I have a summer fan on my forced air furnace. It can be turned on to
blow fresh air into the house. I am thinking about replacing the fan
wih one that will turn blow in both directions so that at night I can
blow hot air out of the house. My brother has a whole house fan that
cools the house very well. Does anyone have an opinion about whether
reversing the summer fan will have a similar effect?
Well, there may be situations where it may be helpful to blow the air
both directions, but I should point out that you can not just blow air into
or out of your home. For each unit of air that you blow in, the same amount
of air is blown out. Like wise for every unit of air blown out of your home
there is an equal amount of air coming in.
I am not sure what kind of fan you are talking about, but if it is
blowing fresh air into your home, then opening a few windows so the air
there can escape easier, will increase the total amount of air moved.
Where does this summer fan get the air from? If you mean to just run the
blower on the furnace, it will do nothing. If it is ducted to the outside,
it may help a little, but will not do what a whole house fan does. In order
to cool the house, you must vent out the hot air and suck in cooler air. I
don't know what you have now.
The house is supposidly air tight so a duct was installed from the
outside of the house to the interior closet that has the furnace. In
the winter the duct stays shut unless the furnace turns on. However, it
is wired to override the valve that shuts the flap with a toggle switch
so that the duct will remain open all the time, so that in the summer,
the theory goes, I can use the fan on the furnace to pull fresh cooler
air in. It doesn't work that great.
The whole house fan in my brother's place is in the ceiling of his
hallway and pushes household air into the attic space. Cooler night air
is pulled in, I guess, cooling the house very nicely.
I am wondering if putting a fan in the duct to pull air through the
registers out through that duct will work like the whole house fan, or
if somehow this system can be modified to remove warm air from the
house in order to pull cooler air into the house through open windows.
Unless there is a breeze, the cooler outside air doesn't cool the
inside of the house that great and the summer fan doesn't add enough
fresh air to make much of a difference. Will rigging it to work the
other way, pushing warm air out work better?
It seems like box fans and attic fans are wired to pull the hot air out
of spaces and the cooler air is pulled in, passively so to speak.
It's still unclear how this is set up. If the outside air duct just
runs into the furnace closet, it sounds like it is there to supply
combustion air for the furnace. It would have to be connected into
the return air ducts for the blower to draw in air. And if it is
hooked up the latter way, it's a big mistake, as you are drawing cold
air into the house and wasting energy. The correct way of doing this
is to use a heat exchanger, so the outgoing air gives up most of it's
energy to the incoming air. And very few homes have them because most
get sufficient air intake through leaks, doors opening, etc.
Since the house is air tight, where is all this air going???
It sounds like you have a small duct to supply combustion air for the
furnace. The amount of air that might bring in during the summer is so
small at to be immaterial.
If you want to be able to cool you home like your brother, then get what
your brother has, an whole house fan and open the windows to let the air in
and it will be exhausted via the vents in the attic and roof.
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