Tall chimney!

[Planeweird]

Hey All,

I have a 30-40' internal masonry chimney(haven't measured yet but the house is 3 stories and the chimney is at least 9 feet above roof penetration).

So, I'm thinking that's gonna create a LOT of draft. With that in mind, would I be better off going with a non-insulated stainless liner? Also, would a flex help disrupt the draft a little as apposed to a rigid one?

I'm in Cincinnati and the fireplace opening is relatively shallow. It's currently plumbed for gas but may have at one time been coal(I've no way of knowing), so I don't know yet what the existing flue size is.

 

[Planeweird]

Bump...Anyone?

 

[begreen]

Perhaps dropping down in size to a 5.5" pipe would help. What's the stove?

 

[pumiglk]

Not my specialty but I'm thinking that is a lot of space to cool off emission and build creosote. Maybe better to be insulated to keep emmission hot with an in-line damper to control flow.

 

[rfalk]

I have a 35' tall chimney with 6" pipe and have had no problem whatsoever, though it is a new install and I have only burned for a couple of weeks. I insulated (perlite beads in cavity around pipe). Draft is really good. I have a Lopi Declaration. bob

 

[branchburner]

I think finding out that flue size will be helpful.
Bob, how did the perlite go? I'm gonna try that in few days.

 

[Saw-dust]

I know smoe stove have a max stack heigth as well as an minimum.

I know during a Lopi Liberty install the max was 32 or 35 foot. The install was in a 2 storie cabin over looking a hollow and the stove was in the basement. At the max we just cleared the minimum roof requirement. I've not heard if they have tried out the stove yet to see how it works.

 

[rfalk]

Branchburner,

The perlite worked fine. Because it is pretty fine (most is about the size of rock salt) I was worried about the perlite sifting down between the blockoff plate and the pipe and end up on top and around my insert. Because I had to feed the pipe down from the top of the chimney, I made the opening in the blockoff plate 7" in diameter to accommodate the 6" pipe easily. Once I got the pipe hooked up to the stove, I then bought from my chimney store some of the fiberglass (?) gasket rope that was about 1" in diameter and stuffed it carefully between the pipe and the blockoff plate. I used high temp caulk to then glue it to the blockoff plate (but not the pipe). My theory was that this rope would allow the pipe to expand/contract both in diameter and for the pipe to move up and down within the chimney in expansion/contraction and still provide a good seal for the perlite. I then got on the top of the chimney and first shredded some mineral wood insulation and dropped down the chimney (figured that first layer would help plug the perlite. Then I poured about 5 bags of perlite to fill. I have only burned for a couple weeks, but done have more than a 1/4 teaspoon of very fine perlite that sifted through.

As you have said, too much draft may be a issue. I notice that my stove hisses some at startup when there is lots of flame. That might be a result of a good draft and a well insulated pipe. Once the fire settles down, its no problem. Our insert works great. I will post pictures once the custom ironwork is done on the front of the insert.

Bob