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Venting boiler room

malex Member Posts: 106
After spending some time winterizing the basement in a '37 cape and sealing all noticeable air infiltration points I was just wondering if there would ever be a need to vent the basment/boiler room to make sure there is sufficient supply of air for the boiler. WHat happens if the basement/house is too tight?


  • billtwocase
    billtwocase Member Posts: 2,385
    is this

    a 1937 Cape? If so, it is unlikely that you will get the basement totally air tight. What is your burner's firing rate, and square footage of your basement? How much "stuff " is in your basement? You may have what seems to be adequate, but if the basement is chock full from floor to ceiling, that does not count, and will be of no use for combustion air.  If there is any doubt, an outside air intake is always best. You will see dark insulation to start with, if there is a negative pressure issue
  • chapchap70
    chapchap70 Member Posts: 139
    Tight boiler room

    If there is insufficient air in the boiler room for the oil burner to operate properly, the boiler could soot up quickly which may cause a puff back. 

    If air is piped directly from the outside to the burner, you can eliminate this problem along with possible problems of dust/lint clogging up the burner fan.

    You can put louvers on the boiler room door to allow more air into the boiler room.  If your boiler has access to all the air in the basement, (no walled off boiler room) and the basement is under the whole house, you probably will not have the air issue. 

    I am aware of an instance where the oil burner fan was able to pull a slightly open basement door closed.  That was a severe case.

    If you are concerned about this, have a technician run combustion tests in different scenarios.  (basement door closed, while kitchen fans are running, etc.)  If the readings don't change, you probably don't have a problem.
  • malex
    malex Member Posts: 106
    basement just over 910 sqft

    Boiler room takes up a little over a third of it. The rest is laundry/ unfinished and empty but i will be refinishing it so I will need to close the door to the boiler room.

    I did find a lot of black insulation (looked like dirty wool) in the rim joist bay) before sealing them up with rigid foam and expanding foam.

    Im sure i won't get it air tight but still a big difference from before when it was leaking as a sill (3 inch gap in the window frame only sealed with fiberglass insulation. But maybe this is not a worry in this case. Will have the tech check it out next tune up.
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