Liner insulation

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I have a SS liner installed at the begining of last season into an interior masonry chimney. I do not have insulation.
I dont think I need insulation as I always have a fantastic draft. If I did want to insulate, Is there a loose material like rockwool that can be dumped in the top of the chimney around the liner? I remember when I was young we had a loose insulation in the attic that we used to call rock wool.

 

[MountainStoveGuy]

there is loose insulation, but its not rockwool, its a vermiculute mix.
You have great draft with the currnet set up.
That doens not mean in any way shape or form you will have great draft with the new appliance. Remember that flues are driven by heat. The more efficient the stove, the less heat is avalible for the flue. If this chimney is on a external wall, insulate it now, not later, you will be happy you did.

 

[pgmr]

I used an uninsulated SS flex liner for one season, then insulated it with poured vermiculite the next year. It did seem to improve the draft and was fairly easy to do. I would probably use perlite if I had to do it over. Perlite appears to be lighter, cheaper and not as water absorbent, should the upper block off plate ever leak.

 

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Where would you get the Vermiculite or Perlite? What brands are they? I assume not the stuff people use for potting plants.

 

[pgmr]

I got mine at a local garden supply place, so yes, the same stuff used in potting soil (minus the dirt). I don't think brand matters, just verify that it is ONLY vermiculite or perlite. You might want to test a small sample with a propane torch to verify it's non-combustibility b4 installation.

Just re-read your first post. You've got an interior chimney w/good draft now, so I wouldn't bother doing this if the masonry is in good condition, unless you got a more efficient stove that didn't draft well (unless you are currently getting a lot of creosote buildup). Insulating won't give you more heat to the room.

 

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I currently use a 1981 Coalbrookdale Coal/Wood no Cat or second Burn and am switching to VC Aspen. The Masonry Chimney has two liners on for the Boiler in the Basement and one for the stove on the first Floor. Interior Chimney no outside wall and about three stories tall.
I just want to be ready if I do encounter draft issues.

 

[MountainStoveGuy]

look at it like a math problem
Your current stove is x amount of BTU's and its Y amount efficient. That means that N is the amount of heat avalible for the chimney.
(X)(Y)=N

old stove
100 bts X 50% efficient = 50,000 btus avalible for draft.

New stove
40,000 btus X 70% efficient = 12,000 buts avalible for draft.

Using what you know about chimmeis and draft, you know that heat is the primary driving factor to running a chimmeny. And the example above is a common scenario. A 20 year old,. 100,000 btu stove will put out the same amount of heat as a modern stove half its size, but its also clear which will draft better, and also why its important to not consider the current stove drafting capability. The new stove will be complety different.