Opinion needed on a tool to remove clay flue liner

baymeeMarch 23, 2007

I have decided to install a stainless flue liner in my old chimney, but have to remove the old clay liner first. I've seen a product which looks like a 4" square piece of steel, which works with a drill.

Has anybody used one of these and what was your experience?

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bus_driver

Is the removal required because of space requirements for the new liner? I can think of no other reason to remove the clay liner.

    Bookmark   March 23, 2007 at 7:55AM
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baymee

Yes. I want to put in a minimum 6 1/2 X 6 1/2 square liner with 1" of insulation around it. The current clay liner is 6 1/2 X 6 1/2".

I hoping that somebody has done this removal.

    Bookmark   March 23, 2007 at 11:08AM
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baymee

I meant to give the clay liner measurements as 6 1/2 X 6 1/2 inside opening; probably 8 x 8 outside measurement.

    Bookmark   March 23, 2007 at 11:10AM
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kframe19

The only time I ever removed a clay liner I did so with an iron digging bar. It was already pretty well shattered from a chimney fire, I was just finishing it off.

Is it a self-supporting liner, or is it grouted to the sides of the chimney, as well?

If self-supporting, a hammer and a digging bar will do a lot of the work for you.

If it's grouted in place... good luck.

    Bookmark   March 23, 2007 at 11:45AM
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blacknumber1

Dynamite.

    Bookmark   March 23, 2007 at 2:51PM
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baymee

It's self supporting, but I don't remember how much space there was around the tile, which wasn't grouted in place.

I see number1 has come out of the cold.

The tool is spun by a drill. It is a square 1/2" thick piece of hardened steel, 4 x 4" and it connects to lengths of steel rod. The company claims they work great, but I'd rather get an unbiased opinion.

I asked a chimney sweep today for his price to break out the tile and he quoted a price of $800 for the 20' chimney. The tools will cost me about $150.

The snow is melted off the roof, so I'll take a look at the chimney and order my tools.

    Bookmark   March 23, 2007 at 5:11PM
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blacknumber1

Possibly an electric chipping hammer, if you have enough room to work with it.

    Bookmark   March 23, 2007 at 6:19PM
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airsome

Risky. Vibration will wreck mortar joints.
Don't mess with the chimney. Go out the wall.

    Bookmark   March 23, 2007 at 10:12PM
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don21

I would install a 6 inch square or round stainless liner inside the existing clay liner - Hammering the clay out is really going to be detrimental to the health of your chimney, I fear

Don

    Bookmark   March 24, 2007 at 10:08AM
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baymee

The breech of the stove is 8". If I put 1/2" insulation wrap around a 5 1/2 X 5 1/2" liner (equivelent to about 6" round), it will fit inside the existing tile.

It's a 60K BTUH unit and the chimney draft is excellent, but I'm wondering about the 2" drop in size from a breech of 8" to a flue of 6" ???

In oil fired equipment, a 6" flue is acceptable to 120K and even higher; twice the wood boiler capacity.

    Bookmark   March 24, 2007 at 10:20AM
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baymee

I just realized I was wrong about the breech. It's 7" and if I reduced to the equivelent of 6" with the 1/2 Super Wrap for UL standard, I'd be OK. I think most stoves today are using a 6" flue.

    Bookmark   March 24, 2007 at 10:29AM
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blacknumber1

How straight is your chimney? How do you plan on getting the liner in?

    Bookmark   March 24, 2007 at 11:01AM
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baymee

It's very straight. Put in from the top, riveting each section as I go.

I took a drive to a stove store and all the current stoves in my BTU range use a 6" flue, so I guess I'll leave the liner in, unless I find out something different until Spring.

I still need the boiler for heat for another 6 - 8 weeks anyway.

    Bookmark   March 24, 2007 at 2:18PM
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blacknumber1

ahh, most old chinmeys I have encountered are less than perfectly plumb, the chimney in my current house makes quite a turn in the attic in order to exit at the peak of the roof. I think installing a liner would be very difficult.

    Bookmark   March 24, 2007 at 3:16PM
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baymee

You would use the flexible liner, which is very easy to get down the chimney.

    Bookmark   March 24, 2007 at 9:01PM
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fairyprincess

Baymee:

If you go with a smaller stainless liner inside your existing clay flue, you could always pour sand into the voids between the liner and flue.

With sand instead of cement, you won't have any problem removing the liner for future replacement if you should ever have to do so in the future.

The thermal mass of the sand will also moderate expansion and contraction of the liner, reduce condensation tendencies in the stainless, and help retain combustion products within the flue should the stainless develop any cracks or pinholes.

I agree with the others that trying to break out the flue with a vibration tool from the top would compromise the integrity of mortar joints in the block supporting the flue. Up here in Wisconsin, the guys I know that do flue replacement do it by cutting into the chimney block at all levels, replacing the flue and then putting new block into the cut out section from the base up.

Good luck!

Fairyprincess

    Bookmark   March 26, 2007 at 10:16AM
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baymee

I've been doing alot of research on this lately. The sand idea is a good idea.

The most modern stainless liners use a dense 1/2" wrap around them, made of mineral wool. This satisfies UL standards, even without sand or mortar.

I talked with our lab engineer this morning and he doesn't see any problem with keeping the existing clay flue and using the equivelent of a 6" flue in the chimney, even though the flue outlet on the boiler is 7".

The reasons being that a 6" flue can handle up to 180K BTUH in heat and my boiler is only 60K BTUH max and it's an interior chimney in good condition.

My real concern from the beginning was downsizing from a 7" flue outlet to a 6" stainless, insulated chimney flue. Almost every wood stove today is using a 6" flue. We also have large boilers out in the field that have downsized from the recommended 6" flue (180K BTUH) to a 5" insulated flue with no problems at all.

I determined yesterday that there is a 1/2" of air space all around my clay liner and it's not the type of chimney where you could cut out block and replace it.

I'm not ordering any materials yet and I'll keep my ears open for opinions for a few weeks.

    Bookmark   March 26, 2007 at 11:22AM
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mr_havac

baymee, I can't offer much advice here as far as if that tool will work for you but I think you're worried about creosote build up in your block chimney and want to go with SS instead. What temp do you run your stove at?

    Bookmark   March 26, 2007 at 8:02PM
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baymee

Stack temp varies. This morning it was up to 800 while the fire was stoking and then dropped off to 250. The temp varies alot. My buddy has been using his identical boiler since the '80s and he told me last night that I should open the damper in this warmer weather and let more heat go directly up the chimney. I haven't had time to experiment with that idea yet.

All I know is that I've burned for 30 years in one chimney and also for 20 of the 30 years in the other chimney and never had creosote, and never cleaned them.

But, since this boiler is so versitile, I want to do the right setup.

    Bookmark   March 26, 2007 at 10:05PM
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mr_havac

We burn wood in a woodstove which is obviously different then a boiler but either way if you let those flue temps get up there like that several times a day you really shouldn't have much of a creosote problem. I run our stove at close to a thousand for about 10 minutes twice a day and our chimney is pretty much all outside. When we brush it down every fall its pretty clean. The key is to stay on top of it before it has a change to build up and ignite.

    Bookmark   March 27, 2007 at 6:03PM
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