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Yet another liner question

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Adahn, Sep 17, 2012.

  1. Adahn

    Adahn Member

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    Our 1893 house was thoroughly renovated circa 2006 before we bought it. There is a centrally placed open fireplace with a masonry chimney with one 8" metal liner which runs up to the cap. A second metal pipe runs parallel from the gas boiler and water heater in the basement.
    What can I assume about this install regarding code for that time, specifically whether the liner is insulated or not?
    I've been using a smallish insert with a 6" to 8" adapter plate for the past few years but have been planning to upsize to freestanding and want to be safe on the chimney side of things.

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  2. webby3650

    webby3650 Master of Fire

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    It would be hard to tell if the liner is insulated. It would only be required if the clay liner (if it had one) was busted. If it has no clay, then it should be insulated. You might be able to pull the top plate to inspect. Be careful, the top plate and clamp might be holding the whole thing up.
  3. Adahn

    Adahn Member

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    Is it possible to run a preinsulated 6" liner up an existing 8" liner or does the 8" need to be removed?
  4. webby3650

    webby3650 Master of Fire

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    It's possible, but I wouldn't unless it was a rigid 8" liner.
  5. Grisu

    Grisu Minister of Fire

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    I have a hard time picturing this. Is the second pipe going through the fireplace or how can it use the same masonry flue? Or does the chimney have two independent flues?

    There are some stoves/inserts out there that use an 8"-flue. For those you would not need to change the liner if the current one is still in good shape. The question is if you need that much firepower as those are mostly larger units.
  6. Adahn

    Adahn Member

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    Grisu,
    Two flues from the looks of it. FWIW the exterior dimensions of the chimney in the attic are 27x27".
    An insert sized for 8" would be much too large both for the FP and the room, I think.

    I got a look at the space behind the block off plate keeping the 8" liner in place, as the liner has come loose from the plate. The metal liner itself isn't insulated, there's no fill around it in the chimney. I can't see the original chimney liner from the FP so can't assess its condition.
    I'm guessing it would be best to run an insulated 6" to be safe.
  7. Grisu

    Grisu Minister of Fire

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    That's similar to my setup although we don't use the downstairs fireplace to which the second flue is connected.
    That is certainly the safest and therefore preferred option. Do you already have an insert in mind? What kind of space do you want to heat?
  8. Adahn

    Adahn Member

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  9. bholler

    bholler Minister of Fire

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    This is not true. The liner needs to be insulated if there is not the required clearance from the exterior masonry of the chimney regardless of the condition of the clay liners. 1" is required for an external chimney ans 2" for an internal. And yes you can probably get an insulated 6" liner inside that 8" one but you could probably also easily pull out the 8" and sell it if it is in good shape.
  10. webby3650

    webby3650 Master of Fire

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    I know your real big on those clearances on masonry chimneys. But the fact is most don't meet these clearances and they never have. If every one had to meet this 2" rule or not be used, very few people would be burning. I am all for doing it correctly, but when a masonry chimney doesn't have this 2" clearance and the flue has 2' of solid stone around it, it's hard to sell a $2500 liner to someone with a solid chimney.
    I don't believe in fudging clearances on any class A, but sometimes clearances on a masonry structure are just not a big deal. IMHO
  11. bholler

    bholler Minister of Fire

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    I absloulty agree with you if there is 2' of masonry i would not worry about it either but the op asked if it need to be insulated to meet code and the answer is yes it does unless there is proper clearance on the outside. I rarly try to sell a liner to someone based on clearance to the exterior masonry if the existing liner is in good shape but if i am putting a liner in it will be insulated in order to meet code and be as safe as possible. By the way it is very rare to have 2' of masonry between the flue and the house on the sides maybe but not on the face. Yes sometimes the clearance on masonry isn't there that is why you should insulate.
  12. webby3650

    webby3650 Master of Fire

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    I always do!
  13. bholler

    bholler Minister of Fire

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    well good we are in agreement then. I didn't mean to argue with you at all i generally agree with you but your earlier post just was not true so i felt i had to correct it. I agree that there are plenty of instances where meeting that requirement isn't totally nessecary. But at least in our area most of the chimneys we see only have 4" or 6" of masonry and in those cases i feel that it is important to make sure everything is properly insulated because in that short distance there could potentially be enough heat transfer to cause a problem.
  14. Grisu

    Grisu Minister of Fire

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    Since the other thread has been closed now, I am posting my response again:

    One good reason to go with a freestanding stove over an insert will be the difficulty of finding a stock surround that fits your fireplace in case of an insert. Many may just stick out into the room on the left of the fireplace opening. The Woodstock Fireview is a great medium-sized catalytic stove from a company with excellent customer service. Are you planning on using it to heat the whole house? It may be a bit undersized for 1700 sqft in NY unless during that remodel the insulation was upgraded significantly. A catalytic stove has the advantage that even with a low burn rate it burns cleanly. It is therefore easier to go larger and then adjust the burn rate as needed compared with a secondary burn stove. When it gets really cold you then have the option to increase the heat output. Long story short, I would also take a look at the Progress Hybrid if you want to rely predominantly on wood heat. If you don't mind supplementing your heat a bit with your standard heating source when it gets really cold, a mid-size stove of about 2.3 cu ft in firebox size like the Fireview should be enough.

    Are you planning on removing the raised hearth? What is the height of the fireplace measured from the floor? There may also be other options for rear-vented stoves albeit non-catalytic ones e. g. from Jotul, Hearthstone and Quadrafire. For any stove you will need to check the side clearance to the wall on the right side. I also don't like how close the floor trim is to the fireplace. You may want to remove that, too, while doing some changes to your fireplace.

    With an insulated liner you will not get much heat from the chimney in the upper floors anymore. Does the warm air travel up the stairwell?

    If anyone else would like to chime in here is a picture of the fireplace: http://www.hearth.com/talk/threads/looking-to-upsize-insert.78201/#post-1000099
  15. bholler

    bholler Minister of Fire

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    Yeah it looks like there could be a few clearance issues there that is a weird but interesting setup.
  16. Adahn

    Adahn Member

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    Thanks for the replies; all input appreciated.

    Re: the liner: the 8" uninsulated liner was sufficient to meet code for a regular open FP whether or not the ceramic liner is intact, but a stove either needs an intact ceramic liner + uninsulated metal + 1" pipe-to-brick OR insulated pipe regardless of the condition of the ceramic, correct?

    Grisu,
    Hearth and side trim will be removed and replaced with near floor level tile if I go freestanding. Existing hearth is 4" high but not deep enough for a larger, non flush insert, so I'd have to cover the floor in front. I also don't know what is under that 1" stone slab. House was insulated reasonably well in '06 reno, so stove is for supplementary use and for power failures. Upsizing to a PH or similar size would disrupt traffic in the room.
  17. Grisu

    Grisu Minister of Fire

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    If you don't want to try to heat your home exclusively with wood the Fireview and any similar sized stove will be fine. I just wanted to make sure you are not disappointed when the furnace/boiler still has to run occasionally. Two caveats with the Fireview: The manual is a bit vague but according to this thread the hearth needs some r-value: http://www.hearth.com/talk/threads/need-some-help-with-fireview-hearth-requirements.111830/ I would contact Woodstock to see if using just tile will be sufficient. In addition, the corner clearance to the sidewall is 18" without heat shield which you may want to confirm that you have that. Should it turn out that the Fireview does not fit, I would take a look at the Quadrafire Explorer 2 (recent replacement of the Cumberland Gap). It has really close clearances and ember-protection only as a hearth requirement. It is slightly larger than the Fireview but not by much.
  18. Adahn

    Adahn Member

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    Regarding output, the doubling in firebox size and move to freestanding should fulfill our needs and expectations.
    For the hearth surface, tentative plan was to sawcut the floor to the sub floor and layer the durock/sheetmetal/tile sandwich as indicated in their instructions to keep it as close to current floor level and protect errant toes. Side clearance to wall works with a right side door if the baseboard is removed and the hearth extends that way.
    Yes it's an unusual layout, and not my design.
  19. bholler

    bholler Minister of Fire

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    No none of that is right the 8" bare liner does not meet code unless there is 1" of space between the masonry on the outside of the flue and any combustible materials regardless of the condition of the clay liner. And the same will go for a 6" that will go in there. It doesn't matter if it is an open fire place or a woodstove if it is a solid fuel burning appliance it needs 1" for an exterior chimney and 2" for internal ones. This does not apply to the fire box or smoke chamber there are different requirements in these locations. The only exception to this is that you can have combustible trim touching the corners of the chimney as long as there is 12" of masonry between that corner and the flue. And those clearances are not pipe to clay liner they are exterior of the chimney to combustibles.
  20. Adahn

    Adahn Member

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    Got it thanks. Is Insulflex still the go-to here? I've seen it mentioned in several threads.
  21. bholler

    bholler Minister of Fire

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    I personally have never heard of insulflex brand. There are allot of good pipe manufactures out there we like to use heavy wall flex pipe for wood stoves but it does cost allot more that the light wall stuff.
  22. Adahn

    Adahn Member

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    Working on estimates now.
    Any other opinions for Olympia Forever Flex vs. Magnaflex Insulflex vs Champion Easyflex or others?
    Edit: the Insulflex is listed as 7 3/8" OD, and might fit inside the existing 8" liner, assuming that's acceptable. The others are listed as 8" OD, and would require removing the current liner. All 3 seem to be zero clearance.

    Regarding changes need to the hearth: existing hearth is 16" deep, 1" granite slab over original 4" brick. I can add to/extend the existing masonry vs. completely remove it and rebuild at floor level (micore plus tile). Opinions ?
    Last edited: Jun 12, 2014
  23. Adahn

    Adahn Member

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    Update:
    Fireview sitting in crate. 4" tall brick/1.5" bluestone slab hearth over subfloor in progress. The old hearth had brick under that black granite slab and wood trim.

    Getting some big numbers for liner replacement. Existing liner is heavy flex wall and in good shape, described to me as probably being 'forever flex' and almost a shame to toss. Thoughts on pouring insulation between liner and flue? It might be hard to ensure 1" liner-masonry gap given the angles involved. One idea floated was to run a new 6" up the 8" and pour in between them. How about remove/wrap/reinstall the 8?
  24. bholler

    bholler Minister of Fire

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    forever flex is light wall not heavy And if it will fit you could pull it wrap it and put it back in i am sure you will not get 1" if you put the 6 inside the 8 but it could be done
  25. Adahn

    Adahn Member

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    Yes, I was mistaken on the 'forever flex' part....too many 'flex' brand names to keep straight, but the current 8" is a heavy liner, possibly 'superflex' which I believe is 316. One suggestion was to pour thermix/everguard/vermiculite around it and call it a day.

    edit: portion of chimney in attic that is accessible is 4" masonry.
    Last edited: Aug 6, 2014

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