insulating liner with thermix?

[cspalding0926@gmailcom]

Putting in my smooth wall 20' liner as soon as thermix arrives. Has anyone used this and is this going to make liner replacement impossible in future? I have a 7×7 clay tile with a 6" liner, so wrap insulation is not an option.

 

[bholler]

Putting in my smooth wall 20' liner as soon as thermix arrives. Has anyone used this and is this going to make liner replacement impossible in future? I have a 7×7 clay tile with a 6" liner, so wrap insulation is not an option.

We use it all the time and yes you can pull the liner out if you are talking about the double layer smooth wall stuff you will probably have to unravel it out of the chimney if need be. But honestly with that liner in a 7 by 7 you will have no where near enough insulation to be effective and you may even have trouble getting your liner in there

 

[rdust]

I had a 7x11 flue and had to use a 5.5 liner, my chimney is 30' tall so it still has a good draft. If it's clay lined you should consider removing the clay tiles first.

 

[bholler]

If it's clay lined you should consider removing the clay tiles first.

that is what we do normally

 

[JA600L]

I have similar questions. My flue is a 7x12 and a local stove shop put a 6" liner in it. I was told it was a tight fit. Should I bother trying to put a product in there to insulate atleast the sides of the liner?

 

[bholler]

New
I have similar questions. My flue is a 7x12 and a local stove shop put a 6" liner in it. I was told it was a tight fit. Should I bother trying to put a product in there to insulate atleast the sides of the liner?

It can help but it will not give you the zero clearance to combustibles it is supposed to because you will not have enough thickness

 

[BrotherBart]

The sides you would insulate aren't the ones closest to the house/framing members.

 

[JA600L]

What is the zero clearance about? This is an outside chimney with the clay liner still in tact and inspected to be good still.

I am mainly interested in providing the chimney with a better draft. My first thought is to drop Roxul in there, but I have seen other posts where people were told not to do it.

 

[bholler]

What is the zero clearance about? This is an outside chimney with the clay liner still in tact and inspected to be good still.
I am mainly interested in providing the chimney with a better draft. My first thought is to drop Roxul in there, but I have seen other posts where people were told not to do it.

To meet code your chimney needs 1" of clearance from the outside on the masonry to any combustible materials. If you have this then you are in good shape if not you do not meet code

 

[mellow]

Just because you have an external chimney doesn't mean you couldn't have rafters or combustibles right next to terracotta, (some) builders will always find a way to shortcut things.

If I don't build it, I don't trust it.

 

[bholler]

Just because you have an external chimney doesn't mean you couldn't have rafters or combustibles right next to terracotta

Even a properly insulated liner would not fix that the insulation is only designed to work with 4" nominal masonry between the outside of the insulation and the combustibles if it was just the clay liner there would still not be enough protection.

 

[JA600L]

The sides you would insulate aren't the ones closest to the house/framing members.

Actually it is. This flue runs east and west. The house faces north and south. This is a complete outside chimney with 3 flues. It is built very well (house built in 77') and thick enough that the flues are not near combustables. I only use one other flue for the occasional fire upstairs . The liner is centered in the flue.

 

[bholler]

Actually it is. This flue runs east and west. The house faces north and south. This is a complete outside chimney with 3 flues. It is built very well (house built in 77') and thick enough that the flues are not near combustables. I only use one other flue for the occasional fire upstairs . The liner is centered in the flue.

They it should be ok. Technically it would not meet code but you should be pretty safe

 

[JA600L]

So you think I should get some insulation in there? If it's a benefit I will do it.

 

[bholler]

So you think I should get some insulation in there? If it's a benefit I will do it.

yes I think it will help quite a bit. It wont be quite as good as if you had it insulated totally correct but it will still help

 

[JA600L]

yes I think it will help quite a bit. It wont be quite as good as if you had it insulated totally correct but it will still help

Which product would you recommend using for this job? I am close to a lot of box stores and masonry places. Sorry for all the questions. I realize this was not done in the correct way professionally but I would like to do things right from here.

 

[bholler]

Which product would you recommend using for this job? I am close to a lot of box stores and masonry places. Sorry for all the questions. I realize this was not done in the correct way professionally but I would like to do things right from here.

At this point your only option really is thermix or some other ul listed chimney insulation mix there are quite a few brands out there

 

[mellow]

Make sure your blockoff plate is sealed good before pouring

 

[Wisneaky]

What is the zero clearance about? This is an outside chimney with the clay liner still in tact and inspected to be good still.

I am mainly interested in providing the chimney with a better draft. My first thought is to drop Roxul in there, but I have seen other posts where people were told not to do it.

Not all liners are the same. My Duraliner is rated zero to combustibles and can sit next to wood or masonry with no clearance needed. Even when I have internal flue temps of 600 degrees I can hold my hand on the outside and it is barely warm.

 

[bholler]

Not all liners are the same. My Duraliner is rated zero to combustibles and can sit next to wood or masonry with no clearance needed. Even when I have internal flue temps of 600 degrees I can hold my hand on the outside and it is barely warm.

It absolutely can not sit next to wood it needs the 4" of masonry between it and the combustible materials. It is an insulated liner not an insulated chimney and even those need 2" clearance to combustibles. But yes it does have zeroclearance to the masonry and then zero clearance from the masonry to wood with no additional insulation

 

[Wisneaky]

It absolutely can not sit next to wood it needs the 4" of masonry between it and the combustible materials. It is an insulated liner not an insulated chimney and even those need 2" clearance to combustibles. But yes it does have zeroclearance to the masonry and then zero clearance from the masonry to wood with no additional insulation

Sorry I should of added masonry next to wood.

 

[ChimneySaverVT]

Hello it may be to late but ..Do Not use the Thermix...
If you do not remove the tile liner you will not really be able to get much thermal in at all anyway. If you do remove the tile liner you will have plenty of room to wrap the liner with a 1/2 insulation wrap. Thermix cannot be cantered around a chimney liner so its a unprofessional installation.
Thanks

 

[bholler]

Hello it may be to late but ..Do Not use the Thermix...
If you do not remove the tile liner you will not really be able to get much thermal in at all anyway. If you do remove the tile liner you will have plenty of room to wrap the liner with a 1/2 insulation wrap. Thermix cannot be cantered around a chimney liner so its a unprofessional installation.
Thanks

I dissagree totally it can be done professionally if you know how and in some situations it is the right solution.

 

[kennyp2339]

I like the idea of the thermix, but what happens if you have a chimney fire or the cap rips off the liner and you have to replace the whole thing? doesn't the thermix set up like concrete?

 

[bholler]

I like the idea of the thermix, but what happens if you have a chimney fire or the cap rips off the liner and you have to replace the whole thing? doesn't the thermix set up like concrete?

No it sets up soft you can pull the liner out of it.