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Thread: Extending the range of my heater so it controls down to 50F

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    gtemkin's Avatar
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    Extending the range of my heater so it controls down to 50F

    I live in cooler climes and my wife was interested in swimming with a wet suit during the winter, but 37 degree water was just too cold for her. My heater manual says it controls from 70F to 104F but those temps would be pretty pricey over the long term so I put about a 10K ohm resistor inline with the temperature control pot and with a little time dialing the knob to that perfect point, I'm maintaining 50 degrees very well.

    I have a Jandy Lite2 250Kbtu millivolt model. Not sure if others can be so simply modified.
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: Extending the range of my heater so it controls down to

    You could be damaging your heat exchanger by running it at these lower temps. You might want to call Jandy and check on the following.

    A very long time ago we were taught to never use a heater as freeze protection because at lower water temps condensation forms on the heat exchanger. The process of burning off the condensation repeatedly fatigued the copper fins in the exchanger to the point that they no longer effectively exchanged the heat. You could test if this had happened by opening up the heater and running a screwdriver across the exchanger and if the fins easily folded over it was shot.

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    Re: Extending the range of my heater so it controls down to

    Quote Originally Posted by carolina pool
    You could be damaging your heat exchanger by running it at these lower temps. You might want to call Jandy and check on the following.

    A very long time ago we were taught to never use a heater as freeze protection because at lower water temps condensation forms on the heat exchanger. The process of burning off the condensation repeatedly fatigued the copper fins in the exchanger to the point that they no longer effectively exchanged the heat. You could test if this had happened by opening up the heater and running a screwdriver across the exchanger and if the fins easily folded over it was shot.
    You sir are correct. Unless you are heating with closed loop boiler with a water to water exchanger it is not a good idea to maintain temperatures less that 70.
    20X40 30,000 gallon gunite pool

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    gtemkin's Avatar
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    Re: Extending the range of my heater so it controls down to

    Very interesting! I have noticed the flue generate quite a lot of white steam for the first couple of minutes until the unit has warmed up. Similar to a car exhaust on a cold day. That must be the "burning off" of the condensation you folks mentioned. Darn, guess that's enough of that.
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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