installing wood stove into old coal fireplace

[[email protected]]

Hi, I'm new here- so bear with me! Anyone have suggestion for lining chimney that is 4" x 16" (some bricks loose and narrows in a few places)?
We want to puta tiny Jotul (Nordic F 100) wood burning stove into our 1920's bungalow that has an open fireplace (brick- no liner, no damper yet).
We are not sure if this is safely possible to do. We've been told by installer who inspected it that our options would be to ovalize a round liner,
go with gas, place somewhere else using a pre-fabricated chimney or knock out some of the brick to make it large enough. We called a chimney sweep for a second opinion and they seemed to think we could get a rectangular liner- and the concern would be if it would give enough draft. Seems like the Nordic manual says to have at least "6 for liner. Any suggestions would be great- we don't want gas- would defeat our purpose of avoiding using our gas heat and we don't have a huge budget.

Thanks for any thoughts.

 

[NeoJotul]

Coincidentally, I just installed an F100 into an old coal-burning fireplace on Tuesday. As we both live in 1920's bungalows in the same city, we're likely neighbors.

I'm sending you a note with the name of my local hearth god, whom I suggest you contact, should no one here be able to resolve your issue. The guy can make anything work wonderfully.

 

[Gooserider]

There are several online chimney supply places that I've seen mentioned favorably here. Do a search on "Chimney Liner Sources" They can sell a variety of sizes of liner, what you will need is probably something like an ovalized 8" or possibly something that was made in a rectangular or oval shape to begin with, and that has approximately the same cross sectional area as a 6" ROUND liner (You can't just ovalize a 6" liner, as that would reduce it's cross section to much) However it is definitely doable.

Welcome to the hearth for both of you....

Gooserider

 

[[email protected]]

Thank you for your thoughts- we really would love to install this wood stove but safely of course. I also couldn't get a good handle on whether the installer was steering to gas or pre-fab chimney because of safely or trying to up-sell us something.

 

[swestall]

I'm with Goose: get an ovalized 8" for that chimney, at least double wall.

 

[[email protected]]

Hi, sorry for the late response..I've been out of town. Thanks for your input- can you clarify what you mean by double wall- do you mean the insulation or the liner?
Thanks!

 

[Gooserider]

Some types of rigid liner are double wall, and as such don't need an insulation jacket on them. The advantage is that they are often smaller in outside dimension than a single wall liner with insulation jacket would be. The downside is they can't be ovalized or otherwise reshaped in the field, they have to be made the way they'll be used.

The key things you have to find out are what condition the flue is in and what size it is.

Since you have a brick flue, w/ no clay liners, you will need an insulated or double wall liner to bring it up to NFPA 211 standards, which is the code that specifies what you need to burn safely.

You said it is currently about 4x16, which is 64 square inches in cross section, and you need to fit a stove that calls for a 6" round flue, or some other shape with about the same cross section area, about 28 square inches.

On paper, a 2x14 interior dimension would give that, but I don't know if that is a size that can be affordably had. The basic problem is that you have a seriously oddball size and shape flue, so it will be a challenge to make it work. If you do a search on "chimney liners" you will find several vendors that are frequently mentioned, I would see if any of them can help you.

I heard mention of knocking out bricks - generally this will be a bad idea, as the remaining masonry may not be strong enough, and / or may not offer enough isolation from adjoining parts of the structure for fire protection.

Your other good option, which may turn out to be less expensive is to run a new 6" Class A chimney, either in a different place, or knocking down the existing chimney and putting the new one in it's place. That will get you into the world of standard parts, which are usually less expensive, and definitely easier to come by.

Good Luck,

Gooserider

 

[[email protected]]

Thank you for the information.
I will look into the Class A chimney- I guess I would be surprised if it were less expensive (than knocking out brick you mean). We are having someone come back and take a look- he
said he will bring a 2x4 to see if it will go down our chimney as a test to see if a 4" liner could work. We did the math and an 8" ovalized liner (4"x8") looks to do the trick as far as area. I didn't think there was a liner smaller than the 4" with the correct alloy for wood burning- I read that AL49-2C. As far as insulating we were told we couldn't fit in around the liner but could use vermiculite and seal around the flue. Do you have any thoughts on flexible verses rigid liners in the case of smaller chimneys such as ours?
Thanks again for your help and thoughts!

 

[Gooserider]

Thank you for the information.
I will look into the Class A chimney- I guess I would be surprised if it were less expensive (than knocking out brick you mean). We are having someone come back and take a look- he
said he will bring a 2x4 to see if it will go down our chimney as a test to see if a 4" liner could work. We did the math and an 8" ovalized liner (4"x8") looks to do the trick as far as area. I didn't think there was a liner smaller than the 4" with the correct alloy for wood burning- I read that AL49-2C. As far as insulating we were told we couldn't fit in around the liner but could use vermiculite and seal around the flue. Do you have any thoughts on flexible verses rigid liners in the case of smaller chimneys such as ours?
Thanks again for your help and thoughts!

Most of the good chimney liners that I've seen have been made with 316ti alloy, I'm not sure that that AL49-2C stuff is. Doing an 8" ovalized to 4" sounds like it will work as long as the liner will retain it's structural integrity when squished that much, and if vermiculite is all you can fit, that's what youll have to use for insulation.

In terms of flexible vs. rigid, it isn't a big deal, normally the rigid is a little easier to clean, and in theory may draft better, but the differences are minor. In some cases the rigid can be smaller in OD than the same size of flex, but again that doesn't sound like a big deal in your case. The key issue is what is the best solution the guy you have looking at the setup can come up with to stuff down the flue.

When you have a big wide flue, you have the luxury of debating what all the different options are, and which one is slightly better than the others. When you get into an oddball tight squeeze situation like yours, it comes down to the best answer being "whatever fits"

Gooserider

 

[[email protected]]

Then we will see what he says- thanks for clearing that up. I will post what our solution (if there is one) will be after we get the second look.
Thanks again, and happy Thanksgiving!

 

[[email protected]]

Just to update- we are able to install our small Jotul. Evidently the narrow brick flue (4"x16") was a chimney within an existing chimney- so they ended up taking the inside bricks out by busting a hole through the chimney inside our attic. The inner chimney brick was so loose they were able to knock it loose/break it up. They put a stainless steel flue in and still have to come back to finish patching the chimney hole etc. They have not insulated and I don't know if the standard 6" liner is double walled- should I make sure they insulate still? I worry only because they don't explain well to us what they going to come back and finish and this has been such a slow job on their part.
Thanks for your help, again!

 

[jtp10181]

Uhh... sounds like your existing chimney was not lined at all with clay tiles? If that is correct then a 1/2" insulation wrap (or equivalent) is usually REQUIRED for the chimney system to meet UL 1777. It is possible they installed a double wall pre-insulated liner but its not likely.

 

[[email protected]]

Yes, I was wondering about whether that's what they installed- but they haven't explained it either way so I will inquire tomorrow. Thank you for the specific information
though- so I know what I'm asking about!