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Honeywell L8148A1017

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npeservices
npeservices Member Posts: 2
in Thermostats and Controls
I replaced a Honeywell L8148A1017, brand new. The high limit comes set at the highest setting. I follow the instructions on lowering the limit using a screwdriver to lift the high limit stop and set the dial to 180. The aquastat is running the boiler past my 180 setting up to 240. Is there a way to reset the high limit? The stop may have moved and I believe it is supposed to stay lock, hence using the screwdriver to lift it while making the adjustment??

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  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
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    Are you sure the sensor is properly installed in the well, or even working properly?
    If that's not it, you may have a bad one.
    steve
    Gsmith
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,834
    edited December 2020
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    I have never needed to "lift the stop" at the top of the limit temperature dial. I'm thinking you went the wrong way and are past the operating range of the thermostat portion of the control

    Does your adjustment look like this?


    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • npeservices
    npeservices Member Posts: 2
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    Yes it does. You can see the stop tab they tell you in the instructions to lift up while you turn the dial. The control is brand new from the heating supply store. The probe is installed in the well with the heat transfer paste. Any ideas which way to go with it?
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,834
    edited December 2020
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    @npeservices

    I have never needed to adjust the High limit Stop as indicated here.

    this "Stop" setting is to prevent anyone unfamiliar with the system from setting the high limit higher than the stop. This would be selected by the original part installer. I never used it because my customers would not think about trying to adjust that temperature. The room thermostat was the only adjustment they knew about.

    Please take notice of the "Pointer" in the illustration. it is positioned about 1/2" to 5/8" away from the dial with the approximate temperature numbers. in order to set the dial properly, you need to align your line of sight so you are perpendicular and level with the dial. Adjust the 180 so it is in line with the "Pointer". Now you are set at 180°F for the high limit. The High limit Stop does not need to be set as long as no one else touches the control.

    Without moving the "ADJUSTMENT STOP" just try moving the adjustment dial to a lower number and see if you get the high limit to shut the burner off at a lower temperature.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
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    I think you forget about adjusting the high limit and first determine the sensor is installed properly in the well, and that it's reading the correct temperature.
    If the water temp is 180° and the sensor is reading 180°, but the limit is letting it run past, get a new limit.
    Preferably an electronic one.
    steve
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,834
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    I do prefer the electronic ones. Honeywell more than the others. L7224U is my preference.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    SuperTech
  • tim smith
    tim smith Member Posts: 2,752
    edited December 2020
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    Could it be a miss wire with the new one?? We have pretty good luck with the L8148s. Other item is if pump not running, the aquastat may not be getting good flow around it before boiler climbs well past set point. Just .02 worth.
    T
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,834
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    tim smith said:

    Could it be a miss wire with the new one?? We have pretty good luck with the L8148s. Other item is if pump not running, the aquastat may not be getting good flow around it before boiler climbs well past set point. Just .02 worth.
    T

    Have you looked at the price of the L7224U. It is less than the L8148A and the L8124 and it does both. Less truck stock!

    I ran a burner repair business. Most of my competition was in the HVAC Install business. Repairs were a necessary evil for most of them.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics

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