Results 1 to 7 of 7
  1. #1
    if a customer has a 100K furnace married with a 40k water heater, flue pipe 6" b-vent 7' through utility room roof, and you change the furnace out to a 90+ direct vent furnace would you orphan the water heater into the 6" b-vent?

  2. #2
    Join Date
    Oct 2004
    Posts
    3,400
    Sure looks like a good chance for condensation inside of the 6".



  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,377
    The cose does allow it.

    A 3" draft hood water heater may be vented into a chimney haveing a 49 sq.in. area.

    49 is the max area.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    Jun 2004
    Posts
    956
    Here you have to change the liner

  5. #5
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,240

    7x rule

    NFPA 54 allows for up to 7x flue size. Doesn't make it a good idea. Codes do not guarantee performance.

  6. #6
    Join Date
    Jun 2000
    Location
    WYO
    Posts
    2,019
    We normally pull the vent,Revent per GAMA tables.Normally 4" double wall pipe, run pvc vents vertically too, install fire stops,new jacks, comb. air for water heater.We usually do sealed comb furnace. If not, comb air too for furnace.
    never say never

  7. #7
    Join Date
    Oct 2001
    Location
    Waterford Michigan
    Posts
    2,668
    You need a copy of the GAMA vent tables so you can look this stuff up and apply it to your existing conditions.

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