liner inside of 8 x 8 clay flue

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moey

Minister of Fire
Jul 12, 2012
1,455
Southern Maine
We have a 8 x 8 clay flue for our oil boiler and a 8 x 8 clay flue for a wood stove hookup. The flue for the boiler has a bend in it about 2-3 ft up from the boiler. Its showing signs of flaking a good amount. Can a liner be put inside a 8 x 8 flue? What about the bend?

I had someone come out and look at it a couple months ago they said they wouldnt be able to tell without climbing on the roof what its condition was, but if it needed to be replaced he would have to bust it out with a rotating tool. He mentioned he probably would damage the flue next to it so I would need both replaced.

Is it to difficult to put a liner down a 8 x 8 clay flue with a bend? or am I missing something.
 
I would have them run a camera down the flue to see the condition of it, if it has cracks then yes they will have to bust out the terracotta tiles to run an insulated 6" liner down.

If the terracotta is in good condition you "should" have no problem running a 6" liner down it, and if the bend is that bad you can look at putting a 5.5" liner down it.

But again I would highly recommend getting someone to run a camera down it for peace of mind.
 
I would have them run a camera down the flue to see the condition of it, if it has cracks then yes they will have to bust out the terracotta tiles to run an insulated 6" liner down.

If the terracotta is in good condition you "should" have no problem running a 6" liner down it, and if the bend is that bad you can look at putting a 5.5" liner down it.

But again I would highly recommend getting someone to run a camera down it for peace of mind.

This never came up when relining my 8x8"... we just dropped the 6" liner right down, despite the cracks.

Or rather, Hogwildz just dropped it down... all I did was film the fun.

Now, I had no bend, so maybe that matters a lot.

Why would one have to bust out the tiles to re-line?
 
This never came up when relining my 8x8"... we just dropped the 6" liner right down, despite the cracks.

Or rather, Hogwildz just dropped it down... all I did was film the fun.

Now, I had no bend, so maybe that matters a lot.

Why would one have to bust out the tiles to re-line?

I agree. I relined my 8x8 this past spring. zero issues... Did it myself, off the roof in under 20 minutes.
 
1. Installing liner into an existing lined chimney of good condition for wood burning
Insulation not required - any grade of stainless that is designed for this job is OK

2. Installing liner into a defective or unlined chimney
Insulation required with ANY stainless grade


As far as I understand NFPA 211, cracks in terracotta make the chimney defective.

Will this come back and bite you later if your house structure catches fire and the fire marshal rules it due to cracks in the terracotta and finds an uninsulated liner, dunno.

I tend to overdue things so I like to have proof the chimney was certified useable via a camera check, mine had cracks so I insulated my liner, now I sleep better at night knowing it is up to code.

Edit: Insulated 6" liner will not fit down 8x8, hence why it has to be busted out. Will an insulated 5.5" liner fit, maybe.
 
thanks for the information, I feel much more informed now
 
Feel free to ask more questions as the job proceeds. We want you to be safe as well as warm.

And welcome to Hearth.com!
 
I had a misaligned flue tile in the chimney for my oil fired boiler, so obviously failed mortar. Recommended fix was the same from two companies: install uninsulated 6" liner, then pour a thermal cement around it. I'm pretty sure they only used enough of the magic cement to build past height of defective tile, as the upper portion of chimney was in good shape.
 
Ok I had someone come out and inspect both liners the I'm a bit surprised by the results.

They indicated the flue for the oil boiler was deteriorating the last two feet which is where the flaking was coming from. They didn't seem to worried about it but did think I should get it inspected yearly. And if I ever replaced my boiler it would need replacing. The deterioration was several feet above the roofline.

The other flue that I wanted to use for a wood stove they basically indicated was like new only had a few fires ever lit in it.

However much to my surprise they indicated because my chimney was internal to the house it needed two inches clearance to combustibles. I dont have that so while they didn't indicate it was dangerous they in good faith good not install a wood stove in the flue. So I seem to be back to completely knocking out the flues again and insulating them.

They did suggest the possibility of a 5 inch liner insulated but that I basically would be limited to 1 or 2 stoves on the market. The flue is 21 ft.
 
Check out duraliner which is preinsulated. It's made for this type of installation.
 
Check out duraliner which is preinsulated. It's made for this type of installation.

Do folks use the 6 inch duraliner pre-insulated in a 8 x 8 clay liner ( inner dimensions 7 x 7 ) seems like a tight fit although the install directions say 7 x 7. Its a straight shot no bends.
 
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