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13" Triple wall stove pipe

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

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  1. yogabill

    yogabill New Member

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    Greetings,
    Could not find much about this topic in a search so.....

    I am extending a customers stove pipe above the ridge line of the roof by another 2 feet to give her more draw on the stove. 13" triple wall is difficult to find (unless someone out there knows where to find some). A solution I am considering is to custom make a stove pipe reducer to allow me to extend the inner 8" stove pipe while closing off the outer two stove pipes. I assume that the only reason for the triple wall is for heat protection while the inner 8" actually connects to the stove for smoke release. Any input would be appreciated.

    thanks
    Bill

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  2. pen

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

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    The top of the chimney accumulates the greatest amount of creosote as it is because even w/ triple wall or insulated pipe it loses heat as it travels up. By extending it the way you are talking you are going to lose the insulation value of those closed air spaces in that pipe and make a creosote factory for her.

    I don't recommend it.

    Do you know the brand? If it's duravent this might be what you should be looking for http://www.amazon.com/dp/B002JL76QY...e=asn&creative=395105&creativeASIN=B002JL76QY

    pen
  3. 98dingo

    98dingo New Member

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    A chimney SYSTEM is designed and tested using only approved parts. You are taking a risk by modifying any chimney system. Your best bet is to try and find a label on a section and order the same type. Or if you can't find the info, the next option would be full replacement.
  4. DiscoInferno

    DiscoInferno Minister of Fire

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    If it's air-cooled (as it sounds like) then you aren't supposed to block the gaps between the walls. Airflow is part of the design. Majestic has a chimney like you describe, it's their "type S" or "S8" chimney. Not sure where you can buy it.
  5. humpin iron

    humpin iron Feeling the Heat

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    NOT spose to use air cooled chim for wood stoves
  6. yogabill

    yogabill New Member

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    Great answers and food for thought. From what she tells me there is quite a bit of creosote build up and they clean the cap every 3 months. The system is a fireplace insert with glass doors and fan surrounded by a rock chimney. I do have various sizes of stove pipe that I could build a triple wall from. I will search for an original replacement for the next month or so before embarking on the fabrication. If in the meantime anyone comes across a pipe that would work, please let me know.

    be well
    B
  7. yogabill

    yogabill New Member

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    humpin iron,

    Could you expand on your answer about why air cooled chimney is not recommended for wood burning stoves? I am a handyman and not a chimney specialist and would like to be educated.

    thanks
    B
  8. jeff_t

    jeff_t Minister of Fire

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    From chimneysweeponline.com....

    Air-cooled metal chimneys, which are designed to vent manufactured zero clearance fireplaces, actively cool the smoke. While cooling the smoke is a good idea when venting the super-hot exhaust created by zero clearance fireplaces, which send most of the heat from the fire up the chimney, it is the worst possible method for venting the already-cool exhaust from today's super-efficient airtight stoves. For this reason, code authorities have outlawed the use of air-cooled chimneys to vent airtight wood stoves.
  9. Milton Findley

    Milton Findley Feeling the Heat

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    An insulated chimney liner makes an air cooled triple walled chimney into an air cooled triple walled chimney chase though. Blocking the air flow makes it into a triple walled metal chimney chase.
  10. DiscoInferno

    DiscoInferno Minister of Fire

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    That's a slightly overbroad statement. My BIS Ultima (EPA woodstove in fireplace form) has 3 approved chimneys, one of which is double-wall air-cooled. Both the stove and the chimney are made by Security, and are an approved combination; it's probably true that you can't use that air cooled chimney for a non-Security (or Lennox) stove.

    My Majestic WMC42 (a non-EPA fireplace) came with the aforementioned "type S" triple-wall air-cooled chimney, which is the rare AC chimney that is HT2100 rated. Majestic is a CFM company, and that chimney is also used on some of their EPA fireplaces.

    So there are specific cases where AC chimney is approved for specific EPA stoves, and the customer's current setup might be one of those. (Not clear if we're talking about a non-EPA fireplace, an insert installed in a non-EPA fireplace, or an EPA fireplace.) It's true that AC is more likely to have creosote buildup, although on my Ultima it amounts to a few cups of dry powder every 2 years.
  11. jeff_t

    jeff_t Minister of Fire

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    There's also the ever so slight possibility that this person is burning not-so-dry wood.
  12. 98dingo

    98dingo New Member

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    Agreed. I would suspect user error before a performance issue.
  13. yogabill

    yogabill New Member

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    I will get more information as to make and model of the installed unit shortly (next day or two). With all this input more ideas occur to me. Is there such a product as a protective insulative jacket to put around the exposed stove pipe coming out the roof? I will also attach photos shortly for a better idea of what is there. I still need to add height to the pipe and I do have a 36" section of 8" diameter ceramic insulated pipe. Maybe I am entering into the realm of fantasy but are there other solutions out there besides a full reinstall? These folks are low on bucks and have been dealing with blow back smoke when the wind kicks up for a while now. They do go through about 6 cords each winter which seems a bit much to me around here. No doubt they have insulation issues to deal with also that hopefully I can deal with within the budget.
  14. DiscoInferno

    DiscoInferno Minister of Fire

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    As a purely practical matter I don't know how you would connect insulated chimney to air-cooled chimney. The air-cooled is probably some sort of snap connector, and insulated usually has some sort of twist connect.

    There is insulation wrap for chimney liners, but I don't know if it would do much here. The design of air-cooled pipe generally allows outside air to circulate between the layers, and in a triple-wall type it doesn't seem like insulating the other layer is going to affect the temp inside the inner pipe much.
  15. humpin iron

    humpin iron Feeling the Heat

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    Disco- the units you cite are classified as fireplaces, not air tight wood stoves and yes I'm very familiar with the BIS, I installed one of the first 50 ever made. You CAN NOT mix air cooled and insulated chimney. They were tested and approved with those chims. Wood stoves are not approved with air cooled chims, in the 70's nobody knew better......that was 35 years ago.
    The proper way to "fix" this problem is to pull the entire chimney system and replace it with the proper insulated system. Big bucks but it is the proper way to do it.
    Yoga- not being disrespectful here, but you may be getting in over your head, I'm very sure your in over your liability ins. You can not modify that chim or add any parts other than the original mfg parts (exact replacement parts). If you do you will own ALL the liability for that chimney forever. Just to give you an idea, I met with my ins guy today, my liability for this kind of work costs my company $19,000 per year
  16. DiscoInferno

    DiscoInferno Minister of Fire

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    So are you saying it's basically a loophole that some EPA fireplaces are approved to use air-cooled chimneys? Because there's not really any substantive difference between EPA fireplaces and EPA woodstoves; the former are just woodstoves in a zero-clearance shell. I guess the lack of connector pipe on the fireplace makes air-cooled more practical, as there's usually a special adapter or fitting where the bottom of the chimney connects to the top of the fireplace.

    In any case I agree you can't mix air-cooled and insulated, practically or legally.
  17. pen

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

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    It's my understanding that the air cooled was used for the exact opposite reason that you'd use insulated pipe. Insulated pipe keeps flue temps warm while also offering reduced clearances. I think their concern with some of these fireplaces was that they'd send so much heat up the chimney that insulated pipe couldn't keep the temps down for clearances on the outside so their solution was to used air cooled chimney to keep clearances low.

    If that makes sense. :-S

    pen
  18. jeff_t

    jeff_t Minister of Fire

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    I think that's what Tom was saying.
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