Btw guys, here's a sneak peak of the 2.0 diy hrv unit I'm currently working on.
Featuring two centrifugal EC brushless fans, 650m3/h each, post heating radiator, homemade countercurrent 600mm heat exchanger, freecooling bypass damper and fresh air exclusion damper, all of them driven by 5V step motors. And of course the arduino Mega.
Stay tuned!

Here some new updates from my HRV very close to finish.

cutting the board with hand made tool, very cheap

Attachment 6736 Attachment 6737
Attachment 6738 Attachment 6739

assemble the parts

Attachment 6740 Attachment 6741

testing the dimensions for the parts

Attachment 6742 Attachment 6743

attach the sealings
Attachment 6744 Attachment 6745

Excellent work, congrats!
What kind of glue did you use for the foam?
May I ask how much did you pay for the Recair?

Attachment 6746 Attachment 6747

case for the EC fan 24V 55W each at max. speed, diam 175mm bought from china ~40$

Attachment 6748 Attachment 6749

the box have the bypass channel included on the right side, the dumper is not fitted yet.

Attachment 6750

end the finished product without the controller

Attachment 6751 Attachment 6752

next to do:
- air filters
- controller - speed controll with ballace, flow sensor on exhaust and inlet air, and other feature.
- bypass dumper (maybe with 9g servo or a simple dc motor for on-off shuting


The controller will be one Arduino connected to internet for using Blynk app on my phone, very easy to use.
The sensors will be DS18B20 and for humidity sensing DHT22.

the heat exchanger from Recair cost me ~260 euro / pcs ~ 300 $ with shipping included for 2 pcs.

I don't know the name in english, something calling in romanian "prenadez"
after glueing I leave it for 5-10 minutes end than can be stitch together, like the glue for boots.

@kostas what kind of sensors do you use with arduino and where is placed?

I use the DHT22 for both temperature and RH.
I'll place them like this inside the HRV chassis:

• Income fresh air (in the outside hood)
• Fresh air right after heat exchanger for calculating the COP
• Fresh air after post heater for reading the amount of heated air
• Return stale air
• Bathrooms return stale air (only RH reading) for triggering forced refreshing

Apart these I'll have another DHT22 placed over the oven in the kitchen for the same reason as the bathroom, as well as a relay on the motor of the kitchen hood.
I am currently finishing the dumpers using small Emax servos.
Just got an eye on Blynk, seems cool! Do you have any experience with that?

Thanks for info.

Yes Blynk is very cool, simple and free, if you wand you can do sophisticated apps with the phone. Try it and you will love it!
I have 2 working controllers with blynk and others in progress.

I'm not a coder but is not to hard to stitch together some examples and modify for your needs.
Starting something new you need a lot of time for learning. But now we have on internet a lot of tutorials and examples for learning.

With the hardware part I have good experience.

For the triggering RH sensors what kind of cable you used, how long?

I used a 6 pole cable, the one usually used for home alarm systems, 4X0.22mm+2x0.50mm. It is also shielded so you have no interference problems ;)
I just bought a 7" china android tablet for controlling my HRV at home, I'll install it and give it a try.

Thank you all for the past 49 pages of HRV/ERV info. I can't believe I read every post.

Here is what I'm planning for my office and I have a few questions I would love to get some feedback on.

My office is a 2 story garage that is 60 feet by 24 feet. The second story is unconditioned space and the first floor has 5" of blown cellulose wood cladding on the inside and outside and finally wrapped in galvanized siding inside and out. I don't consider it a tight building but I'm considering this project to vent my bathroom, kitchenette and a small shop and bring in fresh air.

I have plenty of space in the rafters so I leaning to a concentric tube system. The fresh air tube we start at one end of the building travel the 60 feet make a U-turn travel another 60 feet to exhaust. I think I would put the slope towards the exhaust side with and actually drain into the buildings stack.

I'm making it 120 feet believing that more surface area is better. This will also provide the opportunity to collect stale air from both ends of the building while still providing contact to transfer heat.

I would like to deal with humidity using an ERV which I believe is a spinning membrane between the fresh and stale air that exchanges moisture.

Finally I'm aware that I will need to have a negative inside air pressure to prevent moisture from getting into my structure. The question I have is it possible that the negative pressure mechanical produced by ERV/HRV could still be greater then the negative pressure of just a drafty house?

Once again thanks for this site and all it's participants.

Board?
 

Hi,

Whats the name of the foil backed board? I've tried looking for similar, but I've only found foil faced polyisocyanuranate :(

Thanks!