Short Chimney

[Joe Bruno]

Hi. I have a woodstove (Hearthstone) that exhausts into a 6" SS liner that is installed inside an existing masonry flue. From the back of the stove exhaust to the top of the flue it's just over 12 feet. Unfortunately, that is not quite tall enough, so it lacks a powerful draft. It works okay, but not great.

I was thinking to add four feet of metal chimney pipe as that would bring it up to spec. and should make a big difference. I am wondering how to achieve this. Obviously, a metal pipe cannot be attached to the liner. I would have to attach a metal receiver to the top of the masonry chimney, and then to connect the new pipe to that receiver. I do not see any such devices/brackets/etc. on the websites of chimney pipe manufacturers to do this. If the attachment was strong enough it might not need any guy wires. But I could guy the four foot section to the bluestone chimney cap if necessary.

An additional consideration is that I would have to take it down to sweep the liner. So it has to be removable. Unfortunately, I cannot sweep this flue from the bottom up.

If anyone has a great idea please share. Thank you, Joe

 

[moresnow]

Post pics of your existing stove to liner connection as well as the current liner top termination.

Google chimney transition plate.

 

[bholler]

Hi. I have a woodstove (Hearthstone) that exhausts into a 6" SS liner that is installed inside an existing masonry flue. From the back of the stove exhaust to the top of the flue it's just over 12 feet. Unfortunately, that is not quite tall enough, so it lacks a powerful draft. It works okay, but not great.

I was thinking to add four feet of metal chimney pipe as that would bring it up to spec. and should make a big difference. I am wondering how to achieve this. Obviously, a metal pipe cannot be attached to the liner. I would have to attach a metal receiver to the top of the masonry chimney, and then to connect the new pipe to that receiver. I do not see any such devices/brackets/etc. on the websites of chimney pipe manufacturers to do this. If the attachment was strong enough it might not need any guy wires. But I could guy the four foot section to the bluestone chimney cap if necessary.

An additional consideration is that I would have to take it down to sweep the liner. So it has to be removable. Unfortunately, I cannot sweep this flue from the bottom up.

If anyone has a great idea please share. Thank you, Joe

I know ventis and Jeremiahs make transition/anchor plates

 

[begreen]

DuraVent offers this solution for transistioning to DuraTech chimney.



The transition plates are sold in different dimensions according to the chimney top size. The slip connector supports the liner with a band clamp.

 

[Joe Bruno]

Thank you all. "Transition Anchor Plate" and "Chimney Anchor Plate" are great suggestions. Now I know what it is called in the trade. The pic of one such plate that one of you posted here is similar to what I had drawn up and was considering having fabricated locally. It would be much better to get one from a maker of whatever pipe I use to extend the flue. All the kinks would have been worked out.

Moresnow asked for a pic of the chimney top. Raining now, and dark, but it is a single slab of bluestone, 30 x 46 x 2 inches. Two clay-tile liners rise through the bluestone and extend 4" above the plane of the stone; one liner is 10x10 for the boiler, and the other is 10 x14 for the fireplace. The 10x14 is the one that has been lined with a 6" SS flex liner. The 10x14 flue tile is capped with a flat plate that has a 6" dia. nipple in the middle to allow the liner to come up through it. Before the plate was installed the company who did the job packed the space around the SS flex liner with some sort of rockwool insulation. The nipple was slathered with silicone caulk before it was lowered into place over the flex liner (that closes the small space between the nipple and the liner). The nipple has an indentation near the top, this provides a precise place to fasten the SS band clamp that secures the rain cap and completes the installation.

It seems the kind of Anchor plate pictured here would mean I'd have to cut off the 4 inches of clay-tile flue liner that sticks up above the bluestone. With a grinder that should be no problem. I will Google these tomorrow and see what is available.

As for the connection at the stove. I used the rear exit option on the Hearthstone stove. Per the photos I am hoping to attach, a 6" SS nipple about 12" long attaches the back of the stove to the SS tee behind the pickled steel surround you will see in the photos. The tee attaches to the SS liner with the built-in clamps. On the bottom of the tee there is a 45 and a cap that I remove to collect the crumbs when cleaning the liner.

Thank you all again.

 

[begreen]

What's on the wall behind the stove and on the panelwith the knob on it?

 

[Joe Bruno]

There is nothing "on the wall" behind the stove. There is no wall there. That "pickled steel" surround behind the stove covers the original firebox--where the fireplace used to be. The 6" SS tee mentioned in my post above is in the old firebox, behind the steel. The panel with the knob is the access door; I remove it to access the cap at the bottom of the tee to vacuum up after cleaning the flue. Since you studied the photos carefully, you noticed something black behind the steel panel. To save you the trouble of asking, that black is a 1x1 square tube welded steel frame. It attaches to the masonry wall along the margins of the original firebox with concrete anchors. It provides a secure frame for the 1/8" pickled steel surround. The frame is tapped at intervals so the surround can be attached with machine screws. The hearth is 1/4" steel, treated with the same pickling process. Under that is the masonry base upon which the granite hearth used to lay.

I hope that's clear. I am still trying to figure out how to extend the flue an additional 4 feet up at the roof.

Correction: The hearth is 1/8" steel, as is the surround. The mantle, on the other hand, is 1/4" steel and is also pickled in the same manner, but it has a glossy finish instead of the satin or matt on the surround.

 

[begreen]

Thanks, I was wondering what created that unique look. It provides a nice contrast to that big rock.

 

[Joe Bruno]

Thanks, I was wondering what created that unique look. It provides a nice contrast to that big rock.

Thanks, I was wondering what created that unique look. It provides a nice contrast to that big rock.

Thanks. I was impressed with it myself. I had never done any ornamental rusting of a metal. The cool thing is you can wash it off and start over until you get the look you like. To fix it I used Penetrol. The finish has held up to the heat; it gets especially hot behind the stove as it's only about 4 inches away. BUT, being that it is hollow behind, the steel has a chance to dissipate the heat. What really has surprised me is how well the Penetrol finish is holding up on the hearth. After 2 years, no scratches or wearing out. On the mantle is used many coats to seal the rust better and to get a more washable finish (one can't really "wash" rusty metal unless it's under a finish).

 

[Joe Bruno]

Post pics of your existing stove to liner connection as well as the current liner top termination.

Google chimney transition plate.

I have replied to everyone below. Including more pics. Thanks

 

[Joe Bruno]

So, what I have determined is that I need a transition place, as you folks have pointed out.

I spoke with a chap at Rockford Chimney. They make such a plate. It comes with an 18x18 base and a Class A collar sized to your flex liner. The collar stands up 1.5 inches above the plate and one attaches the first piece of Class A pipe to the collar. On the bottom side it has a different collar with a SS strap clamp to attach the flex liner. This is a disadvantage for a retro fit, as my liner is installed and not easy to disconnect down below so I can pull it up and make the underside connection. (It's possible, but not easy). With a bit more engineering they could have made the liner connection on the top side. My other concern is that the 1.5" collar does not appear to be welded to the base plate. The lack of a weld is a strength issue and a water issue. I need to call them and be sure on this.

To make a base plate work, the clay-tile liner needs to be trimmed down to the level of the chimney top. The Rockford tech to whom I spoke said they recommend covering it in a 1/4 screed of mortar to prevent water seeping under. This concerns me as I do not see 1/4 inch of mortar lasting on top of an 18ga sheet of SS. Movement in the pipe above will cause the base plate to flex and the mortar to crack off. Any thoughts on this?

Tomorrow I will check on other brands to see how they solve these problems.

Thanks for your interest and support.