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Thread: Pentair Minimax NT Heater

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    Pentair Minimax NT Heater

    Hi guys,

    I have a spillover spa that is heated with a minimax heater. When I set the temp the heater kicks on and heats the water up about 5 degrees...and thats it. It will then continue in the heat mode but the water will not get any warmer. Any ideas?

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    Join Date
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    Re: Pentair Minimax NT Heater

    Welcome to TFP!!

    Sounds like the heater thinks it has achieved the desired temp and stops heating. What temp are you looking for and what temp does the heater say the water is?
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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    Re: Pentair Minimax NT Heater

    I set it at 100 and it may get to 88 or so...actually heats less then 5 degrees. It also stops then starts again, when it starts there is cool water coming in.

    But even when the heat runs when it reaches a certain point it just stops heating.

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    Re: Pentair Minimax NT Heater

    Someone suggested I clean the burners? Could dirty burners be causing this?

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    JasonLion's Avatar
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    Re: Pentair Minimax NT Heater

    What happens when you set it to 105? Do you see any error indications?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Pentair Minimax NT Heater

    Nope. It just runs for a bit (heating), then stops, recycles itself, then starts heating again. But it never warms the water past 4 or 5 degrees. I let it run for like 2 hours, it ran the whole time (stopping and starting), putting warm water in the spa but it "levels off" after a while, then it doesnt get any warmer.

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    Re: Pentair Minimax NT Heater

    The overspill is running the whole time to....I suppose it could be dumping whatever hot water comes in back into the pool?

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    JasonLion's Avatar
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    Re: Pentair Minimax NT Heater

    If the spillover is running, it won't be able to warm the spa up any further until it heats the entire pool up, which will take a very long time.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Pentair Minimax NT Heater

    Then I need to turn the overspill off? I dont think my pool guy plumbed my pool right....If I turn the overspill off then the spa fills up with water...

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    JasonLion's Avatar
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    Re: Pentair Minimax NT Heater

    There should be two valves, one selecting where the pump gets water (pool or spa) and the other selecting where the water from the pump goes (pool or spa). To heat the spa you need to set both valves to spa only. If the spa is filling up, the pump must be drawing some water from the pool.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Pentair Minimax NT Heater

    You and Jason may have tumbled on to the right idea. But, I still want to know what the heater thinks the temp is
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

  12. Back To Top    #12

    Re: Pentair Minimax NT Heater

    Thanks guys. That makes sense. Last night I played with the valves, when I do have the spillover turned off the heater loses pressure and of course wont go through the startup. The only way to keep pressure on the heater is to have the spillover valve open....

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    JasonLion's Avatar
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    Re: Pentair Minimax NT Heater

    That doesn't make any sense to me. Could you post a picture of your plumbing setup?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Pentair Minimax NT Heater

    Yes! I will try to get some pics at lunch and post them afterwards. Thanks again.

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    Re: Pentair Minimax NT Heater

    Here is my pic..more if needed. Any help will be appreciated.

    [attachment=0:7g0b7yiu]DSCN1526-2.JPG[/attachment:7g0b7yiu]
    Attached Images Attached Images

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    JasonLion's Avatar
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    Re: Pentair Minimax NT Heater

    Wow, that is scary. Is it possible to get another angle on that maze of pipe? I can't quite follow everything.

    I see two pumps, one three way valve, at least six ball valves, and what looks like four capped off pipe ends.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Pentair Minimax NT Heater

    Sure. Here is some other shots:

    [attachment=1:vwxp4w5r]DSCN1522-2.JPG[/attachment:vwxp4w5r]

    [attachment=0:vwxp4w5r]DSCN1526-2.JPG[/attachment:vwxp4w5r]
    Attached Images Attached Images

  18. Back To Top    #18

    Re: Pentair Minimax NT Heater

    The two red valves and the white one controls my pool jets and drain.

    The small white one controls the spillover. He put a circulation pump on there that I have no idea what it circulates. Up at the top (not in pic) is the blower.

  19. Back To Top    #19

    Re: Pentair Minimax NT Heater

    Another angle:

    [attachment=0:cbzli6ed]DSCN1523-2.JPG[/attachment:cbzli6ed]
    Attached Images Attached Images

  20. Back To Top    #20
    JasonLion's Avatar
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    Re: Pentair Minimax NT Heater

    I see three suction lines: the two red valves with a white valve between them that feed into the pump. One of those should be skimmer(s), one pool main drain, and one the spa main drain. If you try turning off one at a time you should be able to figure out which is which fairly easily.

    There are either three or four return lines: the line at the base of the filter with a black valve, the output of the heater, the column of pipe going up towards the roof, and another one near the heater feed from the small white valve coming out of the three way valve. Again, a little experimenting should reveal at least what some of those four lines feed.

    Right now water to the small pump at the bottom of the heater is turned off. The three way valve also appears to be set to have water to the heater turned off.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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