Service Manual

Steady State Operation.
During Steady State Operation the Control Monitors:
Thermostat temperature sensor- When set point temperature issatisfied,gasvalveis shutdown and
blower will postpurge for 15 seconds. Control LED flashes a short flash onceevery 4 seconds (idle) status
code.
Pressure switch /Blower temperature switch- If either switch opens, pilot valve and main valveis shut
down. The blower continues to runsfor 30 seconds attempting to closethe circuit. The control LED Flashes
3 times with 3 second pause.
Flame Sensor- Ifflameis lost, pilot & main valve are shutdown,blower runsfor 15 seconds.
Control attempts
to re-light pilot 4 times.Ifunsuccessful,Blower is shutdown and control proceeds to 5 minute lockout. Control
re-attempts to light pilot starting at normal heatingsequence#2.
Thermostat Satisfies.
Burner Off.
Blower Post Purge (15 seconds).
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Sequence ofOperation
Abnormal Operation
1.Simulated ResistiveDeviceFault:
a)Ifthe resistance is greater than 70,000 Ohms - the gascontrol immediately turns off all outputs. Control waits
and monitors resistance for 30 seconds.If theresistanceisgreater than 70,000 ohms after 30 seconds, the
gascontrol proceeds to verifyresistive delay
for 2minutes and flashes 8 times then once with athree second
pause. This process is repeated 5 timesuntil the control either returns to normal operation or proceeds to flashing
7 times with a3second pause.
b) If the resistance is below 3000 ohms - The gascontrol immediately turns off all outp
uts and proceeds to flash
8 times then once with three second pause. The error selfclears if theresistance returns to normal range for at
least 15 seconds.
Normal Heating Sequence (cont.)
2. Temperature Sensor Fault:
a) Temperature sensor detected open circuit - The gascontrol Immediately turns off all outputs and proceeds to
flash 8 times then twice with three second pause. The error selfclears if the fault clearsfor at least 15 seconds.
b) Temperature sensors not reading the sametemperature within ±5.5 °F - The gascontrol Immediately t
urns off
all outputs and proceeds to flash 8 times then three times with three second pause. The error selfclears if the fault
clearsfor at least 15 seconds.
c) Water temperature in excess of ECO (Energy Cut Out)limit - The gascontrol immediately turns off pilot &
main valve and proc
eeds to flash 4 times with 3 second pause. Blower continues to run until gascontrol is reset.
The set point knobshould beturned to the minimum temperature settingfor at least 6seconds and then turned
clockwise by at least45
o
.
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