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Boiler short cycle?

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dmk
dmk Member Posts: 23
in Thermostats and Controls
My oil boiler seems to be short cycling. Triple triple aquastat High/low is 150/190 and diff @10, boiler fires and shuts down when gauge reads around 170, then turn on again 10 seconds later rarely getting up to the high set point. Would this indicate a bad aquastat? I'd say maybe the gauge is bad, but that doesn't explain the short cycles

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  • Paul48
    Paul48 Member Posts: 4,469
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    He didn't say the make, but Honeywell triple aquastats have a 10* hi-limit differential preset. The adjustable differential works around the lo-limit.
  • dmk
    dmk Member Posts: 23
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    It is a honeywell. Not sure what the function of the diff is. Can u explain? House is approx 2k sqft, boiler is Burnham RS-110, 1st floor and 2nd floor zones with internal coil that feeds dhw storage tank. This is my 2nd winter in this 25 year old house, so it's all fairly new to me. Would the diff be on 10 for efficiency?
  • dmk
    dmk Member Posts: 23
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    Would a smaller nozzle with same spray pattern help with short cycling? On average, how many times would you expect a boiler to fire throughout the day? And does the boiler fire off of return water temp? Thanks for all the help in advance!

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