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metal vs masonry chimney

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by haydenwelder, Dec 29, 2007.

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  1. haydenwelder

    haydenwelder New Member

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    We are planning to build a new home and shop. Both will have free standing wood stoves. I am looking for information on chimneys, essentially masonry vs metal stove pipe. We will have room for interior chimney which I understand will help produce some additional heat. Our biggest concern is safety as this will be our main source of heat in the winter and central heat to be used only as a backup. Any recommendations?

    The house will be using a Jotul F 500 Oslo and the shop will have Quadra-Fire 5700.

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  2. webbie

    webbie Seasoned Moderator Staff Member

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    In general the metal chimneys will be superior to site-built masonry. The tiles commonly used in masonry chimney are not very durable when exposed to weight and temperature stresses...next thing you know, they crack and you need to line the chimney!

    If you really want to go masonry, you can probably do some research and checking around to find the right materials and mason.....or, have the chimney built and a poured (Like Ahrens) liner installed when it is new. There may be other masonry options, such as building the outside masonry and then using an insulated rigid stainless steel inner liner.
  3. stove man

    stove man New Member

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    well put.......fabricated chimneys are superior to masonry chimneys. smoke rises in a spiral and the round fabricated chimney will stay warmer. As far as brands go I would stay with the top brands. The big box stores have good deals but I always felt something is lacking for the big price gap.
  4. fraxinus

    fraxinus Feeling the Heat

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    No question that modern metal chimneys are very good and far cheaper than masonry. If it were me, however, (and I had the money), I'd opt for a masonry chimney with a poured in place liner. These liners become an integral part of the chimney and improve draft because of their interior spiral configuration. The thermal mass of such a chimney also contributes significant heat to the living space over a long period. This thermal mass plus the fact that it will be an interior chimney should reduce creosote build up as well. Finally, the appearance of masonry is limited only by your (or your mason's) imagination in design and materials. A metal chimney is a steel cylinder.
  5. Nicholas

    Nicholas Member

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    Why not the best of both words ?
    Make a masonry chimney "chase" (example: 4- 8" block laid in a square leaves a 8" center chase) Fill the block cores solid with concrete and 4-#4 rebar (do not fill the center chase)
    Wrap the block in your favorite stone or brick, drop a stainlees flue down the center, and even pour some vermiculite (sp) around the flue.
    The thimble detail would have to be worked out while laying up the chimney.
    This would give You the performace of a S.S. flue with the saftey of 12"-16" solid masonry around it.

    This leads to another question, If I did this I would want some heavy gauge SS flue.
    is there any 14-16 ga. S.S. single wall flue ??

    Nick
  6. JimWalshin845

    JimWalshin845 New Member

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    Vermiculite is not approved for any masonry flue/fireplace application. I think rock wool would be the better product!
  7. Nicholas

    Nicholas Member

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    Noted ! :)

  8. webbie

    webbie Seasoned Moderator Staff Member

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    http://www.isokern.net/pages/chim/dmsys.htm

    is one good idea for a masonry chimney - a very superior one!

    And, Jim, can you point to some sources about vermiculite not being approved?

    I know that vermiculite is used in slurry mixes that are poured around stainless liners.
    Here are some links which mention vermiculite in chimney lining:
    http://fireplaces.bobvila.com/Article/845.html
    http://www.fluesystems.com/liners/info/chimney_liner_installation.htm
    http://www.chimneydoctors.com/homeowners-guide-7.shtml
    http://www.eurotechchimney.com/heatapp.html

    I think the key is to use vermiculite or perlite, etc. in some way that it is listed or encapsulated. There was a scare because some vermiculite came from a mine that also had asbestos.
    http://www.eere.energy.gov/consumer/your_home/insulation_airsealing/index.cfm/mytopic=11610

    Perlite seems to be a more common loose fill insulation these days.
  9. JimWalshin845

    JimWalshin845 New Member

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    Encapsolated it is fine, as a slurry used as a liner. I was refering as being loose to fill the void that was suggested by the poster.

    The second reason this:
    An article published in the Salt Lake Tribune on December 3, 2006 reported that vermiculite and Zonolite (a brand of insulation made from vermiculite) had been found to contain asbestos, which had led to cancers such as those found in asbestos related cases. The article stated that there had been a "cover-up" by W.R. Grace Company and others regarding the health risks associated with vermiculite and that several sites in the Salt Lake Valley had been remediated by the EPA when they were shown to be contaminated with asbestos. W.R. Grace Company has vigorously denied these charges.

    Although not all vermiculite contains asbestos, some products were made with vermiculite that contained asbestos until the early 1990s. Vermiculite mines throughout the world are now regularly tested for it and are supposed to sell products that contain no asbestos. The former vermiculite mine in Libby, Montana did have asbestos — in fact, it was found to have developed underground with and to be co-mingled with significant amounts of asbestos.

    Pure vermiculite does not contain asbestos and is non-toxic, but it can become contaminated over long periods if there is a presence of a secondary mineral called diopside. After millions of years of weatherization, the biotite turns into vermiculite and the diopside turns into asbestos. This appears to have happened to the vermiculite deposit at the Libby, Montana mine, and numerous people were unknowingly exposed to the harmful dust of vermiculite that contained asbestos. Unfortunately, the mine had been operating since the 1920s, and environmental and industrial controls were virtually non-existent until the mine was purchased by the W.R. Grace Company in 1963. Yet, knowing the potential for human health risks, the mining company still continued to operate there until 1990. Consequently, many of the former miners and residents of Libby had been affected and continue to suffer health problems. Over 200 people in the town died from asbestos-related disease due to contamination from vermiculite mining from nearby Zonolite Mountain, where soil samples were found to be loaded with fibrous tremolite (known to be a very toxic form of asbestos), and countless others there who insulated their homes with Zonolite have succumbed to asbestos-related diseases, most of whom never were employed in environments where asbestos was an issue.[3]

    After a 1999 Seattle Post-Intelligencer story claimed that asbestos-related disease was common in the town, the EPA, in response to political pressure, made cleanup of the site a priority and called Libby the worst case of community-wide exposure to a toxic substance in U.S. history.[4][5] [6] The EPA has spent $120 million in Superfund money on cleanup.[7] In October 2006, W. R. Grace and Company tried to appeal the fines levied on them from the EPA, but the Supreme Court rejected the appeal.[8] The United States government is also pursuing criminal charges against several former executives and managers of the mine for allegedly disregarding and covering up health risks to employees.[9] They are also accused of obstructing the government's cleanup efforts and wire fraud. To date, according to the indictment, approximately 1,200 residents of the Libby area have been identified as suffering from some kind of asbestos-related abnormality.[10] The criminal proceedings are ongoing as of July 2007.[11]

    Since the 1920s, vermiculite had been extracted from the Libby deposit under the commercial name Zonolite. The Zonolite brand was acquired by the W.R. Grace Company in 1963. Mining operations on the Libby site stopped in 1990 in response to asbestos contamination. While in operation, the Libby mine may have produced 80% of the world's supply of vermiculite.[12] The United States government estimates that vermiculite was used in more than 35 million homes but does not recommend its removal. Nevertheless, homes or structures containing vermiculite or vermiculite insulation dating from before the mid 1990s, and especially those known to contain the "Zonolite" brand, may contain asbestos, and therefore may be a health concern.
  10. webbie

    webbie Seasoned Moderator Staff Member

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    Just trying to keep the facts straight. "not approved" is a far cry from there having been trace amount of asbestos in some vermiculite mined in one mine.

    It is a bad idea of use the stuff loose anyway, because of it's tendency to seep out through tiny cracks. I used it once in a masonry chimney (as suggested by a relining apparatus that I had purchased) and discovered it running out like water (or like fine sand) from a crack in the basement!

    Again, just trying to keep the facts straight for folks who search these threads in the future. That mine is long closed and any vermiculite that is purchased today is very unlikely to be tainted. It appears to be used in a number of products, such as "boards" and mixed with portland cement.

    Maybe a better way of saying it is that folks should use a product which is specifically listed, tested or suggested (by a reputable sources like the Masonry Institute, Brick Institute, etc.) for insulation in a masonry chimney setup.

    Personally, I would go for the Isokern as above! That is masonry done right!
  11. JimWalshin845

    JimWalshin845 New Member

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    It is also an absorbant material when in loose form, so it will retain moisture next to your flue pipe. I don't think anyone would want this situation, do you?

    It has great insulation and fusion properties, makes a great slurry for many different applications, but I would not want it in my home in loose form.

    I worked in the real estate business and it is incredible how many homes are rejected by a buyer because there were signs of asbestos, even after it was remedied. This is going to happen with vermiculite too.
  12. Nicholas

    Nicholas Member

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    Guy's
    To clear it up, I was using "pour" as in pouring concrete, not loose fill. sorry to have not stated.
    I think this has gotten off topic, Vermiculite is a safe product and is used in home construction
    There may have been a bad batch, just as there are recalls on stoves, does not meen any house with a stove is a death trap.

    So lets assume we are pouring in a Insulating slurry around a S.S. liner, in a masonry chimney -

    1) is this the ultimate wood burners chimney as far a performance and saftey ?
    2) Is 8" S.S. available in heavy gauge ??

    Thanks,
    Nick
  13. webbie

    webbie Seasoned Moderator Staff Member

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    24 gauge or possibly 22 ga is the heaviest I know of (try Elmers Pipe). That is as thick, and sometimes thicker than what is used in insulated chimneys.

    Whether it is the ultimate chimney is another story. I guess if one used the best possible grade of stainless it could be up there. But there is also the option of that Isokern volcanic stuff and the poured in place liners. All have their up and down sides.

    Example: the thermix is for pouring around a flex liner (in general), which can expand and contract easier than rigid pipe. So will having rigid pipe make it harder for the inner liner to expand and contract separately than the slurry mix? I can't say.

    In general, I would say that a complete engineered system would in most cases outperform something that put together from scratch. Extra thickness of stainless can do more harm than good, due to inability to make make up for thermal expansion, etc.

    How about an insulated and armored rigid liner inside a masonry structure? That would seem able to take the max in expansion, etc.
  14. Nicholas

    Nicholas Member

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    Lost me :)
    Describe an "Insulated and rigid liner"
    Sounds like what I was thinking about - a "rigid" S.S. liner or flue, "insulated" in a slury mix, inside a masonry structure.

    I DO SEE what You are talking about with an "unproven" system - if there is no expansion joint between the S.S. flue and the slury/masonry, the whole thing could crack with the warm up.

    Is there a system allready available ? (S.S. insulated flue in masonry chimney), not looking for retro fit, this will be new construction.

    Nick
  15. webbie

    webbie Seasoned Moderator Staff Member

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    Companies like Heat-Fab sell a insulation for their pipe, with a armor on the outside so the insulation stays in good shape. I would assume this can be surrounded by the typical 4" of masonry. Other companies sell insulation which often has a mesh armor available with it - this is needed if the insulation is to be relied upon to stay in decent shape inside an unlined masonry flue. See the screen shot enclosed - this is Heat Fab and notice the paragraph mentioning the Saf T Wrap.

    I suspect that Duraliner is somewhat similar in scope and use.
    http://www.duravent.com/?page=4a.php

    Heat Fab is thicker......

    Attached Files:

  16. webbie

    webbie Seasoned Moderator Staff Member

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    So, in effect, Heat-Fab has the exact system you are looking for. It can be used in new construction (as a LINER) or in existing construction (as a RELINER)
  17. shortlid

    shortlid Member

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    I am guessing this will apply to my question on adding a chimney on a newer home that is already built. I could put a metal stud framed chimney with three flues going from the basement to the above roof line of a two story cape. Could I just use regular foil faced insulation inside the framed structure. I could stucco it, I was thinking about using a sawzall to take the exterior plywood, and insulation out from between the house framing and the flue housing. I would do this to help the house warm the flue and the flue in turn warm the house.
  18. webbie

    webbie Seasoned Moderator Staff Member

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    Not sure what you are proposing, but it does not sound kosher at first glance. Maybe you should start a separate thread for this......
  19. begreen

    begreen Mooderator Staff Member

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  20. woodconvert

    woodconvert Minister of Fire

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    "How about an insulated and armored rigid liner inside a masonry structure?"

    As someone who uses an exterior masonry chimney/clay liner....go with the double/tripple wall stuff. It's not even a debate. If you still want a masonry chimney it's all good, you can do whatever you want to do but go with an insulated liner. As for performance though, the clay liner masonry chimney is "fine" when you burn 24/7, it's cold out and you can keep the chimney hot all the time. All other times like spring and fall they almost stink. If I had to do it over again.....learning the hard way SUCKS. :mad:
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