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New Stove Pipe Installation Help

Post in 'Classic Wood Stove Forums (prior to approx. 1993)' started by mashman, Jan 8, 2012.

  1. mashman

    mashman New Member

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    Hi all,
    I was given an old Suburban CoalMaster Coal/Wood burning stove (posted about it in the classic stove forum). I had the flue cleaned and now I'm ready to install. Seems pretty straightforward but I want to make sure I get everything right. I'm installing the stove in my basement. Previous owners had a wood stove down there but I haven't ever used one.
    I just bought the black 24 ga stove pipe, 2-24" straight pieces and two-90 degree elbows. I also bought some of that black furnace cement.

    I'm going to enlist the help of a couple of neighbors who have wood stoves if I can but I might have to go this alone so any tips would be appreciated.

    So I'm going to...
    Insert the crimped end of the 90 degree elbow into the stove, use four sheet metal screws to keep it in place (do I need to use the cement here as well?)
    Measure and cut one of my straight lengths of pipe to length (what is the best way to cut, I don't have any shears so I'm going to have to get some at the hardware store)
    Put the crimped end of a straight pipe into the non-crimped end of that elbow (now wait...I thought I've read that the non crimped end of the pipes should face down to avoid condensation running along the inside of the pipes)
    Put the crimped end of the other straight pipe (the one I cut to length?) into the non crimped end of the straight pipe.
    Connect the other elbow

    What did I miss? Should I use the furnace cement on all seams? Should I use sheet metal screws on all seams?
    Any tips would be greatly appreciated.

    Thanks

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  2. webby3650

    webby3650 Minister of Fire

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    You will want all crimped ends pointed down, act as if you were gonna pour water down the pipe and you wanted it to end up in the stove. You will want 3 screws in each pipe joint. No cement is required, this stove draws, so smoke shouldn't come out, if it does you got some problems going on. The new pipe will smoke a bit as it gets hot though.
  3. webby3650

    webby3650 Minister of Fire

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    One more thing, It's kinda odd to have 2 90's, what kinda set up you got going? Ohh, rear exit. Got it, sorry.
  4. mashman

    mashman New Member

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  5. webby3650

    webby3650 Minister of Fire

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    You can cut it with tin snips if it' s 24 ga. If it's any thicker I use a grinder with a cut off wheel.
  6. mashman

    mashman New Member

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    Ok...another question. The stove is being installed in the basement where there was a wood stove previously. There is a hole in the concrete wall and when we moved in it was covered over. I uncovered the hole and it looks like basically they had some stove pipe in the hole previously but cut it or something.
    How do I get the pipe from my stove through this wall? Should I pull out the pipe that is in there currently and just run my 90 degree elbow right through the hole? If so do I need to use the furnace cement to hold it there? Or do I leave this pipe in the wall and get my 90 degree elbow to fit into it, if I do I think I will need some sort of male to male adapter to go into both the uncrimped end of the elbow and this pipe in the wall.

    any ideas?
    Thanks
    I've included a pic of the hole

    Attached Files:

  7. begreen

    begreen Mooderator Staff Member

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    What is that white foamy stuff? Is it soft? It makes me a bit suspicious. The other issue is that we can't see if there is a thimble in there or is that just the concrete block webbing? To be proper, there needs to be a clay thimble cemented clear through to the chimney clay tile.
  8. mashman

    mashman New Member

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    The white foam looks to be that 'Great Stuff' foam spray, I'm thinking the previous owner sprayed it in there after they capped off the hole.
    Could that metal in the pic be the thimble? It does seem to be cemented on.
  9. webby3650

    webby3650 Minister of Fire

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    Can you get a pic of the inside of the hole? Or a description of what you see inside using a light?
  10. WoodNStuff

    WoodNStuff Combustion Analyzer

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    No, the metal would not be the thimble. The thimble in a masonry chimney must be fireclay liner. The reason for this is that the temperature where the horizontal thimble meets the vertical chimney flu is very high. The fireclay thimble is designed to handle these temperatures.

    I was wondering whether the metal ring that is still in the hole is the remnants of a sheet metal cap that was locked in using the Great Stuff foam. Either way, you'll want to get rid of the sheet metal ring and the foam.

    More pics are needed. Take a picture directly into the hole to see what the inner workings of the wall/chimney look like.
  11. bogydave

    bogydave Minister of Fire

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    Welcome

    Do a "test fit" before you screw it together to make sure everything lines up well.
    Then post a Picture so the stove pipe gurus can look it over.
    They helped me out
    I had draft problems,
    I got a much better draft with 2 45° just before the chimney connection & double wall stove pipe.
    A good draft is key to good stove operations & no CO getting into the house.

    The foam around the metal piece looks link a weather plug was in there, not a working chimney, no signs of heat on the metal. No way to lock the stove pipe to it. Don't look right to me.
  12. mashman

    mashman New Member

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    Ah thanks, yes the sheet metal was probably all just part of a cap. I will remove it and get more pictures when I get home from work tonight.
    Thanks a lot for the help. I appreciate it
  13. mashman

    mashman New Member

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    So I took off the sheet metal and peeled away most of the white foam and all there is is a hole in the wall. It's really hard to get a picture because it's so dark but basically it's just a hole in the wall that goes right into the flue.
    Do I need to install a thimble (or have one installed?)

    Thanks
  14. begreen

    begreen Mooderator Staff Member

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    Yes, you want a sealed smoke path from the stove to the chimney.
  15. WoodNStuff

    WoodNStuff Combustion Analyzer

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    You definitely want a clay thimble. The wall that I see in your photo, that's a basement concrete block wall? Is your chimney made of concrete block also? If so, when you look into the hole, what is the total thickness of the wall? Basically, I would like to know whether the basement wall provides the thickness of one side of the chimney.

    If you go to a brick yard and tell them you need a thimble, they'll likely cut you a piece of clay culvert pipe to the right length for your situation. You'll need to know the distance from the basement wall to the inside surface of your clay chimney liner.
  16. mashman

    mashman New Member

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    Yes, it's a concrete block wall, the chimney is brick on the exterior.
    So I was testing out the size and the uncrimped side of my 90 degree elbow is too big to fit through the hole. The crimped end fits perfect.
    Just curious, why can't I just get a coupling (male to male) of stove pipe and put that into the hole?

    I'm going to start calling around for a thimble but will the thimble and the pipe fit into the hole?
  17. WoodNStuff

    WoodNStuff Combustion Analyzer

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    For one thing there is foam holding in the bit of sheet metal ring that is in there. Foam burns. Second, the thimble area is a place where a high concentration of heat occurs because of the 90 degree bend and its close proximity to the wood stove. And at this point we have not even talked codes or best practices, etc.

    No, the thimble will not fit into the hole. You'll need to remove the remnants of the sheet metal and the foam. You'll need to make the hole larger to accept the new thimble with about 1/2" - 3/4" of space around the outside for mortar. It's not hard to do. A little bit of work and you'll know it's done right. You can use a hammer drill with masonry bit to drill a circle the size needed and then hammer and chisel to remove the pieces.

    You'll also have to shape the clay liner to accept the thimble. The thimble should not protrude into the interior of the flue, just flush with it. Use refractory cement for the thimble/flue joint. You can use regular mortar around the thimble to bond it to the other masonry.

    By the way, I'm not sure we touched on this but you have a clay liner in this chimney. Right?

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