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Downsizing 6" woodstove to 5" flue liner and other issues

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by wvbrad, Jan 20, 2006.

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  1. wvbrad

    wvbrad New Member

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    Jan 20, 2006
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    Hello,

    I've been lurking for quite a while, and now I need some help! I recently installed a Sierra wood stove with a 6" outlet. My chinmey is used for our oil furnace, so I needed to install a liner. My flue is 6" x 11"(?) ID, and I thought I could drop in a 6" flexible liner inside the flue and use both fuels and they would both have separate chimneys.

    Well, things did not go as planned. I got most of the liner throught the flue with lots of pulling, but when we got most of it down, the top 10' section got pulled apart. We couldn't pull the rest of the 20' back out, so we removed the 10' top section and installed the liner to the stove. The stove is working fine, but the liner is partially blocking the pipe where the furnace vents into the chimney. Also, the flexible liner snakes up the chimney and surely blocks the furnace from venting properly. We only use the furnace as a backup, but it does come on in the early morning.

    Here are my questions: how bad is my current situation? Can I remove the 6" liner and replace it with a 5" liner reduced at the stove? I'm wondering how this is affecting my furnace- it seems to be drafting well enough, but will it cause damage to the furnace or worse, damage to the house/us?

    Thanks so much for the help!!!

    Brad

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  2. PAfluedoctor

    PAfluedoctor New Member

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    Brad,

    The short answers: Current situation is bad, yes remove the liner, no don't down size it to 5 inch, yes it could cause a problem with the furnace in multiple areas.

    Now a little explanation. IF I'm understanding you correctly you have an 8 x 13 flue with a terra cotta liner with inside measurements of 6 x 11. You tried to drop a 6 inch liner inside the tc to connect to your wood stove and then the oil furnace would vent around the outside of the stainless liner but inside the terra cotta in the same chimney. Upon trying that the stainless liner came apart in the chimney and it doesn't even reach to the top of the flue now. Yes??

    You need to remove the stainless - somehow, and start over. Try lowering a rope with a hook on it down through the inside of the stainless, hook it on the T and try pulling it up and out. You're not supposed to have a solid fuel appliance sharing the flue with another appliance. You're also not supposed to vent one around the outside of the other. You have created a situation where the oil furnace may not be able to vent properly and will push carbon monoxide back in the house and the wood stove could produce enough build up in the top section of the chimney, where the stainless fell apart, to block any furnace exhaust that made it that far from getting out the top of the chimney.

    Like I said, get the stainless out, hook up the furnace like it used to be and either build a new chimney for the wood stove or at least call a someone in your area who can show you the right way to do this. Try www.csia.org and see if they have any listings for your area. Depending on the actual size of your chimney it may be possible - MAY BE, to put two 6 inch liners in the current chimney. Good luck.
  3. Todd

    Todd Minister of Fire

    Joined:
    Nov 19, 2005
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    Lake Wissota
    Brad,
    They also make a 5.5" liner. I had the same problem getting a 6" liner down so I bought a 5.5" and it drafts great. But don't do this if your sharing the same flue with your furnace. Like the prior post said its bad!
  4. PAfluedoctor

    PAfluedoctor New Member

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    Just fyi - many times a 6 inch liner will fit inside an 8 x8 or 8 x 13 terra cotta if there are no major offsets or bends inside the current liner. However, liners for solid fuel appliances are to be insulated and when you add the extra room for the insulation it no longer works.
  5. webbie

    webbie Seasoned Moderator Staff Member

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    Loc:
    Western Mass.
    Pretty bad!

    You can get ann oval or even rectangle liner, but you cannot use the same flue for both those appliances cause it is not sized for both.....in other words, you'd need to be able to get two 6" flues down there.

    Even if we give you the benefit of 5.5", you'll never get two of them down!

    What they call 8 x 12 flues are usually about 6.25 x 10.5 ID.
  6. wvbrad

    wvbrad New Member

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    Everyone,

    Thanks for your help. I kinda knew that this wasn't exactly the correct way. What about using a 'power flue' for the oil furnace? I've heard of these, and you can supposedly vent them out a window? I could do this in my basement, but I don't know if it would be worth it.

    Thanks again.

    Also, did I understand correctly that downsizing to a 5" flue is not a good idea? What if I downsize it right from the stove???
  7. PAfluedoctor

    PAfluedoctor New Member

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    Don't downsize the stove or the oil furnace for that matter.

    Power venters are acceptable but be aware that they can also cover the side of your house with oil soot if there is a problem at some point. Save the money from that and put up a second chimney. Masonry or class A.
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