Will this External Chimney Draft OK for a Woodstove? See Picture

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Mich-Man

New Member
Dec 5, 2005
9
Kalamazoo, Michigan
I'd like to install a wood stove for use with the EXTERNAL chimney in the picture below. Maybe I'm overs-ensitized to external chimneys from reading the views on this great site, but thought I'd ask if anyone has a similar chimney that works or doesn't, or if anyone has any comments. Today, this chimney is 20 ft tall, and not much taller than the roof peak. Probably needs to be taller. It is made of regular 16-inch square chimney block with a 9 1/2 inch square hole in each block. No flue tiles in it, so needs a liner. It was built for and used with an oil furnace which has been replaced with a gas furnace in another part of the house, so now this chimney is unused. The wood stove would be on the first floor and enter the chimney about 6 ft off the ground. I'd probably have it installed by the brick company that also sells the stove I want, and they would get the chimney to the right height, line it right, etc. They seem to know their stuff. Also, this place faces a lake and usually gets a pretty good breeze. So, I'm wondering, if a stove was installed to code and spec would the cooling effect of the external nature of the chimney still make for problems? Got one of these external guys? Does it work? Comments appreciated !
 

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Mich-Man said:
I'd like to install a wood stove for use with the EXTERNAL chimney in the picture below. Maybe I'm overs-ensitized to external chimneys from reading the views on this great site, but thought I'd ask if anyone has a similar chimney that works or doesn't, or if anyone has any comments. Today, this chimney is 20 ft tall, and not much taller than the roof peak. Probably needs to be taller. It is made of regular 16-inch square chimney block with a 9 1/2 inch square hole in each block. No flue tiles in it, so needs a liner. It was built for and used with an oil furnace which has been replaced with a gas furnace in another part of the house, so now this chimney is unused. The wood stove would be on the first floor and enter the chimney about 6 ft off the ground. I'd probably have it installed by the brick company that also sells the stove I want, and they would get the chimney to the right height, line it right, etc. They seem to know their stuff. Also, this place faces a lake and usually gets a pretty good breeze. So, I'm wondering, if a stove was installed to code and spec would the cooling effect of the external nature of the chimney still make for problems? Got one of these external guys? Does it work? Comments appreciated !

One thing you didn't mention is where you live. This can be of great importance!

BUT, an insulated chimney liner dropped down there should work fine!

This might be a good situation for using a ss liner and thermix, which is an insulation that you pour down around the liner.

Make certain you brush out the chimney as well as possible before installing any liner.
 
since you have the space an insulater liner would work the best. You will need to add at least 2 more ft.. 3' if wind might be a factor

What I would do is have the masons cut in a ash cleanout door right where the 90degree bend, you uses it to connect to the house or old original connector from the removed burner, At that point I would install a tee instead of the 90% elbow for the transition up. The tee would have a cap and can make for easy observation of your flue conditions and you will thank me when it comes time to clean it. You just made the cleanning job much easier
 
Well, hey, the Mich-Man lives in Mich(igan)! Lower Pennensula, SW area. It's about 20* F at the moment. It doesn't get much colder than -10*F around here. Thanks for the reply.
 
elkimmeg said:
since you have the space an insulater liner would work the best. You will need to add at least 2 more ft.. 3' if wind might be a factor

What I would do is have the masons cut in a ash cleanout door right where the 90degree bend, you uses it to connect to the house or old original connector from the removed burner, At that point I would install a tee instead of the 90% elbow for the transition up. The tee would have a cap and can make for easy observation of your flue conditions and you will thank me when it comes time to clean it. You just made the cleanning job much easier
elkimmeg, why does he need to go higher? As long as he meets the height and horizontal distance from nearest object (roof) isn't that ok?

And if he's installing an insert, why the 'T' and added masonry cleanout? Can't he just sweep his chimney into his insert, like I do?

Am I missing something?
 
I think I understand why the 2' increase, his chimney must end 2' above anything within 10 feet of the top of his chimney. Looks of things, his chimney is the same height as his roof, and the top of his roof is within 10 feet of his chimney. We'll see if I'm right about that part.
 
Yeah. Definitely, if the chimney doesn't meet the 10 ft clearance to whatever. I couldn't tell from the photo, but looking again, I think you are right. I guess elk sees enough of these to pretty much know at a glance.

But still, why the cleanout and 'T'?
 
You are thinking in terms of an insert a straight drop with enough room to use a 90 or bend the flex 90. He is trying to line matching up with an existing flue outlet. Mighty hard to make than 90 when it can not be gotten to from below inside a chimney chase. So he has two options opening up the inside blasting a hole to make room to work or cutting a hole outside to get at the 90 connection. At that point a tee makes sense as aim the clean out cap towards the cleanout door at that point he can clean up and vertically plus being able to observe the chimney condition or buildup. It's not required, But think about it a definite advantage
 
I really appreciate all these comments. A little more info is that the old oil furnace had a single wall steel flue that went straight up thru the ceiling into the upstairs, then rose a couple feet off the floor up there then turned 90 degrees to horizontal and went thru the wall and into the chimney. I don't know who built this and would be surprised if it was up to code. Anyway, it's gone now. I'd rather NOT route the wood stove flue that way, mostly to be able to occupy the upstairs area where the old flue pipe was. I'll likely (?) have to cement-patch the old hole in the chimney upstairs - at the moment it is patched loosely with fiberglass insulation and dry-walled over. So, I'll then need to make a new hole in the wall & chimney on the main floor for the wood stove. I'm thinking. Thanks for reading.
 
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