the Fireplace, Exhaust Fans, the Clothes Dryer and Other Appliances for Air.
National Oilheat Research Alliance 5
showing up. As the technician enters the home,
the outside door is opened, allowing fresh air
to enter. Then as the basement door and boiler
room doors are opened, the pressure equalizes
and the insufficient air problem is “solved” (but
this only lasts until the doors are closed again).
Effects of Insufficient
Combustion Air
For years, it was assumed that a heating ap-pliance
installed in an unconfined space would
have sufficient air for combustion, dilution and
ventilation. However, new building construc-tion
standards reduce a building’s leakage
rate from infiltration, and many of the energy
efficiency improvements that homeowners do
also reduce infiltration. The amount of infiltra-tion
air that enters a home is referred to as air
changes per hour or ACH. The installation of
vapor retardants, more insulation, improved
windows, doors and the use of new construc-tion
techniques all reduce the amount of air
available for combustion, even in unconfined
spaces.
Insufficient air problems are most noticeable
on the coldest days, when the heat loss is the
greatest and the windows or doors are closed
for extended periods of time. These conditions
can lead to incomplete combustion and the
creation of carbon monoxide (CO) inside the
combustion chamber and vent system.