Residential Standard Gas Water Heater Service Handbook • 11
S
Y
S
TEM CHE
CK
S
SYSTEM CHECKS
Explosion Risk
WARNING!
Before performing any
test, check the area around the water
heater for any source of a flammable
vapor (i.e gasoline, paint thinners,
etc.). If any sources are found, do not
proceed until they are removed.
Dra
Ō
Test
WARNING! Burn Hazard. Do not
touch the vent. Doing so can cause
burns.
After successfully lighting the water
heater, allow the main burner to
operate for
five minutes
. Close all
windows and doors and turn on all
gas appliances and air-moving devices
(range hoods, bathroom exhaust fans,
ceiling fans, etc.) in the home. Also,
close any
fi
replace dampers.
After five minutes, pass a newly
ex
Ɵ
nguished match about one inch (1”)
from the dra
Ō
hood’s relief opening.
Smoke from the match should be steadily
drawn into the opening, indica
Ɵ
ng proper
dra
Ō
and a func
Ɵ
oning vent system.
MATCH
DRAFT HOOD
RELIEF
OPENING
Figure 8.
If the main burner has been opera
Ɵ
ng
for
fi
ve minutes, but the match smoke
dri
Ō
s around or is blown away from
the opening, turn the gas control knob
OFF. Do not operate the water heater
until proper adjustments or repairs are
made to the vent pipe system and/or air
supply (p. 21). Always check the filter
and flame arrestor first and clean them,
if necessary (p. 18).
Connec
Ɵ
ons Check
Some issues can be caused by faulty
connections. Refer to the following list
of connections when troubleshooting
the system:
• Igniter wire (Figure 9). See also
“Testing the Igniter System” on
page 19.
• Thermopile/thermal switch wires
at the gas control valve/thermostat
(Figure 9).
• Wire connections at the thermal
switch (TCO). A disconnected
thermal switch wire can cause the
pilot to become inoperable. See
Figure 4, page 8.
See also “Diagnostic Flash Codes” on
page 10.
Igniter Wire
From Thermopile (White)
From Thermal Switch (Red)
Manifold
Pressure Tap
(1/8” NPT-RH)
Manifold Flex Tube Nut:
ͻWƌŽƉĂŶĞ͗>ĞŌͲŚĂŶĚƚŚƌĞĂĚƐ
ͻEĂƚƵƌĂů͗ZŝŐŚƚͲŚĂŶĚƚŚƌĞĂĚƐ
Figure 9.
Gas Pressure Checks
Gas pressure checks are made with
flowing gas. Use 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.
NOTE:
The dynamic gas pressure
(burner on) should be measured
with all appliances operating that
use the common gas supply.
• Manifold (main burner) gas
pressure is measured at the
pressure tap on the bottom of
the gas control valve/thermostat.
See Figure 9 and Figure 11. Use a
3/16” Allen wrench to remove the
pressure tap plug, then attach the
gas gauge.
NOTE:
Gas outlet pressures will be listed
on the gas control valve/thermostat’s
pressure label. See Figure 10. Also,
gas supply pressure requirements are
shown on the water heater labeling.
VAC
GAS
PRESSURE
GAUGE
CONNECTED AT
PRESSURE TAP
MANIFOLD GAS PRESSURE TEST
GAS PRESSURE LABEL (OUTLET PRESSURE)
Figure 10.
CONNECTED AT PRESSURE TAP
Figure 11.
