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Thread: MiniMax nt 400 heater temp control

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    MiniMax nt 400 heater temp control

    My heater goes on and off due to Cell Temperature and not Water Temperature. For example, my spa is 88-degrees, I set the desired temp to 102-degrees. The heater comes on until the Cell Temp is 102, which takes only a few minutes, and then shuts off until the Cell Temp drops below 98-degrees. During this heat cycle the water temp may gain only one or two degrees. So it takes a long time to get the Water Temp up since the heater is working off Cell Temp. How do I get the unit to run off Water Temp and not Cell Temp? Where is the Cell Temp sensor located? I have an 18,000 gallon in-ground, salt water pool with a spa. The pool is controled by an Aqualogic controller and has a DE filter. The Kreepy Krawley seems to work ok and the unit shows "flow".

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    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: MiniMax nt 400 heater temp control

    I have the same heater but it's all manually controlled. I had a similar problem. I'd set spa temp and it wouldn't heat well. Setting the heater using the pool thermostat worked for me, because the water flow is controlled by the valves, not the heater. All it really knows is that the outlet temperature is above or below the set point and it works perfectly that way. I think there might be a way to plumb the two separately, but mine wasn't plumbed that way. Hope this will help.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    ps0303's Avatar
    Join Date
    Jul 2011

    Re: MiniMax nt 400 heater temp control

    So the heater is controlled by your Aqualogic controller. If that is the case then the heater has a wire going from the controller into the heater. All you really have to do is push the "remote" button on the heater to take it out of being controlled bu the Aqualogic. The remote light on the heater should go out. Then you can manually control the on/off and the temps via the heaters front panel.

    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.

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