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Service Procedure II:
Combustion System Testing and Replacement
Observe burner operation through the sight glass located on the combustion insert mounting flange. Normal burner
operation should ignite smoothly, without evidence of coughing or huffing upon ignition. The burner flame should be a blue
flame near the burner surface in a uniform flame pattern. Occasional yellow or white streaks are normal.
Note: On this high input model that uses metal fiber mesh burner a red glow from the burner surface is normal.
120 volt potential exposure. Isolate the
appliance and reconfirm power is disconnected
using a multi-meter.
WARNING
Continued from previous page
N
Refer to control board illustration, is
there 24VAC between brown and
blue wires coming out of the control
harness during the flame establishing
period? (Note: Control display must
show “Heating” for operating status).
Check to see
brown and blue
wires are
properly
connected to
molex
connectors on
control harness.
Can you hear or feel gas valve
energize?
Replace gas valve harness
and/or gas valve. (See “Gas
Valve Replacement
Procedure”.)
Does burner light smoothly,
without evidence of coughing
or huffing?
Check for obstruction at inlet
of gas valve. Is inlet free of
obstruction?
Clear
obstruction
Inspect burner
tube, (see “Burner
Tube Inspection”).
Does burner stay lit?
Does burner operate
normally until
thermostat is satisfied?
Call for
technical
support
Check flame sensor. Are
there at least 1 to 5 micro
amps (min.) during 1.5
second flame proving
period? (Value may be
displayed on the control
display by accessing
“Service Mode”.)
System O.K.
Replace flame sensor (see “Flame
Sensor Replacement Procedure”).
gas valve/venturi
Y
Y
N
Y
Y
Y
N
N
N
N
Y
Y
N
N
Replace control
Make connections
N
Y
Inlet
Pressure
Tap
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