6" single wall stove pipe inside a 7" insulated chimney for increased draft??

[Lord Preston]

Hi. I have recently installed a Drolet Austral (first generation without bypass damper) in my garage and my draft appears quite weak. Some of the problems I know of are that I am using 7" insulated chimney going through the ceiling/roof and I should be using 6" as per the manual. As well my single wall stove pipe isn't a straight shot up.. I have a section (6ft of single wall) running about 30 degrees.. Also, minimum chimney height on this stove is 12ft.. from the top of the stove to the top of the chimney is about 15.5 feet and extends at least 2 feet above the peak of the roof.

Anyways.. In an effort to increase my draft I was thinking of buying some more black 6" stovepipe, and running that inside of the 7" insulated chimney.. Similar to a chimney liner?? It would basically sit right on top of the 6" to 7" coupler where my single wall meets the insulated chimney. I'm thinking this would effectively keep the whole system at 6" and hopefully help increase my draft a bit.

Just wondering if anybody has ever tried this.. or if there is something dangerous about this that I am missing?

Thanks

 

[begreen]

Is the 7" chimney already in? If not, use 6" all the way. Otherwise, I think you will see much better gains by using 6" double-wall stove pipe for the full length of the connector then transition to the 7" chimney pipe with an increaser.

 

[Lord Preston]

yes the 7" is already in.. I have an increaser transitioning from the 6" single wall stove pipe to the 7" insulated chimney.

 

[begreen]

Double-wall stove pipe will keep the flue gases much hotter. That will not only aid draft, it will keep the flue system cleaner, reducing creosote accumulation.