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