RESIDENTIAL GAS AND ELECTRIC WATER HEATER
SERVICE HANDBOOK
A.O. Smith Water Products Company
Training Department
©
2002
Ashland City, Tennessee
12
Residential Gas - continued
Sooting causes
:
If …
… then
the burner is clean but the chamber and/or flue
are sooted
check for lack of supply air.
the main burner, chamber and flue are sooted
check the following:
•
incorrect orifice
•
excessive gas pressure
•
loose main burner
•
cross threaded orifice
•
gas control valve gas seepage
•
loose gas connection in burner assembly.
Electrical Testing
This type of water heater has its own electrical
generating system.
When two dissimilar metals are joined together
and this joint is heated, a small, electrical current
will be produced. A thermocouple uses this
science.
Thermocouple output test
Procedures/Conditions:
Meter set for DC millivolt testing
Test from lower ECO (emergency cut off or energy cut off) solder joint to ground.
Note: If pilot will not stay lit, manually hold the top knob down in the pilot position. This allows
gas to flow to the pilot. Light the pilot and continue to hold this knob down while conducting the
test.
If …
… then
reading test of at least 13 MV is not present
•
check that flame contacts end of
thermocouple
•
replace thermocouple.
reading test of at least 13 MV is present
continue to next test.
TO GROUND
