Lochinvar Solution Temperature Settings

Discussion in 'Boiler Forum' started by rpowli, Dec 9, 2011.

  1. rpowli

    rpowli New Member

    Dec 9, 2011
    We have a Lochinvar Solution running three zones with the following settings
    Set Point = 180
    Differential =15
    High-Fire Offset =7

    When the boiler first starts up, it goes on Lo-Fire for 120 seconds, then Hi-Fire until it gets to around 173 and then goes to Low-Fire. So far so good.

    If only one or two zones are calling for heat, Lo-Fire will continue on until 180 is reached, then burners shut off until temperature drops to 160-165 and the the burner comes back on at Lo-Fire (not High-Fire even though it is well below the 7 degree High Fire Offset setting) ... maybe no big deal since this reduces short cycling. This continues until the zone(s) shut down and then system shuts down.

    If all three zones call for heat at the same time (e.g. first thing in the morning) Lo-Fire again kicks in at 173, but Lo-Fire is unable to increase the temperature and in fact the water temperature drifts down until it stabilizes around 160-165 degrees. It stays this way for quite awhile until one or two of the zones shuts down, then Lo-Fire will eventually increase the temperature to 180. It then proceeds as outlined above.

    Just wondering why the system will never turn on High-Fire during a cycle once it goes to Lo-Fire. I would think that once the temperature drops below the High-Fire Offset value, High-Fire would come back on.

    Does anyone know how it is supposed to work?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Do you know what the return water temperatures are?
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  4. tray

    tray New Member

    Dec 9, 2011
    hvac tech
    west henrietta, ny
    Is your boiler a high eff with an outdoor sensor. With some boilers, water temp and outdoor temp figure into where the boiler fires and if high is even need for efficiency. For the boiler, it maybe more eff to run on lo fire for 10min than on hi for 5-8min
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