Checking The Gas Supply For Pressure; Checking For Sufficient Combustion Air Or Venting Issues; Combustion Air Test - A.O. Smith GCV Series Service Handbook

Checking the Gas Supply Pressure
Gas pressure checks are done with flowing gas using
a gas pressure gauge capable of reading pressure in
inches of water column.
• Supply gas pressure checks are measured before
the gas control valve/thermostat and as close to
the water heater as possible.
• Manifold (main burner) gas pressure is measured
at the pressure tap on the bottom of the gas
control valve/thermostat. Use an Allen wrench to
remove the plug then attach the gas gauge.
NOTE: Desired gas pressures will be noted on the
gas valve label located on the gas control valve/
thermostat.
IF . . .
supply gas pressure is under desired pressure
requirement
supply gas pressure is over desired pressure
manifold gas pressure is more than +/- .3 inch
W.C. from values indicated on gas valve

CHECKING FOR SUFFICIENT COMBUSTION AIR OR VENTING ISSUES

Combustion Air Test

The Installation Instructions and Use & Care Guide
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.
CHECKING THE GAS SUPPLY PRESSURE
WHITE RODGERS GAS CONTROL
VALVE/THERMOSTAT SHOWN
MANIFOLD GAS PRESSURE TEST
. . . THEN
• increase supply gas pressure regulator setting
and,
• increase supply gas piping size.
• add gas pressure regulator.
• reduce setting on existing regulator.
• ensure there is adequate supply gas pressure
• e nsure the main burner orifi ce is the correct size
for the water heater model being tested.
• if the above tests have been performed and the
results were correct replace the gas control valve.
VENT
Figure 17
18
GAS PRESSURE LABEL
GAS
PRESSURE
GAUGE
CONNECTED AT
PRESSURE TAP
Figure 16
EXHAUST FAN
REVERSE FLOW
OF VENT PRODUCTS