Chimney Piping Issues

[Cincy Rick]

Hi everyone. So glad to have someone to bounce some questions off of. I have a Lopi Insert and it's being installed in an existing masonry opening. The flue is 8"x8" most of the way and is a bit wider at the bottom.

Several years ago we demo'd the upper section of the chimney which was falling down anyway and had to go, in order to tie in a new room addition. We liked the hearth and fireplace so we only took the chimney down to the ceiling level on the first floor.

Now we want to install a wood burning insert.

The problem is with chimney liner and the connection of a liner to some Class A. I'm told there is no way to do this, so I am wondering what you folks my have to say about how I should chimney this insert.

The insert is designed to vent directly into the firebox but I don't want that at all. When I pulled the old stove out it was amazing how much debris was in there and I don't want that.

Here's a sketch of the layout.
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I'd be interested in how anyone would design a chimney for this insert. It's 8" discharge.

I wanted to use flex chimney liner to the top of the masonry and convert to class A above that, but I'm told there is no way to make the transition. Any ideas would be most helpful.

 

[webby3650]

It is possible to convert the 2 with the use of an anchor plate. The anchor plate would be secured to the masonry structure and then class a would continue from there.
The issue is that you'll never find this info laid out in an installation manual. There's too many variables to ever get someone to sign off on it. Thats gonna be your hurdle!

 

[Cincy Rick]

It is possible to convert the 2 with the use of an anchor plate. The anchor plate would be secured to the masonry structure and then class a would continue from there.
The issue is that you'll never find this info laid out in an installation manual. There's too many variables to ever get someone to sign off on it. Thats gonna be your hurdle!

That's exactly how I was intending to construct the chimney, however, as you said, no one will sign off on it. I have spoken to a really nice and very detailed lady named Kim at Dura Vent and she said that it can't be done. My question to her was how to make the connection at the bottom of the anchor plate. She of course had no info on that and said it was not tested or engineered by them and could offer no info.

So, never having done this before, my question would be: Is there a way to make a mechanical connection to the anchor plate, because, I won't be able to use the hanger method because of the size of my chimney flue. I will probably have a few issues even getting the flex in there.

Also, there are two different anchor plates I was considering. One is the one you are referring to, I believe, called the "transition anchor plate" and the other is just called an anchor plate. I was thinking that either one would suit my purpose, however there is a $100.00 difference between the two.

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[webby3650]

The real issue I have is that it's no longer an all masonry structure. If you were doing a freestanding stove in front of the fireplace I would have less issue with it. If there's ever an issue, you'll be on you own. That insert is only approved for a masonry fireplace, that's all insurance will focus on.

 

[begreen]

The other issue to keep in mind is that the maximum class A elbow angle is 30 degrees. Why not go straight up and follow the old chimney path?

 

[Cincy Rick]

The other issue to keep in mind is that the maximum class A elbow angle is 30 degrees. Why not go straight up and follow the old chimney path?

The old chimney path would now exit into a valley in the roof. I don't think that is the best place for a chimney. I have calculated the route and the 30 degree elbows work out perfectly to take me through the trusses and to the ridge. Total length of chimney will be approx. 27 l.f. including the elbows.

 

[Cincy Rick]

The real issue I have is that it's no longer an all masonry structure. If you were doing a freestanding stove in front of the fireplace I would have less issue with it. If there's ever an issue, you'll be on you own. That insert is only approved for a masonry fireplace, that's all insurance will focus on.

Webby, how would you tackle this problem?

 

[begreen]

Off peak venting can be done with a conventional flashing. Ridge venting can be done, but with a special flashing.

 

[Cincy Rick]

Off peak venting can be done with a conventional flashing. Ridge venting can be done, but with a special flashing.

It's my belief as a builder that venting a chimney in a valley is nothing but a debris accumulator, especially at my house where we have lots of trees and leaves. Anyway, I get the impression that you are suggesting that elbowing to the ridge creates some sort of a problem. Is this the case? I don't see an issue with it myself, but if there is one, would like to know.

It's also an esthetic issue with the presentation to the street.

 

[begreen]

Sorry for the mis-impression. If the offset solves the valley issue it makes sense. I was just pointing out that if the offset could end before the ridge the flashing solution is much more common. If not, there is at least one company that makes a ridge flashing for class A pipe. The sketch doesn't show the valley or other obstacles you are trying to avoid. You have a better mental picture of the situation.

 

[webby3650]

The only real issue is that it might not make it. A 30 degree offset from vertical is all that's allowed. Any long offsets like that will affect draft as well. Definitely avoid a valley.

 

[Cincy Rick]

The only real issue is that it might not make it. A 30 degree offset from vertical is all that's allowed. Any long offsets like that will affect draft as well. Definitely avoid a valley.

There will be one 60" section between elbows. I guess I should have showed that. There will be a 48" section off the second elbow as it transitions back to vericle and will occur right at the ridge, giving me better than 36" protruding above the shingles. Everything will be encased in a "Hollywood" chimney constructed of Hardy Plank siding and composite trim. I will fabricate copper flashings and chimney caps in my shop.

Here's a photo of the house. The chimney will exit just to the left of the octagonal bump out straight above the flag. You can see how it might not look so good in the valley, especially on the street side, which you can't see in this photo, but same horizontal locale as the ridge which travels left to right in the photo. Sorry not sure how to explain it better.

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