Just joined the forum hoping someone could help me solve my head scratcher. I have a 5 year old Pentair Mastertemp 125 natural gas heater. I have had very few issues with it apart from replacing the AFS last year. I went to start it up this year and no ignition. Bower starts, gas valve opens and then immediately it gives me the AFS led and cycles. This will happen 4-5 times and it will go into lockout until i reset it. I have checked the AFS and it is operating normally. I have even jumped the sensor during startup with the same effect. Flow switch, ignitor, and thermistor all test fine. I'm leaning towards the control board or the ignition module but don't want to just throw money at it. Any suggestions would be great, thanks
mastertemp 125 issue
- Thread starter cbyard
- Start date
- Jul 21, 2013
- 53,077
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
You can't simply jump the Air Flow Switch during startup. At startup it first checks for the AFS to be OPEN. If the AFS is closed then it will immediately throw the AFS code.
Right, that's why I said during startup. Have done this before to troubleshoot this unit as well as furnaces.
System is wired to 120v . If you mean the transformer I haven't tested but will do so. Not any obvious signs of mice. Thanks
Is the correct voltage selector plug installed?
If you have the 230 plug installed and 115 volts as the power, the fan will run too slow and cause an airflow problem.
Note: Do not change the plug unless you are 100% sure that you know what you are doing.
If you install the 115 volt plug with 230 volts input you will seriously damage the heater.
Last edited:
yeah. the correct plug is installed. the unit has been working for past 5 years. I did replace the AFS sensor last year and it worked until winterized. Thanks