Air for Combustion

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MarkF48

Feeling the Heat
Nov 14, 2011
270
Central MA
I was looking through the instruction pamphlet for my coal stove/heater the other day and noticed a safety precaution that I'm not sure would be applicable to other stoves as well including pellet.

"Provide Air for Combustion
Combustion of any type fuel requires oxygen. Be sure adequate makeup air is provided to the room where the heater is located. If necessary, a window should be opened an inch or two slightly to insure proper outside air supply and to prevent oxygen exhaustion below a safe level to support life."

I understand an OAK on a pellet stove would negate an issue like this, however a stove that has no OAK should draw all air from a room and not just selectively the oxygen. If were to draw all air without replenishment, wouldn't this just create a negative pressure in the house, which in all likely hood wouldn't occur due to normal house leakage that exists? A stove exhaust is vented to the outside, so the byproducts of burning such as smoke and other gasses don't displace what is taken in from the room.
If a condition like this is possible, is there a way to check for it? I'm not particularly worried myself as my house was built in the late 1800's and leaky as hell and the mice seem to know the outside "venting" holes to enter through, but just rather curious as to the precaution.
 
It should not be an issue. You are correct it will create a negative pressure in the house and make up air will come from the outdoors.
 
They might concerned that if the house were pretty air tight, the stove would starve for oxygen and airflow, and might back up into the living space. If exhausting appliances are used, they could even draw the air back down the vent, through the stove, and into the house; a dryer, kitchen vent, oil fired furnace, etc.
 
IMHO you need to consider all the appliances AND the occupants of a home when you consider whether you need make-up air for your appliances.

It's not far fetched to say that under certain conditions you could run out of oxygen... think about an well sealed home, family get together with a big family, gas stove and range cooking the meal, a gas water heater on the main floor, maybe a gas clothes dryer in operation and a pellet stove or fireplace keeping everyone warm. You could run out of oxygen...

This is why I have always been a promoter of an OAK... I guess it goes back to my Dad who used to be very careful about stuff like this back when we heated our homw with a coal furnace and a small gas space heater... he always had a window cracked open for safety's sake.
 
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