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Combustion Air System

SBoston Member Posts: 61

When we installed our new steam boiler, we also installed a Fields Control "Fan-in-a-can". It worked great until the bearings went and now makes a racket when it turns on. The unit is covered under warrantee but I can't get the installer to replace it and the company won't deal with consumers. I called a local pluming supply that is willing to sell me a new one, but if I have to pay for something, I would like to see if there is anything better on the market.

The current setup blows cold air into the basement when the boiler is running. This seems to make the basement very cold during the dead of winter. Is there a better setup for my Burnham IN-6? </span>


  • caught in the middle?

    sounds like a job for the BBB !


    there are various arrangements of ducting which have a sort of draft hood sticking out the basement window, and terminating just above the floor. they promise to only allow in the amount of air  needed as the boiler is firing.--nbc
  • Fan In A Can

    is usually a very good product,,, but when off in summer months, in a damp environment the bushings or bearings will fail.

    NB-C is referring to a drop-down(like a drain trap) affair, leading to the floor, then rising back-up again, then dropping back-down to terminate 8" or so above the floor. The idea is cold-air (being more dense) will not navigate above the lower portion of the trap as the warmer air holds-it , unless under a negative condition. This is usually done with perimeter-pipe.
  • Kenny Greene_2
    Kenny Greene_2 Member Posts: 15
    We have used Tjernlund

    with good success in commercial applications. The company also has good support. The combustion air makeup can be viewed at

  • SBoston
    SBoston Member Posts: 61
    Fan in a can

    We went the the BBB, but i learned very quickly that they are no help at all. With the new laws about makeup air i am surprised that there aren't more companies making new innovative systems. 

    I think we will need to buy a new fan in a can ( i think this time we will go with the CAS4jr.) and get it off the floor.  I think your right, the damp concrete can't be good for it.

    Thanks agian for your help!
  • D107
    D107 Member Posts: 1,849
    question on 'drop-down' trap-type fai

    (HO here) That sounds ingenius; any diagrams on this? I'd guess these are made up by the installer, not available as a unit.  So let's say the intake enters the basement at 7ft above the floor, 90el drops down to the floor, how high up would it have to rise again --to form an effective trap--before dropping to 8 inches above the floor?

    This would seem to keep cold air out of the basement, and air temp would be somewhat moderated by the ambient air impacting the (PVC?) piping, hopefully enough not to gel the oilon really cold days. I know fan-in-cans have a vacuum breaker that can let ambient air into the intake mix, but this drop-down is certainly better than just  having an intake enter the space, make a 90el down and hang a few feet above the burner.  Probably need some hanger supports.


  • question on 'drop-down' trap-type fai

    What I would do is drop-down your 7` into a trap(using 2-90s), then rise up about 4`, use 2 more 90s and drop-back down 8" or so above the floor.

    I also insulate(with a "sock-type") the cold (intake side) of this trap(no farther) to stop any frost formation there may be. Just use sheet-metal perimeter pipe & elbows,,, and remember to size according to your combustion-air requirements!
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