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Extend flue Viessmann Vitodens 100-W

460Cobradad
460Cobradad Member Posts: 2
in Chimneys & Flues

Looking for info on extending the flue on my Viessmann. Currently goes through wall to the outside, apx 2' horizontal run. Right where it comes out I am installing a 16' deep deck and I know it can be extended but not sure how. Searching for info and all I can see is to use CPVC pipe to extend it. Is it really that simple? The Viessmann website is not clear on this and I can't seem to find an extension kit from them. Can I just use a 16' length of 4" CPVC for this?

Comments

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,212

    Is it currently a concentric vent (exhaust pipe within an air intake pipe) or single pipe?

    Use the same material and manufacturer of what is there now.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    460Cobradad
  • 460Cobradad
    460Cobradad Member Posts: 2

    Alan, it is the concentric type flue. Appears to be the 60/100. For the life of me I can't find any supplier in the US that sells extension pipes. Is this something that has to be purchased direct from Viessmann?

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,212
    edited August 16

    Viessmann used to sell vent material and then Centrotherm Innoflue came along and we couldn't get Viessmann anymore and they are slightly different - not compatible.

    The Innoflue catalog is here. I get my material from Cal Steam which is a Ferguson company.

    @GGross will have more current information.

    Screen Shot 2024-08-15 at 6.11.54 PM.png

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,562

    Cheaper and easier to go to a 2 pipe setup, PP for exhaust, PVC for intake

    To learn more about this professional, click here to visit their ad in Find A Contractor.
    PRR
  • PRR
    PRR Member Posts: 226
    edited August 20

    Cheaper and easier to go to a 2 pipe setup

    Agreed. The 1-piece fitting looks sleek, but was hard to source when I was re-furnacing, and expensive, and I'm way back in the woods in a hard-lived shack so I don't need beautiful pipes.

    That Viessmann furnace had a 2-pipe option. It looks like it needs a special plug which shipped with it but may be lost now. You need to boff another several-inch hole through the sill but modern battery tools make that play. The cost of two runs of pipe is probably much less than a run of coax pipe.

    My only concern is pipes coming out at deck level. If cut flush to the edge the condensate fog/spray may rot the wood. If run long to clear the deckwork it may impale the guy on the lawnmower. My back wall, I ran the pipes up the 3+ feet to head-height (I needed 2+ feet anyway for snow clearance but that was face-high). This was days when cheap white PVC drainpipe was kosher for purpose. The smoke pipe used to be shorter but over two winters I noted that it frequently fogged the soffit vent and another foot of pipe was cheaper than wet insulation or rotting rafters. I once pulled a squirrel corpse out of a radon vent so I put screens on both pipes (the ex-suet feeder and the white ring).

    FurnaceVent-2019.jpg

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