Hi,
I always thought air exchangers were a pretty cool idea but I never needed to install one. Now I live in a house that is pretty tight and there are 4 or 5 of us living here. The problem is that the one bath vent hose drips water back to the ceiling and the heat ducts in the attic are filling up! I checked the humidity-its 53% at 32F outside. It’s supposed to be about 40% from what I’m reading. Both baths have vents but the kitchen doesn’t. Guess that’s the first thing I should do.
I know the theory behind air exchangers but in reality, how is an air exchanger any better from an energy standpoint then cracking a window? Cold air is still allowed in-so what if you’re heating it with inside air first? Am I missing something?
Thanks, Jon
Replies
I got one. It works fine.
You need it if you have a tight house, and especially if you have a tight house and your furnace uses outside combustion air.
What it does is two things: First, it does the obvious--it exhausts inside air and replaces it with outside air. But more importantly, it warms the incoming air by exchanging the heat with the outgoing air. So, you vent the house and save energy.
I know the theory behind air exchangers but in reality, how is an air exchanger any better from an energy standpoint then cracking a window? Cold air is still allowed in-so what if you're heating it with inside air first? Am I missing something?
Yeah, you're missing something.
You need 0.35 complete air changes per hour to maintain a healthy indoor environment and control humidity in a tight house. Opening a window, first of all, doesn't guarantee any specific exchange rate, and secondly you're just heating the outdoors.
In a 2000 sf house here in VT, you would be tossing 70 gallons of fuel oil or 9,160 cf of natural gas or a half a cord of firewood out the window each year. With a 70% efficient HRV, you can save nearly 3/4 of that - and guarantee the minimum air exchange for a healthy home.
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