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cfm of oil burner?

TomM Posts: 233
Is there an easy way to calculate the air flow in CFM of an oil burner mathematically?  Or a general 'rule of thumb'?


I understand that you could find the number of molecules in a gallon of heating oil multiplied by the nozzle size in GPM and the number of molecules of oxygen in a cubic foot of air times the stoiciometric air fuel ratio and all that jazz.........but is there a heating guy handbook easy method?

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  • Robert O'Brien
    Robert O'Brien Member Posts: 3,542
    1600 CFM/Gallon

    To that you have to add excess air,usually 25-50% depending on age/quality of burner. So,about 2000-2400 CFM/ gallon. Makes sealed combustion look pretty good?
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  • TomM
    TomM Posts: 233
    thanks Bob!

    Sealed combustion looks real good from that angle.   Now its understandable why my 3000cu ft basement constantly sucks air from every crack in the wall.


    I was looking at burner intake air boots for outside air intake.  Field's has one with a 4" duct requirement.  At 1500 CFM thru a 4" duct, the air will be flowing at 286 feet per second!  It seems like that will turn into a jet engine and take off into outer space, sucking in anything that walks by the side of the house.  I can't see the fan motor lasting too long with an air boot of 4" diameter.  Can anybody recommend these things?  Seems like a loud design.

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  • lchmb
    lchmb Member Posts: 2,997
    edited October 2011

    The Beckett air boots are 4" with a vacuum relief installed. I have installed many of them with 4"  and it solves so many problems. They do have a maximum length of run with elbows and If your cant get to the outside in this distance I would look at the fan in a can to help solve your issues..

    Duct length distance, a maximum of

    30 linear feet of standard duct pipe

    and two (2) 90o elbows. Subtract

    7' from the maximum linear feet for

    every 90o elbow added. Maximum

    linear footage will be less for flex

    duct. Consult manufacturer for

    equivalent lengths.

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