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Thread: Pentair Mastertemp 250 Service light on no error code

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    Join Date
    Jun 2016
    Barrie, Ontario Canada

    Pentair Mastertemp 250 Service light on no error code

    Hello all

    First post so here goes

    I have a Pentair Mastertemp 250 heater and it's only a year old. Ran with a loud whine at times last year but worked fine otherwise. This year though it only runs for about 1 minute then the service heater comes on, shuts down for maybe 2 minutes then run again for a minute and the cycle just keeps happening until pool eventually gets to temperature. There is no error code on the display although I see here it says to check the back side of the board and I'm not sure what that means. On the youtube videos showing fault codes they all appear on the display where you normally see the temperature.

    I checked the cartridge filter and cleaned it, pump is working fine, SWG is all good and clean. Water chemistry all good so the issue must reside with the heater itself.

    I understand it's under warranty but I have been on hold for hours over multiple days with Pentair and have yet to speak to a rep and would like to fix it myself if it's a simple issue like a temperature sensor. Any advice appreciated



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    In the Industry

    ps0303's Avatar
    Join Date
    Jul 2011

    Re: Pentair Mastertemp 250 Service light on no error code

    This could be a few things. One that comes to mind is the thermal regulator. Between the inlet and outlet pipes there is a screw off cap and then a spring can be pulled out, hopefully, and attached to is is the regulator. If it is all corroded that could be the issue. If the spring seems stuck, then you also have a broken bypass.

    As for the status LEDs, remove the four screws/bolts on the front and back covers, and then remove the four wing nuts, one in each corer, under the top of the unit. Then you can flip the top over to check the card for the error LEDs.
    Paul A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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