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Puff back

Rjbellezza Member Posts: 4
Is it normal for the damper to want to push out into the room when the boiler first fires? I recently got my boiler cleaned and now the damper pushed out into the room and now having a puff back. What causes this?


  • Zman
    Zman Member Posts: 7,001
    That doesn't sound safe. What model boiler? Can you post a video of the problem?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Rjbellezza
    Rjbellezza Member Posts: 4
    I don’t think you can post a video or if you know how can you let me know. It is a slant fin intrepid boiler. 
  • Zman
    Zman Member Posts: 7,001
    I think you can either attach one or post a link. I have not tried it but others have.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    EBEBRATT-Ed Member Posts: 10,355

    It's normal for the damper to swing or move when the burner lights. However if it sounds like the damper is smashing or violently banging you probably have an issue especially if it did not do it before.

    If you having this issue you probably need to call your service company back.

    Did they test the burner with an electronic analyzer?
  • Gilmorrie
    Gilmorrie Member Posts: 147
    Is this gas fired? Does is seem like delayed ignition? If a gas pilot is separated much from the main burner, then the firebox fills with fuel before it lights, causing a whoosh. We need more info.
  • Rjbellezza
    Rjbellezza Member Posts: 4
    This is an oil boiler. 
  • ChrisJ
    ChrisJ Member Posts: 11,978
    Shouldn't that damper have a counter weight on it, and I thought oil burners didn't usually use double acting barometrics, aren't those only for gas?

    @STEVEusaPA You'd know best on this.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • mattmia2
    mattmia2 Member Posts: 3,991
    That looks like some sort of a delayed ignition issue. My mostly uneducated guess would be that the mixture is way off.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,322
    Can't really tell from the video, but all the above advice is correct. It's not double acting, just an older barometric that should probably be replaced. If it opens out and gets stuck, that could be a problem too.

    Does the burner have pre-purge?

    Seem like too much air, causing a delayed ignition like @mattmia2 stated. Could also be electrodes out of adjustment, or improperly bled oil line/filter after service.

    Get them back out there like @EBEBRATT-Ed stated.
    Did they leave a printout of the combustion test?