You have to figure that anytime you are pumping air out of the house - as
with dryer, furnace, regular fireplace, a pellet stove , or just a bathroom
or kitchen exhaust fan- air has to come back in to replace it. Unless you
live in a super-insulated house, air will find somewhere to enter, or the
device try to exhaust will fail to function properly. So by bringing
outside air in for the combustion process in a controlled fashion as the
appliance manufacture suggests, you save having that same air drawn in thu
windows, doors, or what ever other opening it can find.
Since this is for the combustion, it ends up being blown out of the house
via the chimney or whatever other exit point might be used by the appliance
to vent combustion gas. (i.e. a high-efficiency furnace might use regular
This isn't the air that is being heated by the appliance - that is the room
air around the stove, which may be drawn in by a fan and circulated around
the outside of the combustion chamber and heated before being blown out as
hot air to heat your room.
I don't believe my house is air tight, especially with a cellar drain.
There is no trap on the cellar drain because it don't go into a sewer.
I'm sure air comes up that pipe just fine. There is a screen on the
outside end to keep the little animals out. I guess it's too long a
tunnel for the bugs.
The dryer is certainly making a slight vacuum. If you are blowing air out,
it has to be replaced somehow, usually through all the tiny leaks you have.
The pellet stove (or woodstove, oil burner, gas furnace) will be venting the
exhaust to the outside. As long as air is going out, more cold air is
coming in. By moving the combustion air inlet to draw directly from
outside, you don't take the already heated air and exhaust it to bring in
As for the energy, yes and no. You need a certain amount of Btu to get the
air to the point it can be used for combustion. However, you are also going
to take air that you paid to heat already inside the house and heat it up to
burn and, as I sated, it will be replaced by cold outside air. It can even
create serious drafts in some homes, depending on construction.
No house is air tight. Do some searching and you'll find information on
testing that is done and how they house can be pressurized to find the
leaks. Start here
My point was that, if the outlet is in the middle of the house, like our
center chimney, there's no way to direct outside air to the comubstion
chamber without being ridiculous. Pellet stoves draw combustion air from
the bottom anyhow, where it is coolest in the house, and just that draw
tends to pull warmth down from the ceiling to the living zone. A pellet
stove is very different in dynamic from a wood stove; more like your oil or
gas burner, which don't recommend outside air.You can hold your hand on the
top of a pellet stove all day without any more harm than feeling ridiculous.
Want me to send you a photo of the outside air intake on my oil burner? Or
from the gas burners at work? All installed at the manufacturer's
It may not be easy to install in your case, but the reason it is recommended
does not go away. Every cubic foot of air that goes up your chimney is
replace by an equal amount of air from outside. Just one of those laws of
physics that we cannot get around.
Oh, and my oil burner is in the center of the house and yes, the fresh air
inlet is ducted to it via 2" PVC.
Outside air ducting has another benefit in that when the stove or burner is
not in operation, there is no heat loss up the chimney from air just being
drawn up through it and wasted. This saves heat and the associated costs.
Personally, I don't care what you do in your house but now you know the
reason for it
I was thinking of putting the air intake up through the ceiling into the
attic. There outside air can be drawn in from the roof vents and any
heat leaking up through the floor can be sucked back down. Since the
ceiling is right above the stove it's a short run.
Say what you will, but pellet inserts don't have intakes for outside air.
Why would they, anyhow? They put the heat directly back into the home ... I
can put my hand on the exhaust and keep it there when the stove is at its
hottest. If your oil burner is in your kitchen or living room, where our
stoves are, your intakes must be a pretty sight, and somewhat of a threat
when you walk if the the air is drawn in at the bottom like it is on a
Say what you will, but if the is an outside exhaust, efficiency can be
improved with an outside air intake. Laws of physics, not my opinion or
your. Educate yourself and you will agree. My oil burner is in the
basement, not the kitchen.
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