Help with D-I-Y chimney liner?

[hc18flyer]

Before the heating season comes I will likely have to put a liner in my masonry chimney. It is the rectangle 8 x 12 " nominal tile liner. I think I am missing a joint between the tiles and some creosote is running down on the outside of the chimney, I think the damage is close to the attic/roof line. I have a newer woodstove with a 6" pipe connection. My chimney is 25' from basement floor to the top. I have excellent access, and flex or rigid liner should be very straightforward. I have been doing some leg work, but would appreciate any help you can offer? Hoping someone here has some experience to share? Thanks, Tom

[bakerjw]

Our chimney has a rigid liner in it which IMHO is the way to go. Clex pipes are corrugated IIRC and will likely cause less flow. We have to do the same thing to my mother in laws chimney too. A lot of cracked bricks and tuck pointing needed too.

[cwtebay]

If it's only a wood stove, I am betting that your.(creosote) leak is water coming in from your roofline. I would do a pretty thorough inspection of that before any liner. Putting a liner down a flue with a water leak will only help the water to damage further into your house.


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[hc18flyer]

cw- I full intend to clean and do a through inspection before proceeding,
Thanks, Tom

[ShooterAZ]

Once you get the creosote leak corrected and the chimney relined, I would recommend pouring vermiculite all around the liner. It insulates, and will improve your draw. Having a warmer insulated chimney will greatly reduce creosote build-up too. Sometimes you will have to run flex through the damper section, unless you cut it out with a torch. Stainless steel rigid is the best way to go for sure. I used to sell and install wood-burning fireplace inserts In the 1980's and 90's.

[hc18flyer]

Vermiculite as opposed to wrapping the liner with an insulated, foil backed batt? I manage a commercial greenhouse, so have access to perlite and vermiculite. I actually poured perlite between the clay tile liner and the concrete blocks when it was built 40 years ago.

[Freischütz]

If you need more help there are lots of helpful people at hearth.com

[ShooterAZ]

Vermiculite as opposed to wrapping the liner with an insulated, foil backed batt? I manage a commercial greenhouse, so have access to perlite and vermiculite. I actually poured perlite between the clay tile liner and the concrete blocks when it was built 40 years ago.

Yes, the vermiculite is easy to install, just pour it in and tamp a little as you go.

[Agent1187]

I've done two for woodstoves, and one for a kitchen vent. All using those flexible SS liners from Rockford that you can find on ebay.

Straightforward installs for sure. It helps to have two, even if just to yell from below to stop right there.

If you have or plan to use a modern high efficiency stove, getting one wrapped in insulation would be beneficial for reducing creosote and condensation inside the liner, though it's not absolutely necessary.

The biggest hurdle will be terminating a 6" pipe in an 8x10 hole since the chimney will basically hang off the cap termination. You'll need some kind of support for that big of span.

[higgins]

I've done two for woodstoves, and one for a kitchen vent. All using those flexible SS liners from Rockford that you can find on ebay.

Straightforward installs for sure. It helps to have two, even if just to yell from below to stop right there.

If you have or plan to use a modern high efficiency stove, getting one wrapped in insulation would be beneficial for reducing creosote and condensation inside the liner, though it's not absolutely necessary.

The biggest hurdle will be terminating a 6" pipe in an 8x10 hole since the chimney will basically hang off the cap termination. You'll need some kind of support for that big of span.

If you don't want to do it yourself, have a sheet metal shop fabricate a chimney cover with a hole in it for the metal pipe. That will keep water out of your chimney while supporting the end of the pipe.

I used flex through the damper and to get around an elbow to get to the standard pipe sections I used. That way the damper frame was supporting the weight of the pipe instead of the stove. I put the pipe together in 6" sections with stove cement in the joints and did the final assembly with cemented joints on the roof as I lowered it to the flex pipe. I lowered it with rope through loops of pipe strapping I installed at some of the joints when I put them together. Make large loops so you can snag them with a hook on a rope or extension pole in case you need to pull the chimney liner out of the masonry chimney in the future.

[Bmi48219]

Once you get the creosote leak corrected and the chimney relined, I would recommend pouring vermiculite all around the liner.

Remember vermiculite will absorb water. A flue cap sized for your existing clay flue liner is a good idea. If you’re missing a joint between liners you may be able to reach the joint and tuck it from above.

[hc18flyer]

Sunday I cleaned the chimney and inspected what I could. I did find a place on top where rain could get in and carry creosote to the outside concrete blocks. I cleaned and caulked that securely. I plan to rent a 'chimney inspection camera' from a reputable chimney source and check out the liner as best as I can. If that all looks good I will pour a new solid concrete cap over the existing soft brick and call it good. If I have a cracked tile, or more likely a mortar joint that has failed, I will have to put a liner in. Thanks for your help! Tom

[hc18flyer]

Remember vermiculite will absorb water. A flue cap sized for your existing clay flue liner is a good idea. If you’re missing a joint between liners you may be able to reach the joint and tuck it from above.

Bmi48219- From what I can see of the leak, it is in the top 5', which is soft brick and has some cracks. I may decide to tear the top brick off and continue the concrete block, or put brick and finish with a concrete cap? Tom

[ShooterAZ]

Remember vermiculite will absorb water. A flue cap sized for your existing clay flue liner is a good idea. If you’re missing a joint between liners you may be able to reach the joint and tuck it from above.

Yes, absolutely cap the chimney to prevent water entry! Sheet metal shop will make you a rectangular or square cover that your liner will come up through. Then put an appropriate chimney cap and storm collar on (usually comes with the kit).

[Buck Shot]

Once you get the creosote leak corrected and the chimney relined, I would recommend pouring vermiculite all around the liner. It insulates, and will improve your draw. Having a warmer insulated chimney will greatly reduce creosote build-up too...

I'm thinking of adding a rigid liner to the other stack in this old farmhouse, and I've been doing a bit of research on it, and while I agree you want to fill the void between liner and original masonry stack for the reasons you mention, if I'm not mistaken, they no longer "bless" vermiculite filler. I think now they want you to pour something that sets up solid almost like concrete.

As someone else in the thread mentioned, hearth.com has a lot of knowledgeable folks who can shed light on the current codes and customs on these things...personally, I would want to do everything "by the book" in case you ever need to claim a loss on insurance because Lord knows they always try to find an "out"...

Edited to Add: When I was doing my research, I found a really good white paper on chimney fires by the "Chimney Safety Institute of America" ... very worthwhile reading, as I learned a lot from it:

Chimney Fires: Causes, Effects & Evaluation
https://www.csia.org/uploads/9/0/7/3/90732795/chimney_fires_white_paper.pdf

Chimney fires are very bad news and can do some remarkably bad (and surprising) things due to the physics of what's happening inside the stack during a fire. For example (this is a direct lift from the paper above):

One of the more dramatic and potentially
dangerous effects of some chimney fires is back-
puffing of smoke and sometimes flames from the
appliance or venting system. This effect is caused
by a series of rhythmic explosions of fuel-rich
creosote gases in the confined area of the flue. As
the gases burn, they may consume the available
oxygen faster than it is supplied. When the
concentration of oxygen in the gases reaches the
lower limit of flammability, the flame is
extinguished, but plenty of heat remains in the
flue. Air will re-enter the flue and mix with the
gases which then ignite suddenly and explosively.
The result is immediate high pressure in the
chimney which cannot be fully relieved out the
top and smoke and flames may be driven through
any opening in the flue or appliance. As the
oxygen is again quickly depleted and flames are
extinguished, the pressure drops suddenly,
drawing in more air to initiate the next explosion.
This cycle may be repeated several times a
second.

If I recall right, the paper also talks about how a chimney fire can turn your stack into a volcano, shooting embers and burning blobs of creosote out the top, where they can land on your (asphalt shingle) roof and set it on fire...apparently when creosote catches fire, it expands to something like 12X its original volume, like expanding foam. Nasty stuff.

I now realize that the (2007) paper linked above is where I read about the vermiculite (again, this is a direct lift):

When they were first introduced,
many stainless liners were insulated with a loose
fill of vermiculite or similar material. This is no
longer allowed because of concern for settling and
sifting of the material into the flue. There are two
major types of insulation now in use: 1) a wrap
of foil-faced ceramic fiber blanket and 2) a
poured-in-place masonry fill. The blanket is
wrapped around the liner before insertion, covered
with an abrasion-resistant wrap, and lowered into
the chimney as a unit. The masonry fill is a damp
mixture of Portland cement and expanded mineral
such as vermiculite. It is poured into the chimney
around the liner and allowed to cure. Listed
stainless liners must provide a specified amount of
space around the liner to allow the proper
thickness of insulation.

Anyway, I can't recommend that paper enough. It was a real eye-opener for me. Good luck and be safe!

[hc18flyer]

I will read the white paper. As a volunteer Firefighter for 43 years, I have worked many chimney fires and house fire's caused by them. I clean my chimney before the heating season, and when I get a warm day in January, I do it again, because I am anal about it. It takes all of 15 minutes. My newer smaller, re-burnering stove runs much cleaner than my old, larger 'Earthstove' did. My inspectlon camera is on it's way, have 30 days before it has to go back.