Service - A.O. Smith TC-049R3 Service Handbook

RESIDENTIAL GAS AND ELECTRIC WATER HEATER
Residential Gas - continued

Service:

A gas burning appliance requires the oxygen contained in 12.5 cubic feet of air (at sea level)
Air:
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.
If a sufficient supply of oxygen (air) is not available for combustion and
Lack of Oxygen:
dilution, the result will be:
•
Pilot outage
•
Yellow burner flame
•
Sooting water heater
•
Possible carbon monoxide
•
Smell of burnt gas in the room
A.O. Smith Water Products Company
©2005
SERVICE HANDBOOK
(Enters
Here)
1,000
BTU
Fuel
(Enters Here)
12.5
+
Cubic
Feet of
Air
Technical Training Department
10
=
Ashland City, TN