MASCOT MSTWW, Installation And Operation Instructions Manual

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LAARS Heating Systems
Page 48
Error
Code
Error Code Description Possible Remedies
Recover
methods
33
Operating
Temperature Sensor
Open or Short
This Error Code will go away when outlet water temperature decreases.
If Error happens again:
1. Check operating temperature sensor. Ensure connections are secure.
2. Check sensor resistance. If resistance is zero, replace the sensor.
3. If the problem persists, replace the main control.
Soft Lock
35
Exhaust Sensor Open
or Short
This Error Code will go away when exhaust temperature decreases.
If Error happens again:
1. Check exhaust temperature sensor. Ensure connections are secure.
2. Check sensor resistance. If resistance is zero, replace the sensor.
3. Check exhaust vent for blockage.
4. If the problem persists, replace the main control.
Soft Lock
39
Flame Detected after
Exiting a Flame On
Condition
This Error Code will go away when the false flame condition is remedied.
If Error happens again:
1. Check the water heater cover. Ensure it is secure. Flame detection sensor can detect an external
light source.
2. Check flame detection sensor. Ensure connections are secure. Normal operating settings are more
than 2.5DC before ignition, less than 2.5DC after ignition.
3. If the problem persists, replace the main control.
Soft Lock
40
Gas Leakage is
Detected in 10
Minutes, or three times
within One Hour
(Greater than 5
Seconds Each Time)
IMPORTANT: If you smell gas, STOP! Follow the instructions on page 2, this manual, and call a
qualified service technician or the fuel gas utility.
Press the Power button to clear the Error Code.
If Error happens again:
1. Check the water heater cover. Ensure it is secure.
2. Check gas connections for leakage with a soapy solution. Fix any leaks.
3. Check condition of the burner assembly.
4. If the problem persists, replace the main control.
Hard Lock
41
Fan Speed too High
with Flame On
Press the Power button to clear the Error Code.
If Error happens again:
1. Check the vent connections for blockages.
2. Check the burner assembly.
3. Check fan operation. If fan appears to be operating normally but RPMs are too low or too high,
replace the fan.
4. If the problem persists, replace the main control.
Hard Lock
43
Burner Overheat
Switch Open
Press the Power button to clear the Error Code.
If Error happens again:
1. Check burner overheat switch connections. Ensure connections are secure.
2. Check switch resistance. If resistance is zero, replace the switch.
3. If the problem persists, replace the main control.
Hard Lock
61
Fan Speed Feedback
Signal Abnormal
This Error Code will go away when the condition is remedied.
If Error happens again:
1. Check the connections to the fan. Ensure all are secure.
2. If the fan does not rotate during the ignition sequence, check for 120V power at the fan connection.
If 120V power is present at the control, replace the fan. If the blower does not have 120V power, check
power at the control. If 120V power is not present at the control, replace the control.
3. If the problem persists, replace the main control.
Soft Lock