Wall Thimble

[joedirt16]

Long story short, my family moved into an old house this summer. It has a heat pump/forced air system, but we want to install a wood stove, as the back portion of the house is unheated. (Must have been an addition some time ago.

This SST exterior stove pipe was existing. If you look close, I believe the brackets are mounted incorrectly, and the pipe exiting the house angles down.

The other problem I think I have is this....

Ehhhh, I guess the guy that lived there before us wanted some insurance money for the house fire he was trying to start? (Side note, there is a stud running a few inches, to the left of the pipe.)

I want it right, obviously. Besides correcting the pipe/bracket, is it as "simple" as installing a thimble? I have seen numerous posts similar to this, but going into a masonry chimney.

The other catch is the wall is deep. Off the top of my head, at least a good 16" deep.

Advice? Local place wanted to charge over $2500 to fix. Seemed a bit high when I think I can do it myself.

 

[VirginiaIron]

You would have to find out who manufactured the piping system and follow their installation instructions. Here is an example from a DuraVent system. (broken link removed to http://www.duravent.com/docs/product/L119_W.pdf)

At first glance, the T is not fitted perpendicular to the rising pipe. Maybe the tree support was not high enough to support the tree, maybe the pipe slid down due to improper supports. Check the decals and find the correct installation document even if you have a professional contractor make the repairs/adjustments for you.

 

[joedirt16]

You would have to find out who manufactured the piping system and follow their installation instructions. Here is an example from a DuraVent system. (broken link removed to http://www.duravent.com/docs/product/L119_W.pdf)

At first glance, the T is not fitted perpendicular to the rising pipe. Maybe the tree support was not high enough to support the tree, maybe the pipe slid down due to improper supports. Check the decals and find the correct installation document even if you have a professional contractor make the repairs/adjustments for you.

Unfortunately, the decals on the tee and riser have faded.

 

[begreen]

16" is a very thick wall. What is going on in it to make it that thick? The person that installed it may have installed the outer portion of the thimble only. Perhaps that is because the wall was too thick? It looks like some exploratory surgery will be needed to find out exactly what was done behind the drywall. It could be that you will see the collar of the outside thimble section extending in and protecting the pipe for 3-4". If so, it will need its mate for the inside and perhaps a sheet metal extension fabricated to join the two? On the outside it doesn't look like the chimney pipe is well supported. I would add a wall bracket or two.

Just guessing but I'm wondering if that chimney cap is Supervent.

 

[joedirt16]

16" is a very thick wall. What is going on in it to make it that thick? The person that installed it may have installed the outer portion of the thimble only. Perhaps that is because the wall was too thick? It looks like some exploratory surgery will be needed to find out exactly what was done behind the drywall. It could be that you will see the collar of the outside thimble section extending in and protecting the pipe for 3-4". If so, it will need its mate for the inside and perhaps a sheet metal extension fabricated to join the two? On the outside it doesn't look like the chimney pipe is well supported. I would add a wall bracket or two.

Just guessing but I'm wondering if that chimney cap is Supervent.

First, the wall...it is an old farmhouse. I believe this portion was added on, but I can't guess as to when. Here, you can see the deep sill.

Exploratory surgery, I like the sound of that! (Although my wife might not. LOL!)

I agree, I think the exterior bracket is somewhat under designed. I might design one at work out of 12g and have it fabricated. Much more sturdy than this flimsy thing.

I'll investigate the Supervent lead.

 

[bholler]

It looks like the bracket is just not attached correctly It looks like it is pulling away from the wall. Nothing wrong with the bracket. I would guess you should have another bracket in the middle though. As far as the thimble goes you are just going to have to open it up and see what is there.

 

[joedirt16]

It looks like the bracket is just not attached correctly It looks like it is pulling away from the wall. Nothing wrong with the bracket. I would guess you should have another bracket in the middle though. As far as the thimble goes you are just going to have to open it up and see what is there.

I think you're correct, but I still feel like it could have some more girth to it. I don't like designing what I do to be just good enough. I like some safety built-in, too.

I was thinking that yesterday when I took the chimney down, as far as having a middle bracket in there.

Kind of stoked (no pun intended) to get home from work and cut up the wall around the existing pipe to see what is in there.

 

[bholler]

I think you're correct, but I still feel like it could have some more girth to it. I don't like designing what I do to be just good enough. I like some safety built-in, too.

The brackets are designed and tested to work with their system they have plenty of safety factor built in to them as long as they are installed correctly.

 

[joedirt16]

The brackets are designed and tested to work with their system they have plenty of safety factor built in to them as long as they are installed correctly.

Valid. I guess I'm just used to designing supports for heavier apparatus.

 

[bholler]

Valid. I guess I'm just used to designing supports for heavier apparatus.

I get it I typically over build everything but I have installed many chimney systems and I trust the brackets they have to go through extensive testing to get listed.

 

[joedirt16]

Sooooo.....very minor wall surgery reveals no thimble in the wall. Also, for some reason, this wall isn't nearly as deep as the adjacent wall, which is a plus.
The double wall pipe you see in the inside picture goes straight out through the wall, into the tee outside. You know, straight out through the fiberglass insulation, like you aren't supposed to do.

I guess my next question is, do I just buy a thimble, and install it per the manufacturer's instructions? Including clearing out the insulation, creating the dead air space between interior and exterior walls?

 

[bholler]

guess my next question is, do I just buy a thimble, and install it per the manufacturer's instructions? Including clearing out the insulation, creating the dead air space between interior and exterior walls?

Yes that is what you need to do

 

[joedirt16]

Yes that is what you need to do

Any recommendations? I've seen them online from $50, to over $200.

 

[bholler]

Any recommendations? I've seen them online from $50, to over $200.

the one to match the manufacturer of your chimney system

 

[joedirt16]

the one to match the manufacturer of your chimney system

Thanks a bunch!

 

[webby3650]

I'm almost positive that's a super-vent system. The only issue I see is that the support looks too low, making the connection between the tee and the first section of pipe a little janked. Get a thimble, you'll need to extend it with some sheet metal, the standard is only good for a 2"x8" wall. Most Tee brackets are reversible, I'm not so sure the super-vent one is. It's possible it's installed wrong to get some more projection out of it. Can't tell from the pic though for sure.

 

[joedirt16]

Since the minor surgery on the wall, something continued to bother me.

Why would they not use the inside thimble? Even though I've come across numerous shortcuts the previous residents took, surely they bought the whole kit. Right?

I cut the hole a little bigger, and I threw a tape into the wall. Numbers weren't adding up. Sure enough, 8" back there, you can see it.

It appears they did use the thimble, but only in to what appears to be a concrete backer board in the wall. (You can barely see the mesh in the shadows.) I guess since the wall is so deep, the thimble didn't telescope that far.

The other problem is, they didn't setup the wall supports according to the installation drawing...

I guess my only option is to rip out the wall, cut the studs since they didn't center it and I want the exterior location to stay the same so I don't screw up the siding, make a header (again, assuming they didn't center it between studs), create Figure 11 above, and then somehow figure out a way to create an extension from the interior wall thimble to the outside...I guess it's a good thing my brother used to finish drywall..

 

[begreen]

I think Supervent's thimble is for up to a 7" thick wall. That may have been why they fudged it and bailed on the inside part.

 

[joedirt16]

I think Supervent's thimble is for up to a 7" thick wall. That may have been why they fudged it and bailed on the inside part.

I think you're correct. Now I'm leaning toward just opening up the wall. At this point, it's probably the easiest way to make it right.
I'm still unsure on how I should "extend" the thimble. Maybe something like a 14"x14" sheet metal box going from wall to wall?

 

[begreen]

If this is 6" chimney pipe and the OD is 8" then a 12"x12" sheet metal sleeve would work. You want to keep a shield that keeps anything 2" away from the chimney pipe on all sides. You would still need a trim collar to finish the interior.

Or you could make an extension by pop-riveting a sheet metal band around the existing outside wall thimble inner lip. Then buy another Supervent thimble and just use the inner section. It's lip should slide into the extension band. That would provide the trim collar.

 

[joedirt16]

If this is 6" chimney pipe and the OD is 8" then a 12"x12" sheet metal sleeve would work. You want to keep a shield that keeps anything 2" away from the chimney pipe on all sides. You would still need a trim collar to finish the interior.

Or you could make an extension by pop-riveting a sheet metal band around the existing outside wall thimble inner lip. Then buy another Supervent thimble and just use the inner section. It's lip should slide into the extension band. That would provide the trim collar.

I was thinking about something like 12x12, or 14x14 duct work extending from the exterior thimble to the interior, fastened appropriately.

 

[webby3650]

I'm pretty sure they wanted a 14" rough opening for a wall thimble on 6" class A. All you need a piece of sheet metal, roll it around the existing thimble piece and rivet it into place.

 

[begreen]

Right you are. My Supervent instructions were from 2010 which didn't have framing instructions. I just downloaded the latest doc which is much better. It has framing directions which show a 14" x 14" opening frame size.

 

[joedirt16]

Right you are. My Supervent instructions were from 2010 which didn't have framing instructions. I just downloaded the latest doc which is much better. It has framing directions which show a 14" x 14" opening frame size.

I think I'm going to try and match the "stock" piece so it attaches in the same manner to the thimbles.

 

[edyit]

does supervent have anything like this?
https://www.walmart.com/ip/Selkirk-...ainless-Steel-Insulated-Wall-Thimble/21153044
that provides the clearance space you'd need