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Existing Wood Stove Chimney Venting for New Pellet Stove??

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by dbhn, Aug 8, 2008.

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  1. dbhn

    dbhn New Member

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    I have an existing masonry chimney set up with a free standing wood stove with 8" vent stack entering an 8" hole in masonry. Wood stove pipe comes vertical out of stove, 45s, and enters masonry. The pipe runs the length the horizontal hole in the masonry and ends where it meets the flue. Hope that makes sense.

    I am installing a free standing pellet stove in the same location (Breckwell P4000 vermont cast) and have questions about the venting pipe. My plan was to run the pipe very similar to what is described above. T outlet on stove, vertical pipe for roughly 4', 45, horizontal run into flue with 4" to 8" thimble.

    My question is is this correct? I did not think I needed to run the steel vent pipe the full length of the chimney and out the top in this type of set up but I cannot find anything anywhere that confirms this. I thought you only needed to line the chimney when you have a fireplace opening, not a wood stove 8" hole setup.

    Any advice would be greatly appreciated. I have learned a lot on this forum in the last couple of months prior to getting my stove. Just signed on to get specific help getting set up.

    BTW, chimney is an external masonry with a debri cap on the top.

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  2. JPapiPE

    JPapiPE New Member

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    Pellet stoves are much more forgiving than wood stoves and only use a 4" pipe and the gases are cooler so much less protection is needed. I'm a wood burner and don't know that much about a pellet stoves, except installions are less strict and a much smaller pipe is required for flue gases. My guess is you don't need to line your chimney and may not even have to use your chimney as they may vent through an outside wall. I could be very wrong so wait for the knowledgeable pellet burners to give you exact details.
  3. DiggerJim

    DiggerJim Feeling the Heat

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    Correct, you can't share the flue with multiple appliances.
  4. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Since he says it will sit in the same place I don't think he is talking about burning two stoves. I think he is replacing the wood burner with a pellet puppy.

    As to burning a pellet stove into an 8" pipe, I burn into a six inch liner just fine, Simpson makes adapters to go from 3" or 4" pellet pipe to 8" Class A so somebody out there is doing it. What would concern me is how big the rest of the masonry chimney is going on up.

    Very possible the exhaust wouldn't be enough to ever get the tiles up to temp and a bunch of crud would always be condensing on them. That is a prime candidate for a four inch flex liner.
  5. pelletfan

    pelletfan Member

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    maybe we understood wrong, but two appliances into one chimney is a no no.
    Run the Pellet Stove pipe, diam. 3" all the way up to the top of your masonry chimney with a nice Cap. It's just a nicer installation and cleaning is a breeze that way too.
    my personal opinion.
  6. hossthehermit

    hossthehermit Minister of Fire

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    I'm doing basically the same, but it's a center chimney. Been looking and don't seem to find a thimble adapter to go from the 4" vent pipe to my 8" thimble. Any thoughts? St. Croix Revolution
  7. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Gotta know what brand 4" pellet pipe you are using first. Different brands don't fit together.
  8. dbhn

    dbhn New Member

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    Sorry for the confusion guys. I will be replacing the wood stove with a pellet stove. Pellet stove will be only appliance in that flue.

    BrotherBart, I am confused by what you mean when you say "exhaust won't be enough to ever get the tiles up to temp". What "tiles"?

    What I am trying to avoid is running the flex pipe up and through the chimney. Well, only if it is safe. Hooking up a flex pipe to another pipe in the center of my flue must be a real challenge.
  9. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Your chimney should be tile-lined. In other words, there are square or rectangular sections of clay "pipe" that are stacked in the chimney. Those are called tiles, and form the actual flue that the gasses pass through. The brick around that is just there for mechanical structure.

    Some older chimneys were bare brick on the inside, and that is a safety hazard, as bricks are not air-tight.

    Pellet equipment is so efficient that it should not be vented into a large pipe intended for wood equipment. Typically, on a 100kbtuh pellet boiler, I would not vent into a tile chimney unless it was 6x6 and fairly tall. Larger chimneys don't heat up as quickly, and can cause a draft problem, or build-up of ash.

    Running a flex pipe up is the safe way to do it. You can bring the pipe all the way to the breach, in most cases (since it's flexible), and connect right there. That gives you a properly-sized flue, and makes cleaning it much easier.

    Joe
  10. slls

    slls Minister of Fire

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    I read in the Quadra manual no larger than 6 inch diameter or 28 square inches. Using those specs 6 inch square if too large.
  11. stoveguy2esw

    stoveguy2esw Minister of Fire

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    mine is direct connected to a 6" round SS lined masoinary works fine, but if it had been a larger flue i would have done a 4 inch liner. 8" is really quite big for a pellet stove , remember the stack temp still needs to stay above 230F all the way to the top to prevent condensation , and a pellet stove's exhaust isnt gonna be as hot as a woodstoves is. for that reason, i'd recommend lining the flue with 4 inch as everyone else has already suggested.
  12. dbhn

    dbhn New Member

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    Thanks everyone. I will check out the width of my flue but it looks like I've got to run the flex pipe up. I believe my flue diameter is rather large.
  13. JPapiPE

    JPapiPE New Member

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    Not like the old days back in 02, when one just knocked out a window and ran their pipe to the outside and covered the hole with an old piece of tin
  14. mkk2424

    mkk2424 New Member

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    What is the problem, if any by venting a pellet stove out a chimney that vents a oil furnace. I bought a new small pellet stove and I vented it in my chimney in my unfinished basement where I had a small wood stove I used very little. I have the pellet vented about 2 feet higher in the chimney than the furnace and the wood stove is gone. I can't figure out what could possibly be an issue.
    I am not concerned about my local laws(this is MY house!) but perhaps a technical explanation as to why many manuals frown on having more than 1 heating appliance connected to 1 flue(chimney right?)
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