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Crown Oil Furnace Short Cycling

Jeff_111 Member Posts: 4
Hello, I've got a 4 year old Crown oil fired hot water furnace thats short cycling. Its got 3 zones, basement, bedroom and main living area. The limits are set at 180 high and 160 low. The unit was just serviced a few months ago and it seemed to get a little worse after the service. I'm not sure if he adjusted the limits and made it worse. We've only owned the house for just a year so I can't give you an idea of how it was before. We've got one programable thermostat and 2 mercury thermostats. Also, whats the adjustment labeled "Diff" above my Hi, Low limits? Any info is greatly appreciated. Thanks.


  • How often is the unit coming on?
  • burnerman_2
    burnerman_2 Member Posts: 297
    what type zone valve??

    taco zone valve's heat anticipator's need set at .09 if u have a digitalal one be sure it is preset at that or get one that is compatible with zone vales not sure of h/w without going out to the truck to get lit. hope this helps royboy
  • Jeff_111
    Jeff_111 Member Posts: 4

    The unit will sometimes kick on and the burner will literally run for 3 seconds then kick off. Sometimes it'll come on for a minute and then kick off.

    So you're saying I need to set the little dial under my thermostat covers to .09? My dials show .18 to .5+. Or are you talking the valves that are down by the furnace that open and close each zone? I'm sort of a heat rookie here but I can fix pretty much anything with some guidance.
  • burnerman_2
    burnerman_2 Member Posts: 297

    yes sometimes u may not notice this if one of the themostats is calling for heat the burner will run normal but the one that is off will trigger a call for heat then go off try the .09 see if that helps royboy
  • Jeff_111
    Jeff_111 Member Posts: 4

    So i'm looking for that .09 on the zone vavle next to the furnace or on my thermostat? The numbers on my thermostat dont go that low, they only go to .18
    Thanks again, Jeff
  • kpc_14
    kpc_14 Member Posts: 38
    what type....

    of zone valve do you have on the boiler? What type of t-stat do you have?
  • Jerry Valentine
    Jerry Valentine Member Posts: 15
    Short Cycle

    I believe he actually meant that the anticipator on the thermostat should be set at .9 -- not .09. Also the "diff" setting on your aquastat is the number of degrees the water temperature will drop to re-start the burner after the high limit setting has been reached. For your settings, I would set the "diff" between 10 to 15 degrees. Most likely one of your mercury thermostats is going bad. When it happens, turn one of them all the way down until you find which one it is.

  • Jeff_111
    Jeff_111 Member Posts: 4

    I've got 3 Taco zone valves. We have 2 in my opinion really cheap Honeywell thermostats with the slide temp adjustment at the bottom and its nearly impossible to tell what temp they're set at the way they're designed, those are in the bedroom an basement. Then the main living area has an older programmable Honeywell thermostat, I have all the screws adjusted on the back the way the directions said. I opened the limit range up 20 degrees from 180 high 160 low, now its 180 high, 140 low. Thats seemed to help some. Thanks.
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