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

Page: 12 / 69

RESIDENTIAL GAS AND ELECTRIC WATER HEATER
SERVICE HANDBOOK
Residential Gas – continued
The instruction manual gives guidelines under “Air Requirements” and “Unconfined “ or “Confined
Space” sections. If you want to test for a lack of air:
1. Turn on every appliance and fan that exhausts air from the utility room and/or house.
Make sure all windows and doors are closed, as well as chimney dampers.
2. Open a hot water faucet so that the main burner will ignite
3. Remove the outer door of the water heater – not the inner door
4. Monitor the flame characteristics for several minutes
If the flame begins to “yellow” open a door or window, to the outdoors, to see if additional air
corrects this back to blue. If it does, the room needs more air supply. Perform draft test at draft
hood of water heater with match or smoke source to verify.
A.O. Smith Water Products Company Technical Training Department
©
2005 Ashland City, TN
11
Manifold
Gas Pressure
Test
Testing with
Gas
Pressure
Gauge
Pilot Gas
Pressure
Test
Gas pressure checks are done with flowing gas.
Supply gas pressure
checks are taken ahead of the gas control and as close to the heater as
possible.
Pilot gas pressure
checks are taken by using fitting adapters to tap into the pilot gas tubing.
Manifold (main burner) gas pressure
is measured using the Allen wrench tap on the bottom
of the control valve.
Desired gas pressures will be noted on the gas valve label.
If … … then
supply gas pressure is under desired pressure
setting
•
increase supply gas pressure regulator
setting and,
•
increase supply gas piping size.
supply gas pressure is over desired pressure
•
add gas pressure regulator.
•
reduce setting on existing regulator.
pilot gas pressure is more than +/- .3 inch
W.C. from desired replace the control valve.
manifold gas pressure is more than +/- .3 inch
W.C. from desired replace the control valve.
Additional considerations when pilot or main burner flames are too large or too small:
•
Incorrect orifice
•
Dirt in orifice or gas supply tubing