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Short cycle

Loop1 Member Posts: 13
This is no big deal, but I am really puzzled.With my old oil burner and thermostat combination the burner would on rare occasions fire up nicely and then cut off after about a 5 second burn. When that system needed replacing I got a new furnace (of a different brand) and put in a programmable thermostat, and the same occasional 5-second burn is still with me! Oil tank is in the basement, and I have a single-pipe feed. Any thougts has to how I can eliminate the short burns?


  • Weezbo
    Weezbo Member Posts: 6,232
    spend a dollar on maintenance ,

    invite an oil burner man over , make him a cup of coffee and ask him to give you some recommendations after its cleaned and tuned .based upon what he discovers .

  • Loop1
    Loop1 Member Posts: 13
    More info

    It started this short cycle the first year the new furnace was installed, and I have it cleaned and tuned each summer.
  • Weezbo
    Weezbo Member Posts: 6,232

    it could be something very simple such as tightening a fuel oil line brass "B" nut .

    or, it may be because of a charateristic of the burner guns temperature with an entrained "Air" bubble after shutdown .

    mind me asking what the name is on the burner?
  • Loop1
    Loop1 Member Posts: 13
    Burner info

    It is a Beckett burner and a Honeywell controller. Furnace baseboard hot water type, no zones.
  • Weezbo
    Weezbo Member Posts: 6,232
    a couple crescent wrenches

    or a crescent and pair of small grips , and just see if there are any fittings leading up to the oil pump , that may be not quite tight .sometimes the thing is to take a clean white napkin and press it against the fittings at each connection prior to doing any tighening .

    if you see any wet spot on the napkin then that is more than likely the source of the minor technicality . because oil has a distinctive odor , if you see any sign of oil the smell test will be a confirmation that you have a very small leak .
  • icesailor
    icesailor Member Posts: 7,265
    Occasional short burns.

    Check the heat anticipator on the thermostat. Move the "pointer" in the direction of "Longer" which will be a change in number from say .04 to .06 or more. If it is a round Honeywell T-87 round thermostat with the mercury bulb, change it. Dispose of it properly.

    I can explain better if you need but try that. It will usually fix it. That's on the assumption that when it does this, it starts cleanly, runs for a period and runs well. Then, shuts down for a period then starts up normally. It isn't misfiring. Like no ignition when starting. If it starts and only runs for 45 seconds, that's another issue. If it runs for 5 minutes, and stops, try the Thermostat setting.
  • Jim Davis_3
    Jim Davis_3 Member Posts: 578

    How do you know the burner is actually firing?  Does it lock out or does it relight right after it goes out?  Beckett does kill their spark after it is lit.  Possibly could be some air bubbles as other have said, from leaky fittings.  Does this happen all winter or just after it is serviced?
  • what the ??

    What the heck is a furance baseboard??
  • Weezbo
    Weezbo Member Posts: 6,232
    edited November 2013
    Jim ,

    I recall something similar happening with an outdoor tank that had a leaf in the tank.

    we see more vacuum leaks , or entrained air problems with short unexplained 5 second runs , one time a friend of mine could not discover why the boiler was behaving erratically,

    and quite a few other friends in the trade were exhausted with it as it always preformed flawlessly while they were on site ..

    it turned out that No seeUms ,a very pinner type of fly , somewhat the size proportion of a Gnat to a fly in comparison to the gnat , had taken up living in the boiler and short vent and just outside the buildings lower side of the vent during burn ..lol

    however , it produced a variety of fun and games ...and though not even similar to the concern here, goes to show, that even when we think there is nothing new under the sun ,we may not have seen it all...

    were it a commercial building , we would likely use a pump to fill and purge to the appliance , most homes the run is much shorter and not too many burner techs do much more than "Trick the eye" ...

    with pre purge it disguises some vac leaks if they are not showing on a given gauge.

    Tiger loop combos do an excellent job of it also and also provide a clue in the filter bowls reservoir of oil.

    on one job years ago , i had a very small piece of copper and a whole lot of clear hose , and we fired the boiler up and it ran properly never missing a beat , the thing was that i routed the hose away from being underfoot or able to be disturbed in any way , many folks were marveling that the oil did not completely fill the hose and that there were huge air bubbles captured in the lines on the fastened riser ,it is like that unless it is seen my someones eyes , explaining it to them some times just just lol...

    : ))

    well rather than go into air in the gun , specks in front of the fire eye , i went with some Graphic language : )

    Knida like my Snow Hat

    *~//: )

    LOOP1 ,

    here is a small quote out of Wiki ,


    New Zealand sandflies have a native Māori legend wherein "the god Tu-te-raki-whanoa had just finished creating the landscape of Fiordland, it was absolutely stunning... so stunning that it stopped people from working. They just stood around gazing at the beauty instead. The goddess Hinenuitepo became angry at these unproductive people, so she created the sandfly to bite them and get them moving"[5]

    These sand flies were able, according to another Maori legend, to revive the dead hero Ha-tupatu.[6]

    In moral philosophy, the nature of sandflies is used as an analogy for a particular implied inference, the "noseeum inference", where one fallaciously concludes that since one cannot see something, it therefore cannot exist.[7]


    Arrrgh... lol

    It is bit difficult to catch somethings and it could be like IceSailor is saying though i would go with some hefty build up of lint on a Tstat being something that might be a more likely cause. a service tech has his list of directives when he shows up and the T stats seldom overlooked.

    hope that helps.


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