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Thread: Pentair Minimax Pool Heater

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    Pentair Minimax Pool Heater

    ***Please Help*** I have a Pentair Minimax 400 inground pool heater that is 9 yrs old. When I turn it on, after @30sec it begins making a popping sound. At first I thought a rat or squirrel was in the heater and was jumping around. Took top off and did not find anything but isolated the sound to the flow valve assembly. Took this out and copper tip noted to be broken off. Just replaced with brand new one but still making popping noise in this area. Heater will only stay on for few seconds then shuts off. Technician at Pentair says pipes may be clogged but this is not the case. Any help would be greatly appreciated!

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    Join Date
    May 2007
    South Central NJ

    Re: Pentair Minimax Pool Heater

    Bet it is. Did you take the header off to see? The popping is likely boiling water in the heat exchanger and the high limit kicking in to shut it down.

    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

  3. Back To Top    #3

    Re: Pentair Minimax Pool Heater

    Yes, took the header off but could only see the entrance to the pipes. No build up seen. Will be using a fiberoptic scope next to see if there is a clogged pipe. Will follow up. Thanks for your response!

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    Re: Pentair Minimax Pool Heater

    Is it condensate dripping down inside the cabinet? Inside or outside application?

  5. Back To Top    #5

    Re: Pentair Minimax Pool Heater

    Fiberoptic viewing of the pipes shows no blockage. There is no condensation either, Bruce. However, I may have found the problem today. I just noticed another valve was open which is diverting at least half the water input. With less water, the boiling point is reached, thus the knocking sound at the flow valve assembly. Just put it back together so will test in the morning. I am hopeful that this will solve the problem.
    Thanks Bruce and Scott for your input!

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    Re: Pentair Minimax Pool Heater

    I think you found your culprit! Good job Please post up the good news when you are sure that is it!

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    Re: Pentair Minimax Pool Heater

    Fired it up this morning and no more knocking! Now have a new problem. The heater stays on 1 min 15 sec then cuts off for 15 sec and then relights and does same thing over and over. I thinks this could have something to do with the high-low limit. Any comments on how to verify?

  8. Back To Top    #8

    Re: Pentair Minimax Pool Heater

    Check your temp between the "in" port and the "out" port. Normal temp (IIRC) is around 4 degrees difference. There should be an adjustment screw that you can turn to make the temp fall into place.

    You should be bypassing some water to blend the water, so that you do not send scalding water back to the pool. This is controlled here and is why the temp difference is so small. There is a gauge called "Pete's Plug" that you can get to check both sides that threads in to the headers.

  9. Back To Top    #9

    Re: Pentair Minimax Pool Heater

    Ok, will check tomorrow and follow-up. Right now, pool is heating but heater works for 1 1/4 min then cuts off for 1/4 min. Hope that is not hurting anything. Thanks Bruce for your response!

  10. Back To Top    #10

    Re: Pentair Minimax Pool Heater

    Keep us posted; we'll get you up and running again

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