Should we move our air exchange from attic to basement?
threehappypenguins
| Posted in General Questions on
We currently have an old 1980s air exchanger in our attic (split entry home). We will be replacing it with an HRV shortly. But what I’m trying to determine is, should we go out of our way to change all the duct work and install the HRV in our basement? Or can we keep all in the attic. Obviously, it would be way easier just to keep it all in the attic (and save room), but I want to do what is best. I have read that HVAC should always be kept in the envelope of the house. But if it’s only a minor difference, then I don’t want to bother.
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Replies
A heat recovery ventilator stuck in the attic isn't doing too much heat recovery, and the holes in the ceiling are probably increasing the passive air infiltration, increasing heating & cooling loads.
Put it fully inside of conditioned space, both the pressure boundary and insulation boundary of the house. If the basement walls aren't insulated, you'll have some loss of performance, but it won't be as bad as in the attic.
Why wouldn't it be doing too much heat recovery in the attic? If the ducts are insulated, then the warm air going out would still be crossing the cold air coming in, thus warming it up, would it not?
Sarah,
An HRV should be installed inside the conditioned space. You don't want the appliance to be in freezing conditions during the winter, or in a 140 degree room during the summer. You also need good access to regularly clean the filters or change the filers.
-- Martin Holladay
Oh man. I feared that. We bought a foreclosure and installed hardwood floors (there was just bare plywood), and so one of the ducts goes from attic, though a closet, down through the hardwood floor and into the basement. It means we'd have to plug up that great big hole somehow.
If our current air exchange lasted this long, why wouldn't a new one?
Not trying to fight this... just asking questions. We're not starting from scratch, but would have to change the ducting and cover up old holes, etc.
A new HRV should be good for at least a few decades of use. Things tend to last longer and are easier to maintain when they are inside of conditioned space.
Can you share where are you located, and describe your basement insulation situation?
I'm located in Nova Scotia, and my basement is insulated above grade, but most of the bottom concrete portion it (save one room) is uninsulated. The floor is bare concrete.
Sarah,
It's always best for an HRV to be inside the conditioned space of the building, for the reasons cited on this page. But you may be able to get away with an attic installation (in spite of the disadvantages). I would call up the technical help line of the HRV manufacturer to get the company's installation advice.
-- Martin Holladay
That's a great idea. I will do that. We were either going to go with Venmar, or Lifebreath. So I'll call them and ask about attic installation.