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short cycling

pjnick Member Posts: 18
just had my return cleaned out as well as the boiler had a new main vent installed 3/4 inch I have a single pipe steam boiler with a honewell pressuretrol the main is at 1 1/2 psi the diff is at 1/2 psi and the boiler is still short cycling any Ideas one thing that concerns me is the location of the main vent it is ride before the drop on the return is that right ? the boiler runs fine for 10 to 15 minutes everything gets warm but then it shuts down and starts right back up again in less than 2 minutes and continues to do that goin Crazy here !!


  • Jamie Hall
    Jamie Hall Member Posts: 23,419
    Do I take it from your comment that "everything gets warm" means that the radiators are pretty well warm across? And then the boiler shuts down? To be expected -- but it does suggest that the boiler is wickedly oversized for the load.

    What is the total EDR of the radiation, and what is the rating of the boiler, again in EDR?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Fred
    Fred Member Posts: 8,542
    Also, do you have some of the radiators closed off? If the boiler is over-sized, it will short cycle, at some point but you are compounding the problem if you have radiators shut off. Even if the boiler is properly sized for the EDR, closing radiators will create an over-sized situation.
    EBEBRATT-Ed Member Posts: 15,607
    The boiler is most likely going off on low water cut-off or steam pressure. You need to find out which one. Watch the water level. Is it bouncing? Is your pressure gage showing steam pressure?

    You can most likely here the switch inside the control open and close if you listen closely

    as @Jamie Hall & @Fred pointed out you should check the boiler rating against the connected load.

    You may be able to down fire the boiler if it is oversized. This can only be determined by a COMPETANT professional