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Flex liner vs stovepipe?

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by mj5001, Nov 11, 2011.

  1. mj5001

    mj5001 Member

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    Other than the obvious stainless steel advantage with a liner, I don't see why going with stove pipe up an existing chimney wouldn't be alright. I completely took out the damper (that was fun) so have plenty of room for maneuvering it.

    Of course there's a rain cap at the top and I can't imagine too much moisture getting in there but of course I'm sure there will some rusting in time.


    But for under 50 bucks compared to 300, it sure sounds like the way to go -- Menards has 6" x 24" pieces (24 guage) at just 3.99 each right now. (28.00 total)


    Why "shouldn't" I ?


    And WHY is insulating around it necessary? I can understand sealing it well near the bottom to keep any room air from getting out but I've seen folks insulating the whole thing, even when going into a chimney -- I thought actually the colder the pipe is, the better the draw.

    ?

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  2. shawneyboy

    shawneyboy New Member

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    On the colder pipe comment. The colder the pipe the more likely the gasses will condense and create creosote, (usually on start-up or fresh load). With a insulated pipe you are keeping it warmer, which keeps the gasses warmer, which increases draft.

    I think you are confusing colder pipe with colder outside temps. When it is colder outside your draft increases because the greater difference between the hot exhaust and the colder outside temps, but the draft is not increased because your pipe itself is colder. To the contrary if your pipe is warmer, and the outside air is colder, you increase your draft. That is why sometimes a cold start is difficult until you get your flue temps up.


    Shawn
  3. Dune

    Dune Minister of Fire

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    How often do you feel like changing the pipe in the chimmey?
    It MIGHT last two whole seasons, but I don't believe it.
    Nevermind the fact that it doesn't meet code, so if your house burned down, your insurance company would not be obligated to pay.
  4. mj5001

    mj5001 Member

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    Ok thanks.

    Now what kind of insulation should be used? I heard "rockwool"?

    Anything I can get at a Home Depot etc?


    And the stove pipe instead of liner? OK to do?

    I would think the stovepipe would last several years.
  5. mj5001

    mj5001 Member

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    Really? Doesn't meet code?

    I must be missing something.

    Is "stove pipe" different from "chimney pipe" or something?
  6. EJL923

    EJL923 Feeling the Heat

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    If you want everyones advice, everyone is going to say to spend the extra money on the stainless flex liner.

    There are a few reasons. I believe the stainless has better heat resistance. You ask yourself, but the black chimney pipe is closer to the stove. Yes, but the chimney pipe is usually in an enclosed area while the stove pipe is allowed to radiat to its surroundings. Rusting, another. The piece of mind of having a continous liner and no worries of the pieces separating. Over a long run, the sections at the top and screws will be supporting a lot of weight, depending on how its installed.

    Insulation. I have an interior chimney with stainless liner. The liner itself is not insulated, but the bottom block off is well insulated. That bottom insulation proved itself worthy during this past 6 day power outage. The past two burn seasons it was just a plain plate with gaps. I have already noticed a huge difference in heat retention. As far as the liner insulation, i probably would have done it with an exterior chimney, but i only clean the liner once a year and there is minimal creosote, so flue temps arent an issue. The chimney was in good shape also, if it wasnt, then insulation would have been a must. It is also sealed at the top with a plate.
  7. pen

    pen There are some who call me...mod. Staff Member

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    The concern I would have is if the reason for lining the chimney is that the chimney itself isn't in that great a shape (cracked tiles for instance), this is not the stuff to use to protect your house in the event of a chimney fire.

    the problem is in that environment there would be a big opportunity for condensation to form on the ouside of that pipe (during the summer, when not burning 24/7, when the stove cools down on a cold overnight) Over time, you'll get rust but you'd have no way of checking to see if they were still in good enough shape to withstand a chimney fire.

    The next thing, is if they didn't hold together and one rusted / broke it could block your flue while the stove is running.

    Running a piece up into the flue on an old school (pre-epa) insert into an otherwise healthy chimney is one thing. I just think there are too many risks to try saving that couple of bucks now for something that will need to be replaced every few years anyway. Spend the money now and be set and safe for life.

    pen
  8. mj5001

    mj5001 Member

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    Ok.

    Case closed -- liner it is.

    I didn't realize there was stove pipe and chimney pipe. Big difference.

    Anyway -- won't ask again -- will do the liner.


    Thanks.
  9. Dune

    Dune Minister of Fire

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    Single wall pipe is only legal from the stove to the first transition.

    S.S. flue liner is continuous, stove pipe is not.
  10. pen

    pen There are some who call me...mod. Staff Member

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    Never hurts to ask! Good decision.

    pen
  11. oldspark

    oldspark Guest

    Dont be afraid to ask any thing as long as you are willing to learn, the people on this forum dont bite (not too hard any way). :lol:
  12. begreen

    begreen Mooderator Staff Member

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    By insulation are you referring to packing at the top and bottom of the chimney? If so, you should be able to get some Roxul (mineral insulation) at HD or Lowes.
  13. sebring

    sebring Member

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    Stainless Steel will be cheaper over the long haul... Wont have to mess with it for a long time.... Wont rust... ect..
  14. Lynda Lee Malone

    Lynda Lee Malone New Member

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    Hello and this gave me great information for my own concerns! I have purchased this great Leda/Hannover K7.15 coal/wood stove to install in my family room....was given a pretty high quote to put in a flextube and cap off top and bottom. I too wondered about the flex vs. non....and worry about cleaning the flex....can it be cleaned yearly without fear of damage?
  15. Joful

    Joful Minister of Fire

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    +1.

    The pipe is insulated to improve draft (warmer pipe provides better draft), and reduce creosote, the deposition of which primarily relies on condensation. Insulated liners means the liner is wrapped in a blanket or other insulation, top to bottom. The Roxul used at the top of a liner is also aimed at keeping the pipe warm (reducing creosote, helping draft), whereas the additional Roxul many use at the bottom of the liner is to help keep warm air in the house, rather than in the chimney chase.

    All of these concerns should be secondary to the issue of meeting code, for the sake of insurance and future resale. Are you really willing to cut a corner like this over $300?
  16. Lynda Lee Malone

    Lynda Lee Malone New Member

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  17. Lynda Lee Malone

    Lynda Lee Malone New Member

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    Thanks for this reply....and no, the extra $300 would sure be well worth any risk...my main concern is with the type of flex tube....does it last through years of cleaning or need to be replaced every so many years?
  18. weatherguy

    weatherguy Minister of Fire

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    It should last a long time even with cleaning it once or twice a year.
  19. Lynda Lee Malone

    Lynda Lee Malone New Member

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    Thx...
  20. Lynda Lee Malone

    Lynda Lee Malone New Member

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    I also will need to retrofit the fireplace opening with metal...the same consultant told me that painted sheet metal would be fine, but as a "woman" I go for the Visual....and black metal seems not to appeal! Any suggestions...and what type of paint could I use without fear of off-gassing?
  21. chimneylinerjames

    chimneylinerjames Feeling the Heat

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    If you get a quality chimney liner, it will last forever. It will not be damaged thru normal cleanings. You do have to use special brushes for a flexible chimney liner. If you use a wire brush on the flex liner it will damage the liner and void the warranty.

    The stainless steel will handle chimney fires with no damage. I have personally returned on installs I did where they had a chimney fire, we cleaned the liner, inspected it and everything was fine.
  22. Joful

    Joful Minister of Fire

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    Hi Lynda,

    Black sheet metal is the standard for trimming an insert, but by no means a rule. I'm not familiar with the Hannover k7.15, and a quick search on Google did not turn up much.

    Can you start a separate thread so we can all discusss your concerns, without trampling on mj5001's thread? Perhaps the moderators can separate out these posts into another thread.

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