Chimney Condensation - What options for poor draft masonry chimney

tconway Posted By tconway, Dec 26, 2013 at 8:52 AM

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  1. tconway

    tconway
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    Dec 26, 2013
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    The symptoms are classic of a sluggish slow draft chimney; water from condensation and lots of it, very difficult to light filling the house with smoke, never gets really hot in the 500 degree range. The chimney itself is in the cold garage, goes through the attic and out the roof. It was built about 10 years ago and has 7" clay flue and was done according to building codes.

    Recently we bought a new stove (Woodstock Soapstone Progressive Hybrid), but I think that may have made matters worse because it is bigger and puts out more than the previous stove. It can take hours to get the chimney hot enough to prevent smoke from pouring into the house when the door is opened with the damper wide open.

    What options do I have.

    I could shoot for some major investment to get it working properly, or perhaps there are some less costly (in time and money) options I could try to kind of reach just a tipping point of adequate performance. And if I did go for a major investment, are there tests to see what would actually solve the problem.

    As is, it's not working very well...at all, I need to do something.

    Does anyone have any suggestions.

    Thanks for your help

    Tim
     
  2. mellow

    mellow
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    How tall is your chimney? I would suggest installing an insulated liner in it but without knowing the height I can't say if a 5" or 5.5" insulated liner will work, usually need around 20ft+ for them.
     
  3. tconway

    tconway
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    Dec 26, 2013
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    Woodstock Soapstone told me the stove was rated for a 6" flue. The chimney is about 22' from the floor of the garage, and the stove pipe enters the chimney at about 6' or 7' up from that. The Clay Flue pipe is 7" square interior and it's just a simple chimney built with chimney block and clay flue.

    Is there insulated flue that would fit inside that? Searching on the internet I could find little on what size insulated flue would fit inside any size clay flue.

    Thanks for the response.

    Tim
     
  4. Highbeam

    Highbeam
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    The days of the masonry chimney are short. They do not offer a good solution for venting the relatviely cold flue gasses of efficient appliances without these issues.

    I tore out a masonry chimney to install a modern class A insulated chimney and do not regret that decision.
     
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  5. mellow

    mellow
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    Chimney height is measured from the bottom of the firebox to the top of the chimney, if you only have 15 feet then reducing the liner to 5.5" will not work. Try sticking a paint can down your flue, it is about the same size as a 6" liner, but the problem is it really needs to be insulated which I do not see happening.

    You might have enough room in that chimney to bust out the 7" and install a class A 6".
     
  6. Hogwildz

    Hogwildz
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    Throw some kiln dried wood or non-pressure treated lumber scraps in there and see how she burns first.
    Might be as simple as the wood supply being too wet yet.

    As far as lining the chimney, you may be able to get a double wall insulated rigid down there.
     
  7. chimneylinerjames

    chimneylinerjames
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    Nov 26, 2012
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    Break out the flues and install a 6" liner with insulation. Or install pour down insulation. But you definitely need an insulated chimney liner. You might want to consider using a smooth inner wall liner or rigid liner to improve draft also. Going smooth wall will never hurt, it only will improve your situation.
     
  8. tcassavaugh

    tcassavaugh
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    I was going to suggest a small hot fire to get things heated up, then load her up.
     
  9. begreen

    begreen
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    Is there room enough to chase (box in) the chimney with a non-combustible insulation jacket of roxul?
     
  10. tconway

    tconway
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    Dec 26, 2013
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    Thank you for all the great replies. Progress has been made. I went and got a pickup truck load of wood that I KNEW to be dry and tried things out. Result? Happy to report that though I went through the expected slow startup, once things got going, it eventually reached about 750 degrees inside the stove and was burning nicely. I then put on some of the old questionable wood to test and sure enough, things slowed down again. I'm going to keep trying and testing.

    Couple other things.
    1. A friend of mine is a chimney sweep. He came over and said it was not likely the 3 bends from stove to chimney would be causing the problem as my setup is common with stoves that have no problem.
    2. He also said that with the 7" square flu, that a 6" metal liner with insulation poured around the corners, though not ideal, would help if nothing else was possible.
    3. Finally, the masonry chimney though old school also does work well with other folks I spoke with. In fact at my last house, that's what I had, and never had a problem, though the stove was primarily used with coal.

    Also, that little wax startup block (forget what it's called but it's something you pickup at Home Depot) that you break off a piece for starting, combined with small splits of one or two logs criss crossed really helped with the smoke all over the house at startup.

    Anyway, gettin' thar!

    Thanks again for all the replies

    Tim
     
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  11. Backwoods Savage

    Backwoods Savage
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    Sounds good Tim. As usual, dry wood rocks and takes care of most stove related problems. Keep this in mind now and know that you should already have next year's wood cut, split and stacked outdoors in the wind.
     
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