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I have an old home with a masonry (stone) chimney and terra cotta flue liner for the fireplace. I need to have it relined because there’s a leak somewhere between the first and second floors of the house (you can smell smoke in the bedroom the flue passes by).
A contractor who has cleaned my flue previously and installed a stainless steel flue for my heater (it also runs up the chimney) recommended a process that relines with a thin layer of cement over the terra cotta by using a spinning orb that passes up and down the flue several times applying a very thin layer of the cement each time. He said this is better than using a stainless steel liner over the terra cotta because it will better maintain the dimensions of the flue which are critical to the draw. This approach seems expensive ($1900) and it only has a 10-year warranty. A stainless steel liner was estimated at about the same price but would have a 25-year warranty.
Any thoughts?
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Tom,
I am not a contractor, but a property owner who has had 4 fireplace flues relined in the past 5 years (3 in Chicago, 1 in Seattle). This area has been the most problematic of any renovation work I have undertaken. Here are some thoughts:
First, there are a very limited number of contractors who seem to really understand fireplaces (even though they are "certified chimney sweeps", or whatever). On top of that, everybody is pushing their own system of relining. And the liners are expensive. I talked to 7 chimney sweeps/contractors in Seattle before I found one that had something of a clue, and the project still went badly. And that fireplace still smokes.
My opinion is that the stainless steel liners are the best, because if the building settles a little, the stainless will give, while masonry will crack. That may in fact be the reason yours is leaking. There really should be no other reason why a terra cotta flue should leak. (Does the terra cotta run the entire length of the flue? Sometimes the top portion of the chimney was rebuilt, and the terra cotta was just put in the new portion).
A qualified chimney contractor should also be able to run a video camera down the flue to see what/where the problem is, especially if it's a smooth terra cotta surface. My feeling is that really understanding the problem will lead to a better solution.
Your contractor is right, the dimensions are important, but the ratios can be checked, so you should know if stainless is a feasible option or not, based on published information.
In Chicago I did stainless liners (Ventinox), and that worked okay. Only one of the fireplaces smoked until we added a 2 inch smoke guard. However this flue ran from the first floor to the top of a 3 story apartment building, with some kind of bottleneck about halfway up, that prevented the ideal sized lining from being used. In Seattle, on a 1.5 story house, all the contractors claimed stainless wouldn't work in a fireplace(none could give me a reason), and I ended up going with a ceramic, cast in place liner from Ahrens. That fireplace still smokes, although it's a complex problem that was made worse by adding the liner. I think I've almost got a solution figured out, no help from the contractor.
My suggestion is to be very careful, and get the contractor to agree in writing that the fireplace will not smoke when he is done with the work. Then test it to be sure, and don't pay him unless it works completely.
The best information I have found on the whole mysterious area of chimneys is a self-published manual by a full time chimney consultant from Canada. He apparently goes around and figures out how to make them work, when nobody else can. I can try to find the book at home if you want, and give you the info. Also feel free to email me.
Good Luck!
Dan
*Tom,The problem with coating the inside of the flue liner with cement will be bad adhesion because over the years the terra-cotta will have absorbed oil and grease from the smoke. Far better to line the flue with as large a liner as possible.The source of the smoke may not be a broken flue -- it is good practice to corbel a flue over at least it's width and often the mason does not bother to put flue-liner bends at the corbel, just rough renders the brickwork. Later the render breaks away and smoke penetrates the stack.
*Thanks, Dan, Ian.Dan - you're right, there seems to be a lot more art htan science among the chimney specialists I've spoken to.Ian - I agree with your assertion that there may be a film that prevents good adhesion of a cement material. Maybe I can find some way to check out the part of the flue that's a problem. It has to be between a bend just above the fireplace and before the floor above because I can smell it most near the 2nd floor bedroom near the wall the flue passes by.
*If the corbel is just above the fireplace, then you may be able to check it out with a flashlight and a mirror. Have a look at the bottom of the flue liner, maybe some of the render has broken away and the smoke is getting between liner and stack. The space between liner and stack should have been filled solid with a sand/lime mixture but they cut corners even in the 'good old days'!Dan,Does the fire smoke all the time or only when there's a wind blowing?If it's only when the wind is blowing then it may be a down-draught caused by over-hanging trees or the top of the chimney lower than the ridge, etc. A down-draught can usually be cured by a cowl on the top of the chimney.If it smokes all the time, the fireplace throat may be too wide. Check this by blanking off the top, say, 4" of the fireplace opening with a piece of ply, or strip of carpet, etc., while the fire is alight and see if it draws better.
*Ian,It's definitely not a downdraft from wind, and I have already added a 4" smoke guard above the fireplace opening, which makes it somewhat tolerable. I am almost certain the problem is caused by the fact that the previous owner of the house hired a chimney guy to rebuild the firebrick inside the fireplace just before he sold the house to me. This tradesman completely changed the inside shape, running the insides of the fireplace almost straight up,without the usual inward taper to the flue. Furthermore, they removed the original damper system, and put a damper up on the chimney cap, controlled by a cable running down the flue to the inside of the fireplace. (Apparently this type of damper system is common here in Seattle, but I never heard of such a thing before I moved here).What this means is that when you stick your head in and look above the fireplace, there is a huge open area, with the relatively small flue opening above that. (There is nothing up there like a throat or a smoke shelf). What seems to happen is that because of this large area, some of the smoke cools and drops down before it can get sucked out, sometimes spilling back into the house. Pushing the wood all the way to the back of the fireplace helps. The easiest thing I can think of to try, when I get time, is to bend some metal and bolt it in above the fireplace and below the flue to narrow down the opening and therefore increase draft in this area.I'd rather have something professionally installed, like a proper terra cotta throat and damper, but as I said, I've gone through 7 chimney "professionals" here in Seattle, and none seem to have a clue, although they have proposed a number of strange ideas, which will cost large amounts of money to implement, with no guarantees.All advice is welcome.-Dan
*If you reduce the flue from 6" to 5" your fireplace capacity to draw (in pounds of smoke per unit time)is reduced by 40%, 8" to 5" reduces it by 70%!For my house I would make a choice between 2 evils:1: StainlessS flue and add glass doors to control draft. Plus- straightforward and relatively inexpensiveMinus - (glass doors are NOT self cleaning, and WILL break after a few years of thermal cycles of weekly wood fires)2: Tear the existing chimney down and rebuild from ground up with poured slipformed and lined concrete chimney - any outside you want.Plus - best there isMinus (or plus, depending on you) -- Become a compleat DIY, Read lots of books on box dimensions, get your hands dirty, and spend a few or many weekends learning on the job and the out of pocket price is less than the liner hired out.
*Dan,You are quite right -- the fire will always smoke with the set-up you describe. The position of the damper certainly seems odd to me, normally it is set in the bottom of the flue-liner but I suppose it must work if they commonly do it like that.You said the firebrick was re-done -- does that mean you could rip it out and replace it?Your metal sheet idea will work, but be a bit tricky to fix and you'll have to watch that soot can't lodge on it.Good luckIan
*Tom,How badly do you need to keep this a wood burner? Is gas availble?I just redid my fireplace with a gas insert. Has nice glass doors, solid brass trim, a thermally sensed fan, remote control (the wife loves that), and it's own flue liner. Looks great and solved my problem.
*There is an old method, using a weighted feed bag with a rope on both ends (in case it gets stuck) that you use to pack some furnace cement or fireclay mix into any gaps in the flue by working the bag up. This is messy and slow but you can do it yourself, don't need to pay anyone $1900.If you want more information, I can give it here or email me.Good luck,MD
*Please post the details. I (if nobody else) am interested.Mike
*It is a traditional method of re-parging a flue. A sack, usually filled with hay, is secured to a rope that has been dropped down the flue from the top. Another rope is tied to the bottom of the sack. The sack is pulled up into the start of the flue and several buckets full of a sand/cement slurry are poured down the flue as the sack is slowly pulled upwards. The problem is that any existing gaps are likely to be filled with soot and other greasy deposits which makes for bad adhesion of the slurry to the walls of the flue and after some time the coating cracks and falls off.
*Ian's got the basic concept down. I can't say how long the patch would last, but it's definitely the quicker/cheaper fix.MD
*Hi Pete,I just got back to this thread after several days away. The reason I'm stickin' with wood is because I use the fireplace for ambience first, warmth second. One note - it is entirely masonry by construction. Stone (real!) chimney with two terracotta flues, one for the heater and the other for my fireplace. Besides, I love the smell of buring wood (as long as it's not the frame of my house).-Tom
*I guess I could try to looking up the flue when the weather's a little warmer (it be chilly in Philly!). As I recall the flue takes a very unfriendly bend that would probably make it difficult to service from below. We'll just have to see...
*Tom Maybe the flue is not leaking at all. A tall chimney is like a siphon, if there was hot air going up the stack, it will suck in air, not blow it out. On a water heater, it has a draft diverter, and it draws air IN!
*TomFor your money have the terra cotta tiles removed and an appropriately sized stainless steel liner installed.To insure performance in the liner system make sure that it is insulated. To improve the smoke chamber have it paged with ChamberTech 2000, a refractory product. With your fire remember that the burning temperature of the fire itself influences the smoke temperature i.e.rate of rise as well as the volume of expansion of the smoke and air that must exit the chimney. Build hot fires in a safe fireplace, have it cleaned regularly and enjoy.
*TomFor your money have the terra cotta tiles removed and an appropriatly sized ss liner installed.To insure performance in the liner system make sure that it is insulated. To improve the smoke chamber have it parged with ChamberTech 2000, a refractory product. With your fire remember that the burning temperture of the fire itself influences the smoke temperture i.e.rate of rise as well as the volume of expansion of the smoke and air that must exit the chimney. Build hot fires in a safe fireplace, have it cleaned regularly and enjoy.
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I have an old home with a masonry (stone) chimney and terra cotta flue liner for the fireplace. I need to have it relined because there's a leak somewhere between the first and second floors of the house (you can smell smoke in the bedroom the flue passes by).
A contractor who has cleaned my flue previously and installed a stainless steel flue for my heater (it also runs up the chimney) recommended a process that relines with a thin layer of cement over the terra cotta by using a spinning orb that passes up and down the flue several times applying a very thin layer of the cement each time. He said this is better than using a stainless steel liner over the terra cotta because it will better maintain the dimensions of the flue which are critical to the draw. This approach seems expensive ($1900) and it only has a 10-year warranty. A stainless steel liner was estimated at about the same price but would have a 25-year warranty.
Any thoughts?