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Thread: Pentair minimax has Flame but no hot water, please help!!

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    Pentair minimax has Flame but no hot water, please help!!

    I have a Pentair minimax Plus 400 heater. It runs good, I have good flame and it stays lit. My problem is that the water doesn't come out hot on the other end. I'm out of ideas. Thank you for your help in advance.

    Nick
    15'x35' IG 16,500 gallons w/attached raised 18" spa continuous coping w/underneath spill and ledger stone wrapped, NPT mini pebble aqua blue w/2x pigment & abalone shell finish, 2"x24" travertine coping, 3x Jandy Color LED lights (2 in pool), Jandy Flo Pro 2HP VS pump, Jandy LXI (low NOx) 400K BTU heater, Jandy CL460 cartridge filter, Jandy AquaPure Ei SWG, Jandy Z4 automation with iAqualink and remote poolside PDA, 1,300 sqft Belgard Catalina paver deck with drainage, fire pit that matches the spa with travertine coping and wrapped in ledger stone, Elitewood insulated patio cover, Vinyl gates, back vinyl fence coming soon...
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    JasonLion's Avatar
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    Re: Pentair minimax has Flame but no hot water, please help!

    Welcome to TFP!

    A working pool heater will only raise the water temperature of the water passing through it by 1 to 10 degrees, with 2 to 4 degrees being typical. So it may not be immediately obvious that the heater is working even when it is.

    That said, if it really isn't working, then the bypass valve has probably gotten stuck in the bypass position. Heaters want a specific amount of water passing through the heat exchanger, so they require you to run more water than that through them and then have an internal bypass which lets any water above the ideal amount bypass the heat exchanger. If the valve that controls that gets stuck or broken you can occasionally get into a situation where all of the water is bypassing the heat exchanger, though that isn't common.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Pentair minimax has Flame but no hot water, please help!

    Thank you for the response. If there is a bypass how can I check?
    15'x35' IG 16,500 gallons w/attached raised 18" spa continuous coping w/underneath spill and ledger stone wrapped, NPT mini pebble aqua blue w/2x pigment & abalone shell finish, 2"x24" travertine coping, 3x Jandy Color LED lights (2 in pool), Jandy Flo Pro 2HP VS pump, Jandy LXI (low NOx) 400K BTU heater, Jandy CL460 cartridge filter, Jandy AquaPure Ei SWG, Jandy Z4 automation with iAqualink and remote poolside PDA, 1,300 sqft Belgard Catalina paver deck with drainage, fire pit that matches the spa with travertine coping and wrapped in ledger stone, Elitewood insulated patio cover, Vinyl gates, back vinyl fence coming soon...
    TF-100

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    Re: Pentair minimax has Flame but no hot water, please help!

    If the bypass is indeed closed, then the heater would shut off and not function. No water flow would prevent the unit from operating. The pressure switch should never allow the unit to fire if there is no water flow. Even if the unit did fire up with a bad pressure switch or something, it should over heat and start knocking and banging and probably melt down quickly.

    Take pictures of your heater and all valves. Then we could determine if a valve is closed, etc.

    What could be happening is if you have a spa, maybe the water is heating the spa water and then it's overflowing into your pool. Of course we don't know what you have as a setup. Just a pool or pool with a spa.
    Paul
    http://www.gastekservices.com 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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    Re: Pentair minimax has Flame but no hot water, please help!

    It would appear that the flow valve is defective, and possibly the pressure valve as well. The flow valve, which is installed behind the header where the inlet and outlet pipes are connected, contains a thermostatically controlled flow valve. This is described on page 30 of the following service manual:

    http://www.rhtubs.com/manual/minimaxPlus.pdf

    It appears that this bypass valve routes the water flow from the inlet to the outlet port when the heater is off. When the heater warms up, this opens the valve and sends water through the heat exchanger. I guess that even when the bypass is open, enough pressure is sensed by the pressure switch to fire your heater. The manual describes (on page 30) a test you can conduct with the bypass valve assembly to verify this is the problem. Here is a link to a replacement part (I think this is part #27 on the list):

    http://www.a1poolparts.com/-strse-1240/ ... Detail.bok

    I'd have a look at this and run the test and let us know how this turns out.
    38K in ground pool with attached spa. Current equipment: Easytouch 8 (521150) with IC-60 SWCG with web control by Autelis, 1x Pentair IntelliFlo 011018 pump (for filter), 1x Pentair 2HP WhisperFlo pump (for waterfall), 2X Pentair IntelliBrite 5G 12V lights, Pentair MiniMax400 NG Heater, Pentair SMBW2060 DE filter. Zodiac Barracuda MX8 cleaner on dedicated cleaner line. Lighting/home automation controlled by Insteon/ISY-99i.

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    Re: Pentair minimax has Flame but no hot water, please help!

    If the flow valve was stuck closed it should cycle on and off becasue the unit would over heat rather quickly. Does the unit cycle on and off or does it stay on constantly? Of course you have to be standing by it and watching it.
    Paul
    http://www.gastekservices.com 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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    Re: Pentair minimax has Flame but no hot water, please help!

    Quote Originally Posted by ps0303
    If the flow valve was stuck closed it should cycle on and off becasue the unit would over heat rather quickly. Does the unit cycle on and off or does it stay on constantly? Of course you have to be standing by it and watching it.
    I agree, unless there is something seriously wacky with this heater. Seems like it would be a good idea to not operate this heater until the problem is identified and fixed. A heater firing up without proper water flow is just asking for trouble.
    38K in ground pool with attached spa. Current equipment: Easytouch 8 (521150) with IC-60 SWCG with web control by Autelis, 1x Pentair IntelliFlo 011018 pump (for filter), 1x Pentair 2HP WhisperFlo pump (for waterfall), 2X Pentair IntelliBrite 5G 12V lights, Pentair MiniMax400 NG Heater, Pentair SMBW2060 DE filter. Zodiac Barracuda MX8 cleaner on dedicated cleaner line. Lighting/home automation controlled by Insteon/ISY-99i.

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