Insulating chimney for inserts?

[mikestod]

I was reading in another thread about a suggestion to insulate the chimney opening in a fireplace insert application. How many other members with inserts have blocked off the bottom of their chimney with insulation? I'm just wondering if this is something necessary, as the installer did not block it off or suggest that I might want to do it. Are there any special considerations one should take in doing this, or reasons not to? I would be concerned about insulating around the stainless liner, for one... If it is recommended to, do you just use paperless fiberglass batting?

 

[chimneylinerjames]

You should have the liner insulated. But the blocking off around the liner where in enters the smoke chamber is optional. It is not required for safety at all but it will give you more heat into your home if you have it blocked off. DO NOT use fiberglass insulation. Use a fire rated insulation such as Roxul.

 

[mik_kane]

You should have the liner insulated.

Is it necessary to have the liner insulated on a pellet insert? And why?

 

[chimneylinerjames]

Well lets see what other have to say about this. UL states that appliances that burn solid fuel need insulation if the flues are not in perfect shape to have 0 clearance to combustibles. Meaning if you have a crack in a flue you will need the proper spacing between masonry and any combustibles.

On the other hand, a pellet stove runs cooler than raging wood stove. Also the 3" or 4" liner will probably have an air space between the chimney mos of the way up the chimney.

A block off plate, or stuffing insulation around the liner in the chimney for a pellet stove will not give you much more heat. For a wood insert you would notice a large difference, not a whole lot with a pellet stove.

 

[mikestod]

On the other hand, a pellet stove runs cooler than raging wood stove. Also the 3" or 4" liner will probably have an air space between the chimney mos of the way up the chimney.

Right, which is what I have in my arrangement. I have a standard brick chimney, Both my stainless steel liner and my aluminum OAK pipe both run up the chimney, with nothing but air in between. I couldn't see a reason to insulate the liner the whole length of the chimney but was more curious if an insulated block-off plate at the base of the chimney is a good idea or a bad idea?

 

[chimneylinerjames]

The block off plate in your situation won't provide much of a benefit. It may reduce some draft up the chimney, but the chimney should be sealed off on the top anyway. It won't hurt to have one but don't expect any noticeable difference.