I want to insulate my garage door better because cold air is coming in from
the bottom and side.
However, there are a gas furnace and gas water heater in the garage that use
the ambient air. So if I seal up the garage these two applicances would run
out of oxygen.
Is there a way to retrofit the two appliances so they draw air from outside
My HVAC guy put a vent near the water heater. As far as the furnace,
depends on the furnace. Our local Habitat for Humanity Restore had a 90%
furnace for $125 in nice condition. They use outside air and it never mixes
with the inside air.
Some of the newer furnace do have a hook up for supply air as well as
exhaust air. Have not seen that on a hw heater yet though. Just run
a 4" pvc pipe from outside to the proximity of them. Put a screen on
Here is what I thought was an interesting article on the "myth" of
using outside combustion air for wood burning appliances.
While I certainly don't claim to be a "combustion scientist", it seems
to me that the same principals would apply to gas appliances.
Key question: Do you really think you can seal up your garage door to
the extent that it will be air tight?
On Wed, 9 Dec 2009 13:26:00 -0800 (PST), DerbyDad03
This part, near the end, seems suspect to me "Building scientists say
that the air in a house must be exchanged at least every three hours,
or one-third of an airchange per hour, to control moisture from
cooking and washing and to manage odors. One third of an air change in
a 1500 square foot house is 4000 cubic feet, or 66 cfm. Note that this
is the absolute minimum air change for healthy living and that most
houses older than 20 years have natural leakage rates far higher than
this in winter. So the air consumption of a wood stove is a tiny part
of a much larger exchange of air between the house and outdoors."
My house is pretty darn leaky, but i don't believe the air is changed
every 3 hours. I doubt that is true even in the summer when some of
the windows are open, but I really can't imagine it's true in the
winter when they're not.
The code here is that a gas furnace in a garage must be enclosed in a
"closet" type of enclosure-- presumably so that if the car leaks
gasoline fumes, the furnace will not ignite them. You can get combustion
air through the ceiling in the closet, since most furnaces in that type
of installation are not on an outside wall. It also requires 1 square
inch of opening for every 1000 btu of input. The 90+% efficiency
furnaces that vent with PVC are all but non-existant here- S Tx. Larry
Their are code in most area for that, and don't play games with ventilation
air make up is require for furnace or hot water heater, specially where
garage is attached to the house.
saving little in heat could cost you life???
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