Chimney Liner Insulation

[VASteve]

Good Morning,

I received a few quotes for 6" stainless steel liners in my 23' exterior chimney. Most quotes are around $4,000+ and not financially viable right now. One company quoted $3k for an uninsulated liner. I currently have a 8.5x13 (7x11 inside) clay/terracotta liner. Overall, it is in good condition with a few minor hairline cracks (see photos). There are clearances between the clay liner and cinderblock walls of at least 1" all around, which seems to be to code for an exterior chimney. I verified this when I rebuilt the crown at the top.

Given that there are only a few hairline cracks and the liner is otherwise in good shape. There also seems to be appropriate clearances around the existing clay liner. Is it acceptable for me to just drop a 6" uninsulated liner into the clay liner?

I can even slightly ovalize it and add vermeculite insulation mix after it is in. I just don't think I'll be able to fit a liner and insulation blanket around it without breaking out the clay liner (prefer to keep this intact). What are my options here?

 

[begreen]

If clearances are met then yes, the liner could be uninsulated. It may not draft quite as well as insulated and there may be more creosote accumulation, especially if the stove is a catalytic.

An oval liner is what is typically installed in this dimension chimney tile. It can have an insulation blanket applied on site. If the chimney is straight with no offsets, then a rigid, pre insulated oval liner could also be use. Duraliner makes this system. The other option is to bust out the clay liner and install a regular 6" round liner.

Pouring vermiculite after the fact is not going to help that much unless the liner has spacers all the way down to ensure that the liner has a 1" gap for it's entire length so that the vermiculite is evenly distributed around the liner.

 

[VASteve]

My spacing is similar to the image below (just with concrete block on the house side). Round 6" pipe goes through easily (I tested it with a 6.25" pipe I had). If I slightly ovalize it, I think I will have about .75 inches around the entire thing if I decide to pour vermeculite down later. This is the most affordable option, but maybe I should just bite the bullet and buy the oval pipe.

Do I need to be able to access the cleanout cap (image 2) or can I just fill in everything above and below with insulation?
Do I need insulation for a chimney inspection? I have pictures with the crown off and you can see clearances.

 

[bholler]

My spacing is similar to the image below (just with concrete block on the house side). Round 6" pipe goes through easily (I tested it with a 6.25" pipe I had). If I slightly ovalize it, I think I will have about .75 inches around the entire thing if I decide to pour vermeculite down later. This is the most affordable option, but maybe I should just bite the bullet and buy the oval pipe.

Do I need to be able to access the cleanout cap (image 2) or can I just fill in everything above and below with insulation?
Do I need insulation for a chimney inspection? I have pictures with the crown off and you can see clearances.

View attachment 316841 View attachment 316842

That's not where you need clearances to meet code. You need clearance between the outside of the masonry structure and any combustible materials.

 

[VASteve]

That's not where you need clearances to meet code. You need clearance between the outside of the masonry structure and any combustible materials.

This is good to know, I didn't realize this was to the outside. So it looks like I should really try to install with insulation. Do you think ovalizing a 6" pipe to 5" on the small side will affect the draw too much? I'm surprised how much more the oval pipe is to buy!

 

[bholler]

This is good to know, I didn't realize this was to the outside. So it looks like I should really try to install with insulation. Do you think ovalizing a 6" pipe to 5" on the small side will affect the draw too much? I'm surprised how much more the oval pipe is to buy!

You can typically buy a 6" equivalent oval liner