RESIDENTIAL GAS, NON POWER VENTED, WATER HEATER
SERVICE HANDBOOK
State Water Heater
Technical Training Department
© 2004
Ashland city, TN
10
Residential Gas - continued
Service:
Air:
A gas burning appliance requires the oxygen contained in 12.5 cubic feet of air (at sea
level) for every 1000 BTU of heat that is generated. If your water heater has a BTU per hour
input of 40,000 BTU then a minimum of 500 (40 times 12.5) cubic feet of clean air must be
available. This oxygen will mix with the gas for a clean, blue flame in the burner chamber and
provide dilution air for flue products.
Do not forget that your gas (or oil) furnace and gas clothes dryer also require a like amount of
air.
When calculating air supply provisions, also consider the presence of whole house exhaust fans
or other exhaust fans competing for the same air supply.
Air must be allowed to enter the heater chamber from the base of the heater and also enter the
flue vent from below the draft hood. Do not block these areas with insulation blankets or
obstructions lying around the base of the heater.
Lack of Oxygen:
If a sufficient supply of oxygen (air) is not available for combustion and
dilution, the result will be:
•
Pilot
outage
•
Yellow burner flame
•
Sooting water heater
12.5
Cubic
Feet of
Air
+
=
1,000
BTU
Fuel
(Enters
Here)
(Enters Here)
