Retrofitting a chimney with double-wall wood stove pipe

[/pine]

:thumbsup:

Another observation.
Whenever there is a gap or break in the flue that allows colder air to enter is exactly where the creosote will accumulate....

This is a fact...building a chase that can be insulated around a flue in any unheated space will help prevent creosote from condensing on the inner walls of the flue where it meets much colder air... just dead air space is better than nothing as heat from the pipe will warm the surrounding chase...

The only place we get a sticky creosote buildup is at the very top of the pipe at the spark stop cap...

 

[Lineman North Florida]

I installed a wood stove insert in my fireplace about 15 years ago, I reached up from inside the house and cut out the damper with a Dremel tool and sawzall, I used stainless steel 6" pipe with the last piece being flex, I put it down in the existing chimney from the top and on the bottom piece of flex I installed a 3/8 stainless steel bolt through the flex about 4" from the bottom, I then went down and opened the door on the wood stove and removed the baffles and burn tubes and reached up through the stove and grabbed the bolt in the flex and pulled in right down into place on top of stove, re-assembled, climbed back on roof wrapped fire proof insulation around the 6" pipe and installed the new chimney cap. It has worked to perfection for the last 15 years, But I couldn't have made it work with the small amount of room that I had to work with without installing that 3/8 bolt through that piece of flex pipe.

 

[BoylermanCT]

I installed a 6 inch SS flex liner in a 8 inch square tile fireplace flue for an insert. The hard part was cutting the damper. There was and is usually a step for the damper so it's not a straight drop. I strongly suggest insulating the flex with a foil faced ceramic insulation (only ceramic can take the temperatures) covered with a SS mesh sock. The thin flex gives up a lot of heat that you want. As will double or triple walled pipe. Insulation keeps the hot gases hot. A hot flue doesn't deposit soot on itself. A hot flue also draws very well on start up. I run a nylon brush through it every 3 or 4 years. (don't use a steel brush, it will penetrate the liner) Did it yearly for a couple years, but let your experience dictate your cleaning timing.

Ditto on insulting the liner. Makes it a little more unwieldly to install, but will perform better. Better to do it at the start than to not do it and wish you had! I did mine, and it was not difficult. Ceramic insulation comes as a blanket. You wrap the liner while on the ground, tie it on with think metal bands and hoist it up on the roof to drop down the chimney.