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Is my boiler short cycling?

My oil fired boiler gets up to heat fine. Typically takes 50-65 minutes to heat the house depending on the delta T. Water does not surge and does not need to be replenished to often. However after it has run for that initial time it will turn back on a minute latter for a minute or two, and does this two or three times, on then off, on then off. I had it overhauled in January and the contractor at 2 Rivers did a very thorough job cleaning all the parts of the boiler and adding an anti corrosion solution to the water.

When the boiler is running, the psi gauge reads just under 2 psi.

Any idea why it does this?


  • Jamie Hall
    Jamie Hall Member Posts: 21,547
    Probably normal

    if it is doing it just at the end of such a long run, you've probably gotten to the point where all the radiation is hot, and not condensing quite as fast as the boiler is making steam -- so the pressuretrol is shutting off the burner (as it should) until the system condenses some steam and lowers the pressure, then the pressuretrol turns it back on.

    Now if it were to do that all the time, that would be a different story.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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