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Ice building on roof vent

cr250jb
cr250jb Member Posts: 6
Hey I have a Trane ac and gas unit in my upstairs attic I started getting ice around the exhaust pipe outside on the roof were the pipe meets the steel flashing. It would form a block of ice and then I would find water or ice in the attic I had the roof replaced last summer and it has never done this before until the roof replacement. The unit is about 12 years old. I had my heating and air service guys replace the stove pipe through the roof and the steel flashing I had a roofer meet us on site to make sure the flashing was put in and caulked properly. I will try to post some pics of the unit and piping.



Comments

  • Jamie Hall
    Jamie Hall Member Posts: 17,011
    Is the water causing the trouble inside the roof and below the flashing? Or outside? If inside, it may be condensation from the air in the attic on the cold pipe where it goes through the roof. Try insulating the pipe...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    HVACNUT
  • HomerJSmith
    HomerJSmith Member Posts: 1,362
    How about pictures of the outside above there roof line.
  • HVACNUT
    HVACNUT Member Posts: 4,184
    Although I've never seen that before, I agree with @Jamie Hall .
    You stated new stove pipe (B vent). What condition was the old flue pipe? Rusty and rotted?
    Why the external regulator?
    Also, I see the furnace isn't lying directly on the plywood, but it needs to be set on a non combustible base with X" clearance to combustibles.
  • Zman
    Zman Member Posts: 6,959
    edited October 2018
    I suspect that your flue gas is condensing in the pipe due to the furnace and vent being installed in an unconditioned space. This would have rotted out the old vent and is likely causing the ice being formed around the the vent termination now.

    What part of the country do you live in? Attics tend to be very hot in the summer and very cold in the winter. This greatly reduces efficiency of both heating and cooling.

    The workmanship on your furnace leaves a great deal to be desired. Unsupported gas lines, exposed romex wires and questionable combustible clearances for starters...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ratio
    ratio Member Posts: 2,918
    It looks like daylight at the downhill side of the flashing around the vent?
  • John Mills_5
    John Mills_5 Member Posts: 935
    Wonder if the roofers pushed the cap too far down on the vertical pipe as it exits the roof? Had that happen a couple times lately when customers have had new roofs put on. That greatly reduces fume exhaust and can cause condensation.
  • JUGHNE
    JUGHNE Member Posts: 8,924
    I have had roofers sit on the cap of a 5" B vent. :s
    Crushed down causing flame roll out, burning all wiring at the gas valve.
    Was a mobile home with separate outside door and combustion air. Wasn't noticed until the wiring shorted out.
  • cr250jb
    cr250jb Member Posts: 6
    Ok I will try to get some outside picks of the roof line,I live in North Carolina
  • cr250jb
    cr250jb Member Posts: 6


    Here is a pick of the roof line unfortunately it has not gotten cold enough to build the block of ice.



    Here is a picture of the ice around the old pipe.
  • Zman
    Zman Member Posts: 6,959
    I assume the H2O is dripping down from the vent? That is not normal. Is there high humidity in the attic? Maybe you should post the nameplate on the furnace. There may be something wrong with the installation aside from the sloppy workmanship.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • pecmsg
    pecmsg Member Posts: 2,304
    cr250jb said:



    Here is a pick of the roof line unfortunately it has not gotten cold enough to build the block of ice.



    Here is a picture of the ice around the old pipe.

    Bathroom exhaust piped to the attic only.
  • Zman
    Zman Member Posts: 6,959
    That would do it....
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • neilc
    neilc Member Posts: 1,454
    flue condensate hitting the cap, and that's the low side where the drip drops off.
    If it was attic moisture how would it be geting there?
    it would present as frost inside the sheathing.
  • HVACNUT
    HVACNUT Member Posts: 4,184
    Is it the lighting and shadows in the first pic?
    It looks like a kind of repair or damage across the width of the pitch at the same height as the chimney.
  • Jamie Hall
    Jamie Hall Member Posts: 17,011
    neilc said:

    flue condensate hitting the cap, and that's the low side where the drip drops off.
    ...

    Has to be -- that's a classic picture! That may be really hard to cure.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • cr250jb
    cr250jb Member Posts: 6
    Hey thanks for the post everyone. The bathroom exhaust is piped out of the roof on another part of the roof. The pick were you see the ice is the old pipe and steel flashing and it would drip back down in the attic. I had the pipe and the flashing replaced and sealed,but the other night we had frost and I saw some drips in the attic I have a bucket under it now. The roof picture that looks like a repair is just frost on the roof. I will try to post some pictures of the name plate in the next couple of days.
  • cr250jb
    cr250jb Member Posts: 6
    Also we had ridge vents on the old roof and had the same installed on the new roof.
  • cr250jb
    cr250jb Member Posts: 6
    The moisture seems to be were the flashing and the pipe come together I have never seen it drip from the cap.