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Combustion Air

Paul_28
Paul_28 Member Posts: 113
in THE MAIN WALL
My boiler room is 11*6*7 Feet and without windows. I would like to provide combustion air to my gas boiler, without having a very cool room. Any ideas???

Comments

  • Robert O'Connor_7
    Robert O'Connor_7 Member Posts: 688
    Combustion Air?

    How many btu's is it? Depending on the structure, (loose-tight)it could be as much as 1 square inch per thousand btu's, two openings are required, one within 12" of the ceiling and the other within 12" of the floor. Having the correct amount of combustion air is critical for the safe operation of any gas fired apliance. An inexpensive way to accomplish this is to install automatic (electric) dampers (PROPERLY SIZED see above) and tie them in through the boiler circuit so they open when the thermostat calls and when the end switch makes it will then send juice to the burner and shut down (close) after the call for heat has been satisfied...Good luck!....Robert O'Connor/NJ
  • Paul_28
    Paul_28 Member Posts: 113
    It seems

    to be a vary large opening. The boiler is 85000 BTU net.
  • Robert O'Connor_7
    Robert O'Connor_7 Member Posts: 688
    openings...

    Yes, they are large, but we have yet to define the structure. (loose---tight)(or something in between)The openings are sized by the buildings characteristics and input btu's, it is possible they could be half that size..Robert O'Connor/NJ
  • Ken_8
    Ken_8 Member Posts: 1,640
    It is entirely possible to use no outside air...

    Provided the interior space that connects to the boiler room is open to "free air" within the home. The size of the boiler is only a tad larger than many stoves!

    Bob is citing the strictest code interpretation. The most lenient one suggests no outside air is required if the room the boiler is in has the door open (or off the hinges) or perhaps fully louvered - and the rooms immediately attached to that - have NO doors, and/or are of adequate volume to meet code. A "normal sized home" is more than adequate - and has been in millions of home sin NJ for over 100 years.

    The code and chapter and verse I refer to is the National Fuel Gas code, Chapter 5.3.3 "All air from Inside the Building." The caveat being "Unusually tight construction," which is defined as having LESS than .35 air changes per hour.

    The only houses I know of with that tight a cosntruction are SIPS homes like the one I'm building for retirement!

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Robert O'Connor_7
    Robert O'Connor_7 Member Posts: 688
    Ken..

    Gotta get ya the new books. The newly adopted 2000 International Fuel Gas and Mechanical Code books (which I really like by the way) use specific language in (defining)interpreting the space. I recently (last year) took one of my Continued Ed courses and I gotta tell you was a major eye opener. This guy was giving us an overveiw of this topic and I could not belive what I was hearing. I too was from the "If it will fit, It will work" school of a bygone era but now I question most spaces. You see, in selecting makeup or combustion values many factors come in to play, more so than years ago. You now have exhaust fans in every toilet room, exhaust fans in the kitchens, dryers, ornamental fireplaces. All of these fans running (yes, in an extreme situation but..)are moving the air to the outside with nothing coming back in. The only air we get now is from under doors and through windows and if someone recently installed even crappy HD vinyl ones all bets are off. All these things are competing for the air and quite frankly if their atmospheric apliances will cause sooting and a potential CO (Oh no not CO again!)concerns. Robert O'Connor/NJ
  • Steve McCarthy
    Steve McCarthy Member Posts: 8
    Combustion air

    Many folks assume that if you duct air into a furnace/boiler room from the exterior of the house, that whenever the combustion appliance needs air, it will be delivered thru this opening. Not Always True! If the wind is blowing outside, air may be pushed in or pulled out depending on the wind direction. The wind will create a positive pressure on the side of the house that it blows against and a negative pressure on the opposite side. I suggest using a boiler that has combustion air piped into the appliance and also mechanically pushes the combustion products to the exterior of the house. Natural draft using a lined chimney works reliabily only in large volume, leaky houses.
    Steve / Starbright Energy Services
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