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RayH Member Posts: 90
I have a customer with a Pensotti boiler and Riello oil burner. Very  rarely it wont fire on the 1st call for heat. It will fire the 2nd time and run just fine.  This is rare and always comes to temperature and has been heating fine for years. Occasionally while running it will miss fire and sputter but heats fine. Even after a tuneup. The boiler is 10yrs old. CO2 are 11% it has an oil filter at the tank and an additional spin on filter by the burner. Baffled???


  • pecmsg
    pecmsg Member Posts: 4,385
    Pump pressure?
    2 filters why?
  • RayH
    RayH Member Posts: 90
    The house was like that when purchased 
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,373
    edited May 1
    Two filters are fine, even recommended. Probably a slight vacuum leak. Is the entire fuel line system gravity, or are parts under vacuum.
    Do you know how to check for a vacuum leak (or high vacuum if it's a total lift job)?
    If it is a vacuum leak, best to fix the leak. Or take the easy route and put on a tiger loop.
    If it's not a vacuum leak, you'll have to get into testing the components, specifically the coil for the fuel pump, checking for proper over fire draft, and dialed in combustion. Of course, all the other checking-pump, pump drive key, etc.
  • RayH
    RayH Member Posts: 90
    The tank and filters are on a level basement floor. Not sure how to check vacuum? Will check it out 
    HVACNUT Member Posts: 5,464
    Could be too much over fire draft on a cold start, but the misfire and sputter during the run seems more like a vacuum leak. But if it's one pipe gravity fed off the bottom of the tank, you should see signs of oil.
    Get yourself a Riello gauge set (Westwood T20) to keep it simple. To check pressure, remove the priming fitting. To check vacuum, remove the 5/32 Allen nut in the pump cover.