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Condensation or water leak from chimney?

titelines Member Posts: 2
I replaced the wood stove in my home with a small hot water boiler a couple years ago, I tied the boiler exhaust into the old wood stove chimney, since then I have had water dripping inside house and an ice dam outside. Any thoughts or ideas would be greatly appreciated. I am attaching a couple of photos.


  • Jamie Hall
    Jamie Hall Member Posts: 23,454
    Almost certainly condensation in that chimney. Is the chimney insulated? It should be, that close to the house. Even so, I'd bet condensation.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • DZoro
    DZoro Member Posts: 1,048
    Agree @ Jamie Hall, also looks like there is a water heater piped into the back of the boiler T? This would definitely cause condensation due to oversized chimney for just water heater going up when the boiler is off. The chimney may even be oversized with the boiler and water heater combined use.
  • Bob Harper
    Bob Harper Member Posts: 1,040
    The bullhead tee inside is upside down. This will create a male-up joint that will leak condensate. I see a mix of pipe. Rather than bullheading the water heater into the tee, it should have come in closer to the chimney through a wye or tee and it should be 4" not 3" per code. It appears you don't have your 6" clearance to the single walled connector but if that's a section of factory chimney then its 2" and you're ok. That factory chimney is run up along the side of the building so how are you getting an ice dam in the roof? It should be spaced 2" away from the nearest combustible. It should terminate 3' min. above the roofline and 2' above any point within 10' horizontally so the flue gases should not be close enough to condense on the roof. If that chimney was installed upside down condensate will leak out of the joints and also get trapped within the concentric space where the insulation is and rot the pipe from the inside-out. Recommend a level II inspection of the venting then run combustion analysis. You may consider replacing those draft hoods with double acting barometric dampers especially if they're killing the draft, which measurement was not provided.
    The vent connector is not properly supported. It is male down until it gets to that bullhead tee, which would tend to spill condensate on the boiler. If you're getting condensate inside see combustion analysis as the tee outside will catch the condensate in the chimney.
  • titelines
    titelines Member Posts: 2
    Wow, wealth of knowledge here...thank-you. I guess ice dam was not the proper description, I was referring to the ice build up on the ground under the insulated metalbestos chimney. I plan to do away with the hot water heater this summer and use one of the heat exchanger units with hot water boiler.
    I learned a lot from your responses. Thanks again, I'm sure you professionals must cringe when you see some of us diy'ers hack jobs.