1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)
    Caluwe - Passion for Fire and Water ( Pellet and Wood Hydronic and Space Heating)

Clay lined masonry chimney vs Class A Insultated

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by senorFrog, Oct 30, 2006.

Thread Status:
Not open for further replies.
  1. senorFrog

    senorFrog New Member

    Joined:
    Aug 31, 2006
    Messages:
    285
    Topic says it all, all things being equal, which one is better?

    Helpful Sponsor Ads!





  2. Eric Johnson

    Eric Johnson Mod Emeritus

    Joined:
    Nov 18, 2005
    Messages:
    5,705
    Loc:
    Central NYS
    The SS liner is best for burning wood.
  3. elkimmeg

    elkimmeg Guest

    Interior Clay 8/8 liner is best. It has the mass to store heat which helps promote draft. Metal is thin walled and has no storage medium. It will heat up fast and cool down just as fast.
    Just the opposite for clay,it will take onger to establish a draft but also continue promoting it. In the interior burning 24/7, eventually the bricks around the flue absord heat as well,
    as it passes threw living space, that too transmits heat to the living space
    My vote Clay interior 8/8 flue is best for modern day wood stoves
  4. wg_bent

    wg_bent Minister of Fire

    Joined:
    Nov 19, 2005
    Messages:
    2,248
    Loc:
    Poughkeepsie, NY
    Clay 1, Class A 1.

    I'll keep track
  5. Eric Johnson

    Eric Johnson Mod Emeritus

    Joined:
    Nov 18, 2005
    Messages:
    5,705
    Loc:
    Central NYS
    Interesting analysis, elk.

    I've used both, and I prefer the stainless. Here's why:

    1.) smoother inner walls promote draft;
    2.) "instant hot" means quicker draft on startup;
    3.) much easier to clean;
    4.) no potential cracks or voids in the liner or masonry to worry about--ever;
    5.) contains a chimney fire better (IMO & I've had fires in both).

    If you have an insulated ss liner inside a masonry chimney, then I think you get most of the advantages you discussed, plus all of the ones I mentioned.

    But overall, I'd say the ease of cleaning (and thus the greater frequency of cleaning) trumps everything else.

    I should qualify all this by saying that I've never owned an EPA-compliant wood burning appliance--just pre-EPA wood stoves, boilers and furnaces. So keeping the chimney clean was an important consideration.
  6. elkimmeg

    elkimmeg Guest

  7. elkimmeg

    elkimmeg Guest

    There is not much to debate, this is a situational issue. Should one be lucky enough to have a spare clay 8/8 liner, the scales tip in favor of using that flue, cost and convience

    If that is not an option, then installation cost and ease, is in favor of the class A chimney. Each has a place and convience, Really who would go threw the expense off installing a class A,
    if they have a a spare separate 8/8 to use. Which one is best?
  8. MrGriz

    MrGriz New Member

    Joined:
    Oct 11, 2006
    Messages:
    1,022
    Loc:
    Waterford, WI
    Ok, now I'm confused...granted that doesn't take much...

    Do I actually need to run a full ss liner with my woodburning insert installation? I was under the impression that I did, and I even started to understand why...now along comes this thread and, when read, unravels the entire sweater.... :gulp:

    Is there a difference in applications, did I miss something, is this a stove vs. insert thing, six minutes to wapner...
  9. elkimmeg

    elkimmeg Guest

    this is using an 8/8 clay flue VS a 6" class A chimney most suited for free standing stove installationd Inserts are installed in flue sizes larger than 8/8 .
    Like 8/12 or 12/12 the cross-sectionar area is too large to promote proper draft so a flue liner is used to match the draft requirements of the flue collar
    Yes most inserts do not apply to this dicsussion
  10. berlin

    berlin New Member

    Joined:
    Mar 6, 2006
    Messages:
    299
    Loc:
    Western NY
    interior; clay/masonry. esp. for burning mostly coal as i do
  11. Eric Johnson

    Eric Johnson Mod Emeritus

    Joined:
    Nov 18, 2005
    Messages:
    5,705
    Loc:
    Central NYS
    Most properly installed SS liners allow you to clean from below--in the basement if it's an inside install. I've never seen a clay liner that could do that, although it's certainly not impossible. Cleaning from indoors is a lot easier than horsing around with ladders and heights.

    I think we got off track here in any event. What's the original question?

    If the question is: "What's the best chimney to build from scratch for a wood burning appliance?" I'd say SS.

    If the question is: "I have an existing clay tile-lined masonry chimney. Do I need to put in a SS liner?" Then the answer is: It depends on the condition of the clay liner. Sometimes they're damaged beyond repair. Or to put it another way, if they're damaged they usually aren't worth repairing.

    Elk, have you ever used a SS liner?
  12. Eric Johnson

    Eric Johnson Mod Emeritus

    Joined:
    Nov 18, 2005
    Messages:
    5,705
    Loc:
    Central NYS
    Bumpski.

    Anyone else want to weigh in on this?
  13. Rhone

    Rhone Minister of Fire

    Joined:
    Nov 21, 2005
    Messages:
    824
    For aethetics I like a clay liner, I'm not a big fan of stainless gleaming in the sunlight though an Extend-a-flue can solve that easy enough. For cleaning, I like stainless because it's so easy. Incase of a chimney fire, I'd rather have stainless because if a clay flue gets damaged repair is costly, ss you can purchase replacement pieces or replace the whole thing and be good as new. For draft, I prefer stainless because it establishes quicker and I don't have to babysit it as long to get my fire moving.

    I guess my vote is stainless.
  14. Eric Johnson

    Eric Johnson Mod Emeritus

    Joined:
    Nov 18, 2005
    Messages:
    5,705
    Loc:
    Central NYS
    I think elk's wrong about the cool-down. The interior surface of an insulated stainless steel chimney shouldn't cool down until the fire is out. I think it would still be hotter than a clay liner at virtually every point in the burning cycle, except possibly at the very end, at which point there's no creosote left to accumulate. And cleaning an SS liner is a lot easier than clay, any way you approach it.
  15. thechimneysweep

    thechimneysweep Minister of Fire

    Joined:
    Nov 19, 2005
    Messages:
    791
    Loc:
    Bellingham, WA
    Class A Insulated Stainless gets my vote. We find less creosote in stainless chimneys, probably due to the smooth surface, round shape, smaller surface area and higher insulating qualities (when Security Chimneys debuted their 2100 degree HT chimney years ago, they advertised that the 1" of ceramic blanket insulation used in their product provided the equivalent insulation of 21" of solid brick).

    Providing a smooth, properly sized pathway for the wood exhaust while keeping it hotter so it flows better and doesn't cool to the creosote condensation point should reduce creosote formation in the flue and the resulting chance of chimney fire. And if you were to have a chimney fire, the stainless Class A is more likely to survive it undamaged: in order to get an HT listing, the chimney must endure exposure to 2100 degrees for 1/2 hour, three times. I've seen a demonstration where a section of terra-cotta flue liner cracked like an eggshell after the insertion and ignition of one balled-up page of newspaper.
  16. elkimmeg

    elkimmeg Guest

    the class A chimney or lined larger clay installations are better Did you know that code exist in NFPA211 that corrigated chimneys should be increased in size by 20%
    Why to overcome the frictional losses caused by the corrugation. That is actually written code but rarely enforced. Corrigation is not considered a smooth surface

    there are 4 or more different animals being discussed here
    # 8/8 interior clay lined
    # a corrigated liner in a larger clay lined chimney
    # a free standing class A smooth surface chimney
    # and is it worth linning and interior 8/8 clay chimney

    an insulated interior class A winds hands down.

    However with proper planning, meaning ease and location of the cleanout, there can be real advantages no class A chimney can compete. This is a rare situation well planed and thought out in advance, where the 8/8 is planned for a wood stove day one. My situation is unique. The clay liner iand stove is set up to fully exploit the massive granite facing as heat storage behind and to the sides of the stove, in a central interior location. Floor to ceiling 12' wide of granite rocks absorbing the heat 24/7. My cleanout door in directly behind the flue inlet thimble, where I can open the ash door clean up or down. Ican clean connector pipe without removal. Ideal for the peridoic inspections of what is going on in my chimney.
    As for chimney fire protection the class a and ss liner are better. But one should never let their chimney get to that condition in the first place.
    The best protection is to make sure there is no potential problem. Burn dry wood and inspect it once a month. Clean it at the start of the heating season and at the mid point, A liner is required in clay lined chimneys in less than good condition.

    It is my contention, if one has a good conditioned interior 8/8 clay liner,, that not much is gained by linning it, that is really the only valid point of this arguement.

    The other point is if planned right there is nothing wrong with my clay setup. But as I said is unique to me. All bets are off in exterior chimney locations and larger than 8/8 clay liners.
    My home was planned to incorperate saving energy from day one. R 28 exterior walls built into a hill on the north facing side. Large glass areas facing south capturing passive solar gain
    huge granite central chimney location ( the mass to store heat) separate dedicated flues
Thread Status:
Not open for further replies.

Share This Page