8" Double Wall to 10" Chimney

[Kwehme09]

My local hearth store has been hopelessly unhelpful on this one.

Pictured below is where my chimney enters above my hearth. The interior of the opening is 9 7/8". I have 8" double-wall pipe to run from the top of my stove, straight to the chimney. How to go adapt from the 8" double-wall to the 10" chimney? I can't find a manufacturer name anywhere on the chimney, even on the outside.

 

[pen]

What kind of appliance was here before? Are you sure this is class A chimney?

pen

 

[Kwehme09]

There used to be an older Scandia woodstove connected to it that looked like it had been run there for years (I just bought the house). There is no markings on the chimney, inside or out, so I can't be positive it is class A. However, I can tell it is insulated, 2" thick all around.

 

[pen]

Did the old install just have a piece of single wall pipe shoved into that?

9 7/8 is a huge chimney.

Do you need double wall pipe here for clearance to that wood paneling?

If it's far enough away (18 inches) as per the specs on your stove, then you could possibly use something like this http://www.ventingpipe.com/duravent-2067-8-10-single-wall-stovepipe-increaser/p1762890

Otherwise, I don't think I've ever seen double wall this big.

I think I'd get a sweep in here to check things out and make sure it can be safely used before you go too far.

pen

 

[northernontario]

Do you still have the old stove? You say it's a 10" (9 7/8") ID... did the old stove have a 10" connection? The first missing piece of the puzzle is the connection from the insulated pipe to regular black pipe... Do you still have the old pipe?

If you've got the connection to switch to black pipe, then you should be able to get an 8" to 10" transition in black pipe. Worst case, if the proper connection/clamp piece is missing to hoop up to the insulated pipe, you should be able to slide a 10" pipe (or your 8-10 transition) over the inner lip of the insulated pipe, and screw through to secure them together. Just make sure the overlap is in the proper direction (creosote dripping).

Does that make sense?

 

[Kwehme09]

I think it makes sense...

The old connection was an 8" single-wall pipe stuck into the opening pictured, accept there was a custom (retro/homemade) ring that covered the difference. This piece was rusted and in far worse shape than any of the other components. It crumbled away when taking out the old stove and pipe. I need double-wall pipe because the clearances are tight (18" almost exactly). I'd consider going single-wall at this point, however, the double wall is purchased and likely isn't returnable without significant restocking fees etc.

So yea, young guy, first-time homebuyer, tight budget, getting really frustrated and need to get this hooked up to appease my homeowners insurance. Ugh.

 

[Kwehme09]

Does anyone think this piece would work? (Warning, it is a PDF so it will take a minute to open).

http://www.duravent.com/docs/news/dvl_chimney_adapter_w_trim_web.pdf

The Trim piece would more than cover the 9 7/8 opening I have, and the 8" portion (athough not pictured) would stub up into my chimney a little. Too risky?

 

[pen]

I personally don't like the idea of an 8in pipe floating around inside a 10 inch chimney.

pen

 

[Kwehme09]

Well, it wouldn't float around up there. I wouldn't plan on running the 8" up through it, just into the bottom of it with that trim piece.

Just an idea?

 

[pen]

What about a 2000 degree piece of burning creosote that falls down the chimney and goes in the space between the 8 in and 10 in pipe? Whatever goes there needs to be able to withstand whatever could potentially take place in that chimney.

Do what you like, but I wouldn't be very comfortable with it. Did you look at the 10 to 8 inch adapter I posted a link to earlier? I know you are stuck on that double wall pipe but I think it's going to make things difficult for you.

pen

 

[summit]

sounds like a new chimney is in order... If it had a scandia on it, it's gotta be old, and probably not up to code.

 

[pen]

sounds like a new chimney is in order... If it had a scandia on it, it's gotta be old, and probably not up to code.

Agreed. At the very least I do hope he has a sweep come check it out.

pen

 

[Kwehme09]

I hear you. I am basically talking it out.

I think the piece you posted will probably be the way to go. I will probably adapt it, cutting down it's length a lot so I don't run as much single wall the whole way. Hopefully my double wall with fit into my doublewall, somehow.

Thank you for the advice. Wasn't meaning to question you so much.

Cheers.

 

[pen]

Hope it works out for you. Safety is the main thing here. Wood heat as a lot of benefits so long as the house and those in it are well protected!

If you do need to use single wall for an area then a heat shield may be used (attached to the combustible surface with a one inch air space behind it) to reduce clearances.

pen

 

[mhrischuk]

I am curious what caused all of the rust on that old home made transition piece. You really need to find out exactly what you have for a chimney before doing anything. Who knows what's corroded up there. See if you can gain access to the chimney along the way. Are there any manufacturer's labels or markings? Can you take more pictures ..... show us what it looks like exiting the roof too?

 

[begreen]

I hear you. I am basically talking it out.

I think the piece you posted will probably be the way to go. I will probably adapt it, cutting down it's length a lot so I don't run as much single wall the whole way. Hopefully my double wall with fit into my doublewall, somehow.

Thank you for the advice. Wasn't meaning to question you so much.

Cheers.

You'll need to determine several things before proceeding. Can you get a professional CSIA sweep to come out and inspect this installation? A good sweep will be looking for:

pipe type, clearances to combustibles, pipe condition, code compliance (10-3-2 rule, firestop, etc.), any signs of stress or chimney fire, etc.

That said, even if it passes muster, I'd be reluctant to use it if this is a short flue and you are going to connect an EPA 6" flue outlet stove to it. The 10" pipe will have about 3x the cross-sectional area and will probably draft poorly in this case, especially if this is a one story chimney.

Also, it looks like there is a lot of woodwork nearby so be sure to meet or exceed clearances for the connector pipe and the stove. Do you have a make and model already picked out?

 

[Kwehme09]

I can site up the chimney easily and it appeared relatively clean and sound. I can also inspect it from the outside, and it looks okay. My builder inspector and homeowners insurance company inspected it and neither had an issue. The rust is from the old retrofitted piece that fit the 8" single wall into the chimney. I doubt it was galvanized or stainless and the rust markings are from that, not from the pieces that are pictured.

However, I am probably going to break down. . I'm sufficiently convinced that fighting a connection to this 10" beast of a chimney would be silly. It will be a fight, and in the end, will may likely not work that well. AND, the existing chimney is old and may not be safe.

I am having my local hearth store (who I have no been thrilled with) come out and spec me a new 6" chimney. I am connectiong it to a VC Intrepid II 1303 that has its own set of minor problems you can help me with here: https://www.hearth.com/econtent/index.php/forums/viewthread/78579/ (please)

The stove aside, let's talk new Chimney. It is a single story installation. Straight up. Either through the box pictured in the photo, or I'll rip the box out and install it through the sloped ceiling. The ceiling is the roof. Uninsulated. Corrugated metal roofing. Should I have the hearth store install it or get the parts and do it myself?

A little on my background. I am an very experienced carpenter. 10-plus years frame to finish. I am a maintenance supervisor for a large lodge in the white mountains, 6 buildings, GARN 3200 wood-fired boiler, etc. I have a shop. All the tools I'll need. I just haven't done a chimney like this before. I can do a lot of things on my own, but when it comes to some things, don't mind deferring to a specialist. I like things done right, whether done by me or someone else. So... do it myself, or no?

Thank you Pen and Company for the advice so far.