pipes aren't going to do much if anything at all..

[@techguy2342]

While I like the idea, you’re losing efficiency doing it this way. Consider this: As air is flowing one direction, the pipes being to change in temperature. As the air/pipe temperature begins to equalize, the heat transfer slows down, to the point very little heat transfer is occurring. When you switch air flow directions, the efficiency momentarily peaks then begins to drop. So overall, the average efficiency is going to be lower than a continuous cross flow system.

[@maartenvd2653]

Nice project but better not use aluminium for the heat exchanger: it conducts heat very efficient, ALSO in the flow direction, thereby reducing the efficiency. Better use a ceramic.

[@ChrisCiber]

A hole 100 meters in diameter would indeed be problematic XD

[@tostane]

the problem is dust and humidity, you would need a much bigger device.

[@horrorhotel46290]

Use copper instead of aluminum

[@spyderguyshishir]

That is 10 inr currency note beside printer 😅

[@jayjenkins6021]

Interesting, but your vid is very confusing. I have no Effing clue what you are trying to accomplish. What is the point????

[@Shinjigitube]

Thanks for sharing your project. Is there a specific reason you chose aluminum instead of copper?

[@hornetIIkite3]

Price probably. Sheet copper is crazy expensive

[@davidcottrell1308]

20 dB of background noise?? Are you kidding??....that is lower than many recording studios......

[@mauriceupp9381]

Mine's English too but my computer doesn't seem to understand me anymore it makes its own words up

[@dhruvgulati1667]

You Indian? Spotted 10rs note

[@devKazuto]

100m in diameter? That's quite a large hole 😂

[@graymouser1]

ai voice or the narrator has the wierdest vocal i flections (or lack thereof) ever. Honestly, it was distracting. Would prefer human voice even if it's accented.

[@aakash8322]

Indian 10 Rupee note in video.... r u Indian

[@wowshorts1566]

5:19 10₹ rupee note

[@michaelseitz8938]

Slava Ukraini comrade 😘

[@barrywilson4480]

$50 to build. First buy $10,000 in printers and tooling

[@oataoc5339]

This is smi truck heater fan not ur project copy cat 😑

[@sanjuansteve]

Laminar flow is great, but not related to heat exchanging.