My HRV DIY installation project

creamaster

Last winter after upgrading all the windows,doors, and attic insulation the home became too airtight, blower door test confirmed this, and humidity in the winter became a problem with severe condensation on the windows. Last winter we had to keep a basement window cracked open to alleviate this, but is was freakin cold in the basement and there went alot of the savings in efficiency.

This winter I decided to bite the bullet and install a HRV. I researched them on the web, including alot of useful info from this site. I ended up spending a few extra bucks to get the Venmar unit and so far I am very impressed with it.

Installation took about 4 days. I knew I didnt need alot of registers as just the 1 basement window cracked last year worked well. I also decided to use a dedicated duct system, I did not want to tap into the furnace system and have to run our ineffecient furnace motor all the time. So I decided to put the fresh air supply in the hallway that is adjacent to all 3 bedrooms. For the exhaust air register I wanted to use the wall in the dinnning/kitchen area but due to plumbing,electrical and studs could not. So I tapped into a floor heat register that was installed after the house was built. I closed up this vent from the furnace plenum and tapped into the floor register.

I also wanted to change the basement air so I placed round adjustable registers at the ends of the supply and return lines. I balanced the sytem with a Dwyer magnehelic gauge as per the detailed instructions from Venmar, also they install 4 ports on the front panel to make this a breeze! I simply ran the drain line into the perimeter drain for my basement, this works great as there is not alot of drainage, you could use a bucket if you wanted. I also ran a Venmar humidistat control module into the kitchen/dinning area that has a min/max setting.

So far all winter our humidity has been dead on in the low to mid 30's with 68-70 deg F indoor temps and outdoor temps ranging from 10-32 deg F. We can definitely tell a huge difference with the fresh air in the house. I also dont even need to run the bathroom exhaust fan any longer as the air gets changed out and its not an issue. the HRV runs on the low setting 24/7, and we kick it up to high when we cook soups or have company over. Our energy bill compared to last year is actually better now that we can keep all the windows shut. The HRV on low only uses about 60 watts of power and it has a 75-80% efficiency exchange rating.

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twinAK

Nice looking work. We're going to have one of these installed in our house when we get to that stage, probably another 2 years out. How did you figure out the unit sizing and ducting required? Since the air is not stale anymore, I bet you don't get sick as often. We had too much humidity in our old house and installed a bath fan switch on a programmed timer as a fix since retrofitting an HRV was very expensive. But I'm convinced the HRVs are the way to go from the start, at least in a cold climate.

Tim

creamaster

Thanks.

As for the unit sizing there were different methods posted on the web, but the easiest was figuring for the number of occupants and then so much per room/kitchen/bathroom. The smaller unit wasnt that much less in price, the 1.0 model, and the 2.0 was too much air, so the 1.5 seemed to be just right for this setup.

As for duct sizing, the unit has 6" ports so your main trunks would be 6" for this unit, if you had multiple branches for your all your rooms, then you could likely use 5" for these. The instructions gave good information about selecting the proper duct size for the minimum CFM air movement.

As for being sick, we were doing very well all winter until last week our son got sick and we all got it, but I would have to say the fresh air really helps with indoor air quality, like when cooking the odor clears out of the house much faster. I have decided to not go ahead with a kitchen exhaust fan to the outdoors now because the HRV does so well. When you put your face near the fresh air register you can smell the freshness, its like being outside yet without the really cold part

This unit can be retrofitted with an ERV core, I am thinking of doing this for the summer just for the basement so I can refresh the basement air yet not bring in the outdoor humidity. I will have to see how much the ERV core will cost.

twinAK

Thanks for the follow up. I'll have to do some research and consider doing it myself. If it's not too complicated I might take on this part of my build too. But if the cost savings aren't considerable enough to offset the learning curve I may just hire this one out. Thanks again

Tim