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COMMERCIAL GAS DAMPERED WATER HEATERS
No Hot Water
NO
Repair
power
problem
Check for 24V
YES
between PV &
PV/MV terminals
on gas valve
NO
Replace
gas
valve
Check for 24V
between PV &
PV/MV terminals
ignition control
module (ICM)
NO
YES
Replace
ICM
OK
Check gas supply
Repair
gas
supply
Go to
thermostat
troubleshooting
flow chart
FCG3-0805
DCG3 SERIES
High water temp.
YES
Will ECO light
reset once temp.
in tank cools?
Power to
heater?
YES
YES
When thermostat
is turned up
does pilot spark?
YES
NO
Does pilot light?
YES
Does sparking
stop?
NO
Clean flame
sensor - check
ground. If still
problem,
see below
Bad spark
assembly or
wiring between
spark assembly
& ICM
Does main
burner fire?
YES
Does
ALL
main burner
YES
SHOULD
stay lit until
BE OK
thermostat
satisfies?
NO
Does pilot light
shrink or go out
NO
when main
burner fires?
Copyright© by American Water Heater Company 2005. All rights reserved.
Check continuity
across ECO
NO
CLOSED
Is ECO light on?
NO
Check for 24V
between purple
NO
and white wires
on the ignition
control module
Check for 24V
NO
between PV &
YES
MV/PV terminals
ignition control
module (ICM)
Replace
ICM
Check spark wire
for damage &
FOUND
continuity. Also
DAMAGE
check spark
assembly for
cracks in ceramic
or wrong spark
Replace
faulty
component
Is there 24V
NO
between MV &
PV/MV terminals
at gas valve?
YES
Check for
blockage in
burner or orifice,
also check
incoming gas
Is gas flex being
YES
used, or other
small pipe?
Replace
ECO
OPEN
thermostat
troubleshooting
flow chart
Is ground good
NO
from control
module to
incoming ground?
(ICM)
YES
YES
Check for 24V
between orange
& white wires on
damper harness
YES
NO
ALL
OK
gap
Replace
ICM
Is there 24V
NO
between MV &
PV/MV terminals
at the ICM?
NO
supply
Check &
NO
adjust gas
pressure
Replace
gas
valve
Go to
NO
Repair
Ground
YES
Bypass
damper,
orange & purple
wires, if heater
fires then
replace
damper
Go to
thermostat
troubleshooting
flow chart
NO
Replace
ICM
OK
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