Pentair Mastertemp 125 Troubleshooting

If you are having problems with your Pentair Mastertemp 125 Pool Heater, you are not alone. Many Pentair Mastertemp 125 owners experience issues with their pool heater from time to time, and it can be frustrating to deal with these problems.

I have problems with my Pentair Mastertemp 125

Pentair Mastertemp 125 Pool Heater Problems

Pentair Mastertemp 125 Replacement Parts

Troubleshooting a Pentair Mastertemp 125 Pool Heater

Share your Pentair Mastertemp 125 Pool Heater Problems, issues , tips, ideas, and frustrations with other owners.

  1. Loud popping sound when heating.
    High pitched whistle that stops when you take a side panel off, when hehating.

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  2. I can’t find a water drain plug for winterizing my heater.

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  3. I have had error codes and had parts replaced. After turning on the heater, in the first 5 minutes or less it shuts off and says service heater. I have noticed since it was installed 2 years ago, it doesnt seem to have as much exhaust pressure coming out. There don’t seem to be anything blocking the exhaust either. Help anyone?

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  4. Pentair Mastertemp 400HD: connected to a pool only, starts up just fine, runs for a few minutes sometimes to about 10 minutes to even 25 minutes then Heater shuts off, goes into spa on (No spa connected) and the control panel displays a temperature reading of 215 F then starts to decline. I have no error codes, or lights on the back of the control panel. If I turn the pool on again, same thing, it will run then shut off minutes later. I have replaced the Stack flue sensor, the Thermistor, Thermal regulator, High Limit Switch and the Automatic Gas Shut off. I used a meter to check the conductivity of all electrical connections, all good. Since it fires up, the control panel is working, heat is set to 84 and displays water temperature heating from 76-80, it runs for a few cycles so I am steering away from ignition issues and thinking Gas Valve. Any thoughts??

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  5. I can’t raise the temperature. It shows pool and spa temp. but when I push the up button nothing happens.

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  6. I have my boiler set @ 83 degrees and it shuts down at 77in service mode

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Pentair Mastertemp 125 Issues? Need Help?

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