2nd smaller Flue that goes to basement

[woodhog73]

Hello hoping to get some input on my 2nd smaller flue

So my masonry chimney on exterior house wall ( but passes through attached garage) has 2 flues. The big flue goes to my main level fireplace and hearth . I put a new insert in that with 6 inch flex liner. All set there.

Right next to that is a much smaller flue I believe 6x6 square. It goes down to the basement where there is a brick hearth ( no fire place) where the previous owner had a free standing wood stove. It's a partially finished walk out basement. Along the way to the basement the other guy punched a hold into the small basement flue to add a tiny stove for the garage. I mean tiny as in could only fit two 12 inch splits.

The basement and garage wood stoves are long gone. Actually basement stove I never saw and garage stove I scrapped it was falling apart. Scratch the garage off the list , the insurance doesn't allow a wood stove in the garage and I don't want one there anyways.

But I wouldn't mind possibly putting one in the basement.

My concerns are.......

1) the small flue is not big enough to get a liner in. The existing clay liner has cracks in it, small vertical cracks. I wouldn't use it as is although the cracks are so small it probably would be fine. Still safety is important

2) Any stove I use would have to have a 90 degree bend since the flue opening is on the side or vertical entry. So I'm thinking stove pipe up roughly 3 feet out of the stove , then 90 degrees into the flue. How would a stove draft and perform like this? It's a one level ranch so we are not talking about a lot of chimney here.

Thanks for any input

 

[Squisher]

If you mean like this? It'll draft fine. I'm around 21' or 23' can't recall for certain from stovetop to the top of my chimney. I do plan to replace my 90 with two 45's but not until I see a need to replace the pipe. If your tiles are actually only 6x6 you'll never get a proper liner in there without breaking out the tiles and I would guess your chimney has offsets in it like mine at the least to go 'around' the upstairs fireplace. Without breaking out and putting in a insulated liner you won't be up to code. You would be if your existing chimney had the required clearance to combustibles(most don't) and if the tiles are already cracked, that's not good.

 

[begreen]

I'm guessing that the tiles in the flue are probably 8x8. They will need to be broken out in order to drop down an insulated 6" stainless liner in the chimney. A certified sweep can do the job.

 

[Squisher]

Mine were 8x8 which is common around here I believe. If I remember correctly it puts the interior measurement of the clay liner at just under 7"s.

 

[bholler]

Mine were 8x8 which is common around here I believe. If I remember correctly it puts the interior measurement of the clay liner at just under 7"s.

yeah that is the norm and they need broken out to insulate many times even a bare liner doesn't fit

 

[woodhog73]

Yes the set up would look similar to yours in the photo.

I'll go measure the small flue again. Perhaps it is 8x8. It's for sure square. The bigger flue was a little bigger and rectangle so the 6 inch flex liner fit in it and the clay tiles were left in place.

If I have to have the clay tiles taken out that sounds expensive. I think the flue just runs side by side with the bigger flue.

They guy before me burned a stove in that flue for 30 years with no problems. However I'm to safety minded and with cracked flue tiles, I won't use it unless it's lined.

 

[bholler]

The bigger flue was a little bigger and rectangle so the 6 inch flex liner fit in it and the clay tiles were left in place.

Yeah but it wasnt insulated was it?

They guy before me burned a stove in that flue for 30 years with no problems. However I'm to safety minded and with cracked flue tiles, I won't use it unless it's lined.

Those small cracks can be much larger when hot. Also after that long i can all but guarantee that the mortar between the tiles has failed and you probably don't have the required clearance from the outside of the chimney to combustible materials. It needs an insulated liner.

 

[woodhog73]

Yeah but it wasnt insulated was it?


Those small cracks can be much larger when hot. Also after that long i can all but guarantee that the mortar between the tiles has failed and you probably don't have the required clearance from the outside of the chimney to combustible materials. It needs an insulated liner.

No the flex liner was not insulated. It just looks like a silver steel flex hose I'm not sure if those are insulated in the design ? I'm not actually sure what the insulation is made from ? I wish it were but the few times I asked the hearth store they just said I'd be fine because the clay tiles were being left in place. But I think there's enough room to shove loose insulation down between the clay and liner perhaps I can still accomplish this ?

On the one hand I think to myself well the clay tiles were build to burn a fire in, but then on the other hand it seems most people insulate the liners.

I didn't know that the cracks can get larger when hot. Without a doubt I won't use that flue without a liner. If I want to use a stove in the basement I'll have to deal with knocking out the clay tiles in the small flue.

 

[bholler]

On the one hand I think to myself well the clay tiles were build to burn a fire in, but then on the other hand it seems most people insulate the liners.

But was the chimney built to code to begin with? You need 1" of clearance from the outside of the masonry to any combustible material for in external chimney and 2" for an internal one. If you don't have that your chimney was not to code to begin with and you need an insulated liner.

 

[begreen]

Even if built to code, there is a good likelihood some other contractor may have violated it. Our furnace chimney was much newer than the house and was framed with 2" clearances all the way up. Trouble is that no one wanted the smell of a basement (and vermin) coming into the main living space so the flooring went up tight against the chimney. Same thing with ceiling drywall as it passed through up to the attic.

 

[woodhog73]

But was the chimney built to code to begin with? You need 1" of clearance from the outside of the masonry to any combustible material for in external chimney and 2" for an internal one. If you don't have that your chimney was not to code to begin with and you need an insulated liner.

I'll be the first to admit building construction is not what I'm trained at but here is what I can tell.

The chimney is technically exterior walled but it passes through an attached garage. It's a floor to ceiling large hearth so no clearance issues inside.

I went to look better at the cement block chimney in the garage. So it's attached to the house but there is some sort of different colored board between the block chimney and the actual side of the house that is seen in the garage. It doesn't feel like wood. So to my untrained eye there is actually closer to 3 inches clearance from the cement blocks to the exterior house wall ( I'm assuming this odd colored board is some non combustible material ) ....it's not wood it sort of reminds me of the material the baffle in the stove is made out of?

So that would leave just the chimney where it exits out of the garage roof. I cant see from on the roof it's covered in snow. But looking up ( no ceiling in garage just trusses) I can see the garage roof has what looks like a solid inch possibly more between it and the cement block chimney. I'd have to grab the ladder to measure it but it's easily an inch probably more.

Then the cement block exits the attached garage roof and is covered in bricks for appearance above the roof.

Unless I'm missing something I actually think this chimney may have been properly built as far as clearances.

Funny thing is the house was built by the original owner where you can see a ton of do it yourself stuff that wasn't so great. So nothing surprises me. For example there was a drop ceiling in the basement . I removed it as I don't like drop ceilings. All of the electrical junction boxes were missing covers!! Wiring was fine, twisted fine, but no box covers ! Defeats the purpose of a junction box if there were an arcing situation ! Who would do that ? So I put junction box covers on . No big deal problem solved. The list goes on.

But when it comes to the hearth someone really went over board. They built a beautiful hearth far bigger than what was needed with nice visual design work, both upstairs and downstairs in the basement. So that makes me think a professional actually built the original masonry fire place as opposed to a do it yourself person. Perhaps the mason was careful to account for clearances ?

Just a guess but I'm really not sure.

 

[bholler]

Well it is pretty rare for a fireplace and chimney to be a diy project but many masons do not follow or even know they are supposed to have that clearance. If yours does it would be one of the rare few.