Pentair Mastertemp 250 Service light on no codes given

coachsully

New member
Feb 1, 2021
1
New Orleans, LA
I have a Pentair Mastertemp 250. I get the service light on after about 15-20 mins. I do not get any error codes and none of the codes on the back of the mother board light up. I have replace the thermo regulator and the manifold bypass valve. The temperature inside the coil chambers in getting to hot and shutting down the heater. It get to about 425 and then shuts down. I know the temperature inside the chamber so be between 210-350. I am not sure what to check next and I am pretty sure it is not a water flow issue or and air flow issue. Any suggestions would be greatly appreciated.
 
Are you sure that the SFS LED is not coming on?

The following are the LEDs:

1.....PS (Pressure Switch)
2.....HLS (High Limit Switch)
3.....SFS (Stack Flue Sensor)
4.....AFS (Air Flow Switch)
5.....AGS (Automatic Gas Shutoff).
6.....Service System
7.....Thermistor
8.....Heating
9.....Pool On
10...Spa On
11...Service Heater.

Check out this reference.

 
SFS LED does not latch on and will reset and go off once the heater cools down. You have to catch the LEDs right after shutdown to determine what is happening. Otherwise the heater will cool down, reset itself, and recycle.
 
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