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Thread: Incorrect temp reading on Jandy LX heater...HELP!

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    Incorrect temp reading on Jandy LX heater...HELP!

    Hi,
    I have a 12 year old Jandy LX heater and have had very good luck with it until recently. When I fired it up for the first time this year, the temperature reading was 84 degrees Fahrenheit. I could tell it was wrong by putting my foot in the pool so I checked the floating thermometer and it read closer to 60 degrees.
    I cranked the desired setting to 104 (that's as high as it will go) and although the heater seemed to work fine, my pool is now around 75 and I can't get it any warmer because the thermometer still reads 104.
    I like it around 85 degrees.

    Have any of you experienced this issue? Any help would be appreciated.
    17K gal, gunite In Ground, 2 HP Jandy pump, 580 sq. ft.Jandy CL600CP cartridge filter system, Jandy LX Heater

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    Re: Incorrect temp reading on Jandy LX heater...HELP!

    Could be a bad temp sensor in the heater.
    Doughboy 12' x 20' Saphire semi-AG, Installed 2012
    Waterway 1.5 HP 2 speed, 100 sqft cartridge filter
    Aprox 7000 Gal, Full sun, 85K heat pump,
    TF-100 test kit

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    Re: Incorrect temp reading on Jandy LX heater...HELP!

    Quote Originally Posted by LI poolguy View Post
    Could be a bad temp sensor in the heater.

    Is there a way I can test it with my digital multimeter or is it one of those things you just have to swap out and see?
    17K gal, gunite In Ground, 2 HP Jandy pump, 580 sq. ft.Jandy CL600CP cartridge filter system, Jandy LX Heater

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    Re: Incorrect temp reading on Jandy LX heater...HELP!

    Check resistance of thermistor. It should follow the resistance given by a 10k thermistor chart.
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    Re: Incorrect temp reading on Jandy LX heater...HELP!

    Hope this helps...

    Temp sensor P/N: R0011800

    Factory Warranty Station for:
    Jandy/Zodiac, Pentair, Sta-Rite, Raypak (Rheem, Rudd), Polaris,
    and Paramount pool cleaning systems.

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    Re: Incorrect temp reading on Jandy LX heater...HELP!

    Great info, thanks very much to all. I'll let you know how it works out later this week when
    I've had a chance to dig in to this.
    17K gal, gunite In Ground, 2 HP Jandy pump, 580 sq. ft.Jandy CL600CP cartridge filter system, Jandy LX Heater

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    Re: Incorrect temp reading on Jandy LX heater...HELP!

    I finally got around to this and am reading 10.2 k Ohms from the disconnected sensor, which is probably pretty close. But when I reconnect it to the control PCB, the display reads 85 degrees and rapidly climbs to 111.



    Quote Originally Posted by Pool Clown View Post
    Hope this helps...

    Temp sensor P/N: R0011800


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    Re: Incorrect temp reading on Jandy LX heater...HELP!

    Is the heater running/flames on, when it jumps to 111? If so then it sounds like a water flow or bypass issue. If it's jumping to 111 and you don't have any flames burning, then it could be a bad temperature control.
    Paul
    Gastek Pool & Gas Services If you would like to provide a review of the help I provided, please use the following link to leave a review. Gastek Google review,
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    Re: Incorrect temp reading on Jandy LX heater...HELP!

    it does this without any flame at all. Do you think this is the part I need?

    http://www.parts4heating.com/Jandy-7...ly-p/7417g.htm
    17K gal, gunite In Ground, 2 HP Jandy pump, 580 sq. ft.Jandy CL600CP cartridge filter system, Jandy LX Heater

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    Re: Incorrect temp reading on Jandy LX heater...HELP!

    Quote Originally Posted by LI poolguy View Post
    Could be a bad temp sensor in the heater.
    Well, it turned out to be a bad temp sensor after all. It metered out okay, so that threw me, but I figured it was worth replacing for $70 before I went all in on a new control board.

    Thanks to all for your input.
    17K gal, gunite In Ground, 2 HP Jandy pump, 580 sq. ft.Jandy CL600CP cartridge filter system, Jandy LX Heater

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