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Laas mini-therm ll

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seeker1256
seeker1256 Member Posts: 4
in Radiant Heating
Model JVT160NDLS, mfc date 08/2003..



Having is little issue with the unit , started  on tailend  of last season, did not fix issue , now its fall/winter months i need to resolve this issue any help would be greatly appreciated , My unit keeps shutting down after 2 or 3 burns, I thought it was thermo coupler , did replace it , still same issue, I also replace the thermo switch, which I had to reset a few times last year, pretty expansive themo switch, after it quit on me last and the boiler told me I could do that if it happened again. this issue of the whole thing shutting down abruptly  during the burn cycle, I cannot figure out, I have pressure valve that id leaking , that will be replaced, also feels like that my expansion tank is full of water, should it be?, looking for help to get this resolved, We do not have a Laas dealer or a service depot here, just general boiler techs



Thanks    

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  • Zman
    Zman Member Posts: 7,569
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    Some laars

    Some Laars boilers of that vintage had electrical gremlins. The one I experienced was having trouble with high and low fire. The cause was the zip ties on the wiring bundles were really tight. This caused interference and control malfunction. Loosening the bundles might be worth a try.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Slimpickins
    Slimpickins Member Posts: 339
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    check heat exchanger

    Get a mirror and flashlight and check your heat exchanger. Chances are the boiler isn't piped correctly and is without boiler protection from cool return temps. 
  • seeker1256
    seeker1256 Member Posts: 4
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    Laasmini-therm ll

    will ,look into those option as mentioned , how ever the question also remains of the presure tank, seems like its full, when I tap on it, it does not return a hallow empty sound, intead it feels like its full, should I unmounted this after sutting the valve off and drain it, to begin with should this expaansion tank  be full of water ?, also cold the as valve be defective, is ther any way of checking this, I know the valve are expansive

    Thanks

      
  • Zman
    Zman Member Posts: 7,569
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    Expansion tank

    Your pressure valve sounds like it is working fine. What does your pressure gauge say? When the tank is bad there is not place for the expanding hot water to go. It goes out the valve, as it should.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • seeker1256
    seeker1256 Member Posts: 4
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    Laas mini-therm ll

    THe pressure gets up to 20 psi, I did drain some water from the system, the valve is not leaking much, how ever sould I be draining the expansion tank, which was replaced 1.5  years ago.
  • seeker1256
    seeker1256 Member Posts: 4
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    Laas mini-therm ll

    I did replace in pressure valve and a micro temp switch, tried to clean the heat exchanger to best I could, it was a little dirty, put it all together , fired it up and still have a same issue , after a 2 cycles the unit shuts down, abruptly  and takes the pilot light out as well, I tried lighting the  pilot light right away, It take s few tries before the gas flows and lets me light the pilot light .

    Any more suggestion in regrads to my delima, shoiuld I be emptying the  pressure tank ?



    Thanks
  • Zman
    Zman Member Posts: 7,569
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    2 Problems?

    It sounds like you have a failed or incorrectly pressurized expansion tank. You should be able to pull the tank, charge it with a hand pump to you system pressure and reinstall it. If the tank wont hold pressure, replace it.

    The second problem sounds like a thermo coupler issue. Does the pilot flame pull away from the thermo when the main burner fires. It sounds like it might.

    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
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