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  1. #1
    Join Date
    Mar 2008
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    40

    Default Restoring wood-burning fireplace

    With an old, shot masonry chimney that is not safe, I would like to rebuild the entire fireplace using a steel thimble. What is used for the actual firebox area? Is there an insert that is rated for wood and can be installed into the masonry firebox area?

    After this, I assume one can install a steel thimble on top of the box and connect a steel 8"? flexible pipe system with chimney cap, similar to the kits I see for wood stoves.? What kind of insulation is required for the pipe? The existing chimney is large, square, and a straight shot up to the roof. Currently is has no chimney cap.

    Sounds like a lovely way to restore an old, grand wood-burning fireplace.

    Do the "thimbles" have flue open/close functions? I would like to avoid having to use a glass door cover...


  2. #2
    Join Date
    Jan 2008
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    2,203

    Default Re: Restoring wood-burning fireplace

    Since you'll want their services later anyway, find a local Chimney Sweep and see what they think. Some of them do inserts and any of them will know the local contractors who do this kind of work.

    Most of the cheaper inserts are very limited in fire capacity no matter their size so you'll need to know your intentioins for that ahead of time. Most do have dampers built in and direct pipe connections so no thimble is needed. You must use smooth-walled flue piping for wood so it doesn't create creosote traps.

    Now if you;re wanting to restore the original masonry fireplace then install a new flue liner you will need a thimble with a damper, the Mason which the Chimney Sweep recommends is the best one to consult for your options there. It may also be possible to 'drop in' masonry flue liner sections if the chimney was never lined, allowing you to keep the original damper (if it has one) intact and just rebuild the firebrick.

    Lots of possibilities await you but it all requires an on-site inspection so start there.

    Phil

  3. #3
    Join Date
    Mar 2008
    Posts
    40

    Default Re: Restoring wood-burning fireplace

    Thanks. Not sure I fully understand here. Is there a difference in what kind of liner to use for wood stoves vs. fireplaces? I know people with wood stoves who use triple wall pipe out the ceiling or use the steel flex ducting out the original chimney. My chimney is too shot to actually use safely, but I would like to avoid a complete liner situation. It is over 25 feet from hearth to roof. So I had thought the same ducting used for woodstoves would work in the chimney itself as long as one has a metal firebox in the hearth. Do I have this mixed up?

  4. #4
    Join Date
    Jul 2014
    Posts
    52

    Default Re: Restoring wood-burning fireplace

    ok to start off there is no thimble in a fireplace there is a fire box a damper a smoke chamber and a flue. A thimble is what goes through a wall to connect a stove or furnace to a chimney. Next there is no difference in the type of liner for a stove and a fireplace they are the same thing the difference is in the size. A fireplace will need a much larger flue in order to handle the large volume of air used by an open fireplace. Now what are you trying to accomplish are you looking to have an open fireplace for aesthetics or do you want something to provide heat? If you want and open fireplace you would rebuild the fire box and smoke chamber line the chimney with an appropriately sized liner and either put in a throat damper at the bottom or a top sealing one at the top. If you want heat you would slide an insert in the firebox and connect a smaller liner from the stove to the top of the chimney. This is a very basic description of your options if you have questions just ask

  5. #5
    Join Date
    Jan 2008
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    2,203

    Default Re: Restoring wood-burning fireplace

    Quote Originally Posted by cocteau3 View Post
    Thanks. Not sure I fully understand here. Is there a difference in what kind of liner to use for wood stoves vs. fireplaces?
    No, not exactly but you mentioned using flexible ducting which is usually corrugated and it is not suitable for wood burning. It's fine for gas stoves and appliances though since they do not create creosote. Wood burning requires smooth surfaces so they don't 'catch' the creosote and so they can be properly cleaned as needed. Speak with your local chimney sweep, they will have your best answers or know who does around there.

    Phil

  6. #6
    Join Date
    Jul 2014
    Posts
    52

    Default Re: Restoring wood-burning fireplace

    Quote Originally Posted by Mastercarpentry View Post
    No, not exactly but you mentioned using flexible ducting which is usually corrugated and it is not suitable for wood burning. It's fine for gas stoves and appliances though since they do not create creosote. Wood burning requires smooth surfaces so they don't 'catch' the creosote and so they can be properly cleaned as needed. Speak with your local chimney sweep, they will have your best answers or know who does around there.

    Phil
    I don't know where you got your info that corrugated liners are not suitable for wood but it is wrong. I am a csia certified sweep and i can tell you from lots of experience that cleaning is not a problem. There are many types and brands of flexible liners out there designed for wood appliances and most of them are corrugated in some way. I totally agree that the poster should get a sweep of a few in to give them quotes.

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