Insulation around the liner?

[Boris]

I'm installing a VC Merrimack into an existing fireplace with 25' chimney.
The fireplace / chimney is on the exterior wall of the house.
Do I need to wrap the 6" liner with insulation or not? 1/2" or 1/4".

I understand that keeping higher temperatures in the flue leads to better draft, but is there any downside?
Too much draft?

Thank you,

Boris.

 

[begreen]

The insulation is for safety as well. Most chimneys don't have the required clearance from combustibles. If there is any defect in the chimney it's a necessity. The insulation also keeps the flue gases warmer which can reduce creosote accumulation.

Be sure the chimney is completely cleaned (including the smokeshelf) before the liner is installed.

 

[double-d]

You'd be looking at the 1/2" insulation, and depending how you wrap it around the liner, could add 1" to 1.5" to the 6 1/4 OD of the Flex Liner.
Many of the Fireplace Flues are 10.5" x 10.5" or slightly larger