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I have this idea, and since it seems logical to me, but I don't see it anywhere I suspect I am missing something.. so here it is:

Why not put a vent that pushes air from the attic into house?

  • At summer, everyone wants to exhaust the hot attic air outside, makes sense.
  • Winter time, the attic still gets hotter, quicker, on cold *sunny day then my house (because I have little direct sun into my house, but also in any well insulated house).
  • why not use the greenhouse "attic" effect, and have a vent sucking the hot air from the attic into the house? you could have that fan linked to a thermostat, only pushing air when attic temp > house temp...

seems easy and cheap, what am I missing?

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7  
My attic is quite frigid in the winter. –  ceejayoz Jul 21 '10 at 22:11
9  
My attic is a quite DUSTY place. Not sure I want a fan kicking on to blow all that insulation debris and dust into the living area. –  JohnFx Jul 21 '10 at 22:18
3  
Your attic shouldn't be more than a few degrees warmer in the winter if it's a properly vented attic. –  DA01 Aug 24 '11 at 15:13
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3 Answers

up vote 17 down vote accepted

Aside from the fact that your attic can be very dirty, you need to be concerned about the following:

  • If you have any gas heating equipment in the attic (central heat, water heater(s)), they may not meet regulations to allow them to be connected to the house's main air supply. You can run a major carbon monoxide (CO) risk from improper ventilation of gas-burning equipment.
  • Pest control companies can use harsher "dusting" pesticides in attic spaces - stuff you really don't want joining you in the house. Insulation is often loose and can irritating. If you have a much older house that might have asbestos insulation, then you have other problems as well.
  • When you pull air out of the attic, it's repopulated by the air from outside. If the air outside is very cold, your attic could reach new low temperatures, freezing pipes or causing other damage. (This may or may not happen, but it's something I would make sure of before attempting this.)
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This is called "positive input ventilation" and is sometimes done in the UK to control condensation. The claim is that the air in the loft is warmer than the outside air and that by pushing it into the top landing you force out the moist air from the house.

Sometimes it works well in older small homes, but there are better systems for new build.

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Depends on your climate I guess, but around here in the winter my roof is covered with snow and the attic is cold even on a sunny day. It seems that if your attic is warmer than your house in the winter, then you either have an insulation or ventilation problem.

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