Is flexible liner insulation needed??

[Tyannt]

A Hello to everyone; yes new here and needing enlightened!
My "Interior masonry chimney" ?? crown was all cracked up from the previous owner.
Chimney runs through the garage, opposite side of the living room where the fireplace is.
Open fireplace, oil burning boiler furnace "Beckett" below in basement.
At least the top 3 terracotta flues are loose from the bad crown shifting and I can
fix those but thinking of installing a flexible liner.
Question is... Furnace flue is 8. 81/4 square, good shape other than a few lose
at the top "that I know of". If I install a flexible liner down the inside of the terracotta
flue, and the flues are at least 4" away from the inside of the chimney wall.. Do
I need to do insulation wrap on the new liner?

I have a newfound respect for chimneys!!
Appreciated !

 

[begreen]

If this is for the oil furnace, probably not. Use 316 stainless for the liner.

 

[Tyannt]

If this is for the oil furnace, probably not. Use 316 stainless for the liner.

Thanks for the reply begreen! Yes, an oil fured burner... I have been reading about liner types
and had come to the conclusion 316Ti stainless flex was a good choice. Might I ask if that same
type is appropriate for the fireplace as well? Same scenario only it uses 8.5 x 12.5 terracotta flue.
As much as I've read, still alot to understand so that's why I'm here!!

Something of concern to me is... it's impossible, without calling in someone who can re-mortar
any of the lower tiles that I can't reach from the chimney top, is that going to be a problem
installing an unwrapped/insulated liner down the fireplace flue tiles? Or, is it a necessity to use
insulated liners regardless?

While I can understand the reasoning for insulated liners, where needed, am I wrong to think
that insulation is mainly needed when it's an exterior chimney? Correct me if I'm wrong!
May have my terminology all wrong Lol

Much appreciated!

 

[chimneylinerjames]

1/2" insulation is required for a solid burning appliance, wood and coal. This is to maintain the UL listing. This is required if there are any imperfections in the flues.

For liquid and gas burning appliances, insulation is not required if you are installing it inside a masonry chimney. But it always increases draft.

 

[Tyannt]

1/2" insulation is required for a solid burning appliance, wood and coal. This is to maintain the UL listing. This is required if there are any imperfections in the flues.

For liquid and gas burning appliances, insulation is not required if you are installing it inside a masonry chimney. But it always increases draft.

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Thanks for the reply!

1: If I use uninsulated flexible for my fireplace, inside the 8.5 x 12.5 terracotta flue, can I fill
the void with vermiculite/perlite mixed with portland, instead of the "wrap"? I read that if I
insulate that way I can always remove the liner if the need arises, and save the expense of a
wrap which reduces my liner size.

2) Code says chimney must be minimum of 24" above highest roof peak within 10' horizontally... Does that code mean " Top of the flue" or "top of the exterior chimney brickwork"?
All the drawings I've viewed show that height is to the top of the "Flue"

To all, appreciate the help and advice!

 

[chimneylinerjames]

Code says chimney must be minimum of 24" above highest roof peak within 10' horizontally... Does that code mean " Top of the flue" or "top of the exterior chimney brickwork"?
All the drawings I've viewed show that height is to the top of the "Flue"

It means where the flue gasses exit, so the top of the flue.

The pour down insulation will work.

 

[Tyannt]

It means where the flue gasses exit, so the top of the flue.

The pour down insulation will work.

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Thanks again.. This forum is the Best! Without question it's the members that make it so!

 

[Fred61]

I used vermiculite pourable insulation on two 34 foot chimneys in 1980 and it worked fine until I sold the house in 2000. It was the stuff made for concrete blocks which is a smaller particle size than the normal hardware store variety.

 

[Tyannt]

Hopefully final question, well, about THIS project anyway!
2 flues in my chimney... fireplace and oil furnace. Flues are
next to each other all the way up the chimney, actually touching from as far
down as I can see.
Is this normal, and any possible concerns? House built in 1976..

 

[chimneylinerjames]

Is this normal, and any possible concerns?

No its not the norm, there should have been brick in between the flues. If you have liners in them, no reason for concern. You need to have 0 chance of possibility of those flue gasses mixing, the liners accomplish this.

 

[Tyannt]

Kind of thought it wasn't right! Seems a few things weren't the norm
in this chimney!

Someone mentioned a trick to re-mortar lower terracotta flues with
a BAG or something?? A mason mentioned that to me today when
I was in Home Depot but didn't elaborate... clues? Explanation? Video? Lol

 

[chimneylinerjames]

Hmm....remortar the flues? Maybe he meant remortar to brick joints. That you use a bag with after you grind out the joints. If the flues are damaged, you need to install a liner.

Here is a video of the pointing with a bag.

 

[Tyannt]

Thanks for the video but....I did mean remortar the terracotta flues!
Can't recall exactly but was told some contraption lowered into the flues,
could be some kind of bag with holes in it so that as you pull it up, it leaks
mortar out filling the joints in the flues where it's missing !!
Hmmm, racking my brain to figure this one out...maybe a board fairly snug
fitting in the flue that the mortar runs off to fill any voids?
Dam why didn't I pay attention!!

 

[chimneylinerjames]

They do have a system, not very popular in the states, seems more popular in Europe, of a poured in liner. They insert a balloon like tube down the chimney then fill it in with a concrete then deflate the balloon. Not something a homeowner can do himself.