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Fireplace install> How far to run pipe?

Post in 'Classic Wood Stove Forums (prior to approx. 1993)' started by yankeesouth, Jan 5, 2012.

  1. yankeesouth

    yankeesouth Member

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    Ok…I’m confused about installing my mid-moe in an existing fireplace. Several people have said to run stovepipe the entire way up the chimney. Other places, (Fisher Installation guide [isn’t their mama bear basically a mid-moe] and Hearthstone site say it’s pretty much acceptable to run a pipe up until it enters the chimney. (hits terracotta or past the smoke chamber) Being this will be cabin use and used 8-10 weekends out of the year….ya think this is ok to do? I know the perfect world says to run pipe all the way to the top, but the perfect owner doesn’t have a few hundred $$ laying around to put into it. Chimney is solid, no interior cracks.

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  2. dougand3

    dougand3 Minister of Fire

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    All the way out would be best - 1. safer - no CO back drafts, less creosote formation 2. better draft - same size liner as flue exit keeps exhaust flowing better.
    If you go there on a winter weekend - you'll want heat quickly. Optimal draft will be needed.
  3. basswidow

    basswidow Minister of Fire

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    It will draft better and perform better if you run a liner all the way up.
  4. KaptJaq

    KaptJaq Minister of Fire

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    It is also a lot easier to clean the flue with the pipe going all the way to the top. If the pipe ends part way up the creosote from the top of the flue can fall between the pipe and the original flue liner. Usually the only way to clean it right is to remove the stove and clean the smoke shelf and everything else from the bottom. With a full liner it greatly simplifies the procedure.
  5. Jags

    Jags Moderate Moderator Staff Member

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    A short pipe into the chimney was called a "slammer". Many of the old smoke dragons were installed this way. Many had problems with creosote because of it. Many still run that way today. I don't recommend doing it this way. Pipe to sunlight if possible.
  6. KaptJaq

    KaptJaq Minister of Fire

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    A short pipe is called a "Direct Connect".

    A "Slammer" has no pipe. The front edge on the slammer insert is supposed to seal against the front of the fireplace forcing all air that is pulled up the flue to go through the firebox. The opening on the top of the slammer insert lines up under the opening of the bottom of the flue.
  7. Jags

    Jags Moderate Moderator Staff Member

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    Not gonna argue, but around here when a stove is stuck into a fireplace with a short stack, it is commonly referred to as a "slammer" install. I have never heard the term "direct connect" in this type of application. Maybe its a dialect thing from one region to another. Dunno.
  8. mellow

    mellow Resident Stove Connoisseur

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    Correct, a direct connect would be ok for this install, you would just have to keep an eye on creosote buildup and as mentioned you might have draft issues.

    If you go the direct connect route make sure and do a block off plate (soft or hard) for your damper to reduce chances of CO poisoning.
  9. begreen

    begreen Mooderator Staff Member

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    A slammer is when there is no pipe on the flue collar and the surround seal is expected to seal off the insert. This is no longer permitted. The OP is describing a direct connect or stubbed install which is still permitted, though often less satisfactory than a full liner.
  10. Jags

    Jags Moderate Moderator Staff Member

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    Not doubting the definition at all. And probably makes more sense than our regional naming convention. So...I will digress and still suggest a full liner. :p
  11. stoveguy2esw

    stoveguy2esw Minister of Fire

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    actually unless specifically stated a slammer or direct connect method is not the way i would go either. most common issue is "cross sectional"area.

    according to NFPA211 the flue (chimney) should meet the following conditions;

    (1) the cross sectional area of the flue shall not be less than the cross sectional area of the appliance flue collar unless specified by the appliance manufacturer

    (2) the cross sectional area of the flue of a chimney with no wallls exposed to the outside below the roof line shall not be more than 3 times the cross sectional area of the appliance flue collar.

    (3) the cross sectional area of the flue of a chimney with one or more walls exposed to the outside below the roofline shall not be more than 2 times the cross sectional area of the appliance flue collar.

    this said the cross sectional area of a 6 inch flue collar is 28.26 (3.14X9) (9 being "r"squared of 6 inches , divide diameter in half (3) then multiply by itself to get square) then multiply that sum (9) by "pi" or 3.14) so 28.26 is the cross sectional value of a 6 inch collar. so 2 X 28.26 is 56.52.

    in a square or rectangular flue you measure width by length (east west X north south) so a 10X 10 would have a cross section of 100 sq inches.
  12. yankeesouth

    yankeesouth Member

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    Well....sounds like I may wait for the cash to run pipe all the way to the top. Between CO2 poisoning, bad drafting, and creosote buildup.....sounds like the half pipe method isn't good. Thanks for the feedback once again. I was just curious about the install because of all the info I have been reading. Most on this board, who are probably more experts than the manufacturing experts, give real world applications to the pro and cons of things. Seems the consensus is half pipe bad full pipe good. Question answered! Thanks!
  13. begreen

    begreen Mooderator Staff Member

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    Sounds like a good plan. I would rank the options in this order: slammer -bad, direct connect -poor, full liner -good, insulated liner -excellent. That is unless this chimney has no clay tile liner or if any of the clay tiles are cracked or damaged. If that is the case, an insulated liner is a necessity. Regardless of liner, be sure to have the chimney thoroughly cleaned and inspected first.
  14. 72Rover

    72Rover Member

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    My first year with the VC Resolute, I only vented it one stove pipe-length up the tile lined flue, even though the fireplace's damper had been replaced with a steel plate. That was over three decades ago - when I didn't know any better. Smoke wants to stay hot and fast-moving. If it slows and cools down, like exiting into a nice, big and cold liner, you'll get amazing deposits of creosote. Used snap-together pipe all the way out the top ever since, that is, until last year.

    Since the individual sections were a pain to work with up on the roof top, last year I purchased a continuous coil of stainless steel pipe. Purchased over the web, it wasn't too dear. Just search for SS flue pipe and you can get the exact length you need.


    Cheers

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