Question about Lite On Laars Lite 2 Heaters: 250,000BTU MV Heater

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I have a Laars Lite 2 milivolt pool heater. The heater works fine when the temperature dial is set to a setting higher than the water temperature, but when the dial is set to below the water termperature the heater keeps cycling on and off.

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  • claude452 May 30, 2011

    This heater has an electronic control module. The temperature setting pot and the temperature sensing probe are connected to this module. The module is powered by the thermocouple and it switches the gas vulve on when the temperature is lower than the setting calls for. It is working fine when the temperature setting is higher than the temperature reading returned by the thermperature sensing probe, when the setting is lowered to bellow the temperature reading, the heater shuts off, but keepes coming on every few seconds. As soon as the main burner turns on, it shuts off.

    The defect is in the thermostat system, which is what I descibed above. I suspect that either the thermocouple is defective (tests so far have not been conclusive), or the electronic module. The electronic module is work over $200, so I don't want to replace it to find out that the problem is still there.



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I would suspect that the thermostat is bad...however to pinpoint the problem exactly you would need to test it with a meter...this is a bit harder on a millivolt system as the voltages are very low and harder to detect...
So the best way would be to just disconnect the thermostat and see if the heater still not, then the thermostat is the problem...replace that.... if it still keeps on cycling, then you will need to figure out what is causing it to cycling on and off...


Posted on May 30, 2011

  • D. Floyd Kolb
    D. Floyd Kolb May 30, 2011

    I would replace the probe (thermistor) before going with the is not common for the thermistors to go bad and cause this type of problem...



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