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Ice balls on chimney flashing?

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Hi. I looked up at my chimney today (25 F outside) and saw these ice balls by the chimney on the flashing. I’m new to the house this winter, and the chimney could be repointed and the chimney cap definitely is rusting a little. But I have no idea what this is.

We have a 15 year old furnace (just serviced) and new hot water heater, if that helps. It hasn’t rained hear in a week

Any help? Thanks in advance.

Comments

  • Fred
    Fred Member Posts: 8,542
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    The cap overhangs the chimney and with a warm chimney, condensation on the cap is running to those two corners of the cap and dripping down on the roof, where it freezes.
    daveinmassGordy
  • Gilmorrie
    Gilmorrie Member Posts: 185
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    Much more info needed, and photos of your boiler system. What does your boiler temp read? You, or someone, needs to measure the flue-gas temp, and adjust the combustion, accordingly.
  • Gordy
    Gordy Member Posts: 9,546
    edited December 2018
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    Agree with @Fred, not a big deal. Better on the roof than on the masonary where it will tear things up.speaking of that masonary if real looks a bit rough shape.
  • daveinmass
    daveinmass Member Posts: 6
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    Thanks for the help so far.
    I’ve attached another pic of the whole chimney for reference. Colder this morning.
    As noted, the furnace is gas and 15 years old. I had it serviced on Friday and the tech mentioned it has 85% efficiency.
    Here are the temp numbers from his check (not sure what they are, but here is how they are listed):
    Flue F: 290.8
    INLT F: 55.7
    NETT F: 235.1


    Hope that helps. Again thanks for the assistance.
  • daveinmass
    daveinmass Member Posts: 6
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    And yeah, the masonry has had a few patch jobs — already scheduled an estimate for May.
  • Gordy
    Gordy Member Posts: 9,546
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    I'd be concerned as to the inside of the chimney. Is it a clay tile liner? Or no liner at all?

    This could be the reason the masonary is in rough shape. The flue gases condensing are acidic, and will eat at the masonary.

    Back in the day of equipment with high stack temps it wasn't as much of a concern since the condensate would be burned off. With higher efficiency equipment with Lower stack temps chimney lining is a requirement to protect the masonary.
    kcopp
  • daveinmass
    daveinmass Member Posts: 6
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    Thanks Gordy. Looks like a clay liner, but I’ll add that to the list to make sure it gets checked in the spring.
  • Gordy
    Gordy Member Posts: 9,546
    edited December 2018
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    Clay liners are subject to acidic corrosion also. If they are misaligned flue tiles that leak the exhaust gase they will seep into the masonary. Also that chimney goes through the interior of your home. So if there is a breach in the masonary it could allow co into the living space.

    Not trying to scare you, but the exterior of the chimney is in poor shape due to the corrosive flue products eating away at the masonary. Probably most of the damage was done before a chimney cap was installed.
  • daveinmass
    daveinmass Member Posts: 6
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    Thanks. The inside (basement, attic) has been redone recently with cinderblock. I don’t think the exterior above the roof was touched.
    And we have plenty of (regularly tested) CO detectors.
    Gordy
  • Bob Harper
    Bob Harper Member Posts: 1,049
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    Pic of the top of the chimney? Also, its "masonry" guys. Yes, Gordo covered it pretty well.
  • daveinmass
    daveinmass Member Posts: 6
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    Hi Bob. Attached is a pic of the top of the chimney from a few weeks back. I’ve got a replacement, stainless steel cap—just arrived and now I’m waiting for the weather to be warm enough during the day to do a swap.

    But yeah, you can see the masonry grout needs some work.
  • Gordy
    Gordy Member Posts: 9,546
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    Some time if you want to do it right in nice weather. The concrete cap should overhang the brick about an 1 1/2” all the way around. This helps keep rain, and the condensate from running down the brick which will absorb the moisture, and deteriorate the mortar, and brick.
    Bob Harperdaveinmass