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Flue Questions and Air Supply (not the band)

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by jenp4, Sep 17, 2008.

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  1. jenp4

    jenp4 New Member

    Joined:
    Sep 17, 2008
    Messages:
    7
    Loc:
    Southern Minnesota
    I am looking to purchase a St Croix stove from a dealer in my town who just recently started selling them. I am looking at either the Hastings pellet stove or the Greenfield pellet/corn stove. The dealer does not have the answers for my questions, and I have to know this information before I buy. I am hopeful that someone knows on this forum :)

    My biggest concern is how I plan to vent the stove once I buy it:

    I have a chimney that is lined with a stainless steel flue (I believe it is rather large in diameter-- somewhere around 8 inches across)-- I do NOT have a fireplace. Currently I have a wood stove in the basement that is connected to this flue. I will only use that wood stove if the power goes out and I cannot use my pellet stove. My woodstove is old-- at least 40 years (so maybe not air tight?). I was going to have an access cut into my flue on the first floor so I can place my pellet stove in front of the chimeny and use the existing flue. I would run a vent pipe up from my pellet stove about 3 feet or so to elbow into the flue. I was going to run a 5 inch in diameter painted stainless tube for the pellet stove vent. I was planning on transitioning from the 3 inch to the 5 inch vent somewhere behind the stove.

    I am getting conflicting advice on whether or not I can use my flue in the chimney since the pellet stove is forced air. I am hearing things about "draw" issues and advice on making sure my woodstove is shut tightly so I do not have smoke in my house from the pellet stove. Mostly people have been telling me to contact the someone else to get the real information since no one seems to have the right info over here.

    Also, I have heard conflicting advice about whether or not I need to run a tube into the chimney cavity (not in the flue) for a fresh air supply-- do I need this? My house is 100 years old-- old windows, new blown-in foam insulation-- does that affect a need for a cold air supply?

    Please help! I would really appreciate it. I know most people vent these out the walls of their houses, but I would like to use the chimney if possible.

    Thank you!

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  2. begreen

    begreen Mooderator Staff Member

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    Loc:
    South Puget Sound, WA
    I'm confused. Is the plan is to splice into the 8" woodstove flue? If yes, that's a no go. Can't do that. Also confusing it the plan to transition to 5". That is unnecessary and out of spec I believe for the stove. A better plan is to give the pellet stove a dedicated exhaust flue. Stick with 3" unless the vertical rise dictates going to 4".
  3. jenp4

    jenp4 New Member

    Joined:
    Sep 17, 2008
    Messages:
    7
    Loc:
    Southern Minnesota
    Yes, the plan is to tie into the existing flue in the chimney-- I was going to have chimney guy come out and pull the flue out and cut in a splice so the pellet stove could elbow into it (there is already a hole through the brick in the living room for this that is 5 inches in diameter because of an old woodstove I imagine). He seems to think there isn't a problem with this since the pellet stove burns a wood pellet and the woodstove would be used very, very infrequently and it also burns wood.

    I thought I have seen 5 inch vents for pellet stoves when they run vertically up out the house-- the three inch looks awfully small-- not very aesthetically pleasing.

    Could you explain why I can't tie into the woodstove flue, especially if it is never/hardly used (only emergency use).
  4. DiggerJim

    DiggerJim Feeling the Heat

    Joined:
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    Messages:
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    Loc:
    Northcentral Connecticut
    You can't have them sharing the flue because of the code issue. You won't get the permit signed off and the insurance company won't be happy. Just because you say you'll only use it during an emergency, they have no way to make sure that happens - so they make it against the rules. This is the same reasoning used for distance offsets from opening windows, doors, etc - you might say you'd never open that window when the stove's on, but you might.

    Five inches isn't a standard pellet vent pipe size - either 3 or 4" is generally used. Use 4 if the total length of piping is greater than 15' - personally, I'd use it regardless, extra draft capacity for not a lot of extra money.
  5. jenp4

    jenp4 New Member

    Joined:
    Sep 17, 2008
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    7
    Loc:
    Southern Minnesota
    When I bought the house, the gas furnace and the woodstove were vented into the same flue-- THAT I know is not up to code, so that is why I changed it. I was told that the different types of exhausts can't mix with the gas and wood in the same flue and that the cresote from the wood stove is an issue with a gas stove, so that made sense to me. But what I am wondering is the specific reason why I cannot run a wood pellet burning stove into the same flue as a wood burning stove. (The chimney restoration guy here says that I can do it since they are both essentially "wood burning").

    I just want to know the reason why it isn't up to code from those of you who have experience/knowledge that I don't. :)

    Thanks again!
  6. woodsman23

    woodsman23 Minister of Fire

    Joined:
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    1,352
    Loc:
    western southern tier of NYS
    You cannot do it because the pellet stove is a powered exhaust and will seep into the pipe and with any type of down draft smoke will come out your wood stove. Now if you want to do it right then simply pull the exhaust from the wood stove and cap it tightly. The run 3-4" pellet stove pipe to the opening in your chimney where you are putting the pellet stove. Then simply use a 5" to 3" (or 4") reducer pipe from the chimney to the pellet pipe this will work.

    Good luck.
  7. jenp4

    jenp4 New Member

    Joined:
    Sep 17, 2008
    Messages:
    7
    Loc:
    Southern Minnesota
    Thank you! That does make sense. I will probably switch from buying a freestanding one to an insert and just vent it out the side of the house (I'll build a wall/mantel for it) to avoid the chimney altogether.
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