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Vitodens vent offset ???

Solarstar Member Posts: 82
Can I offset the coaxial vent for a short distance ( 2 feet maybe at 30 or 45 degree angle) in an attic. Therefore unheated cold space????? Cannot see this iceing since short distance and flue gases would remelt any condensate at next firing if it is long run from the boiler!!! Thanks Paul


  • ALH_4
    ALH_4 Member Posts: 1,790

    If you are within the allowable equivalent length, go ahead and use a couple 45's to make an offset. I have done it many times. Rarely does everything work out for a straight shot out the roof.
  • Brad White
    Brad White Member Posts: 2,393
    I would not

    I would follow Viessmann's recomendations to the letter. It has to pitch and what you describe may or may not create a trap.

    You are over-estimating the pre-heating potential of the flue gasses to the incoming air. You are assuming that there will be icing and are relying on a warm-up cycle to melt it. Don't do that, for the safety of you and your family. At best you are setting yourself up for reduced firing and nuisance trips. That is a notch above a week in a hyperbaric chamber and that is a notch above eternity in the permafrost.

    Not sure how you would do that offset in a short distance anyway, the only elbows they offer are 90's (87's actually). Might be a periscope of sorts, that kind of offset, but why impose even that?

    Make the vent think it is inside. If the run is that short, would it be that difficult to insulate it?

    My $0.02

    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • Perry_3
    Perry_3 Member Posts: 498
    Brad - they offer 45 degree elbows as well


    Viessmann does offer 45 degree elbows as well (you get them as a set of two). I can look up the part number if needed.

    Doing an ofset like this is not a problem as long as you work within the Viessmann recomendations.

    My system goes horizontal for about 10 ft, 90 (87) degrees up for 2 feet, and 90 (87) degrees out of the house. The pipe out of the house is at a 90 degree angle to the 10 ft horizontal run. It is about 2 feet higher to get well above the snow line.

  • Brad White
    Brad White Member Posts: 2,393
    Happy to be Corrected, Perry

    When I ordered ours, I did not see it listed and the use of them was a possibility. In the end it went straight up and out the back through the rim joist.


    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
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