New chimney pipe inside old chimney pipe?

[fordtrucknut]

Im looking at installing a pacific energy FP30 zero clearance wood stove in place of a coleman zero clearance fireplace.
The installer wants to run the new supervent Class A flue up the inside of the old flue (removing the inner stove pipe)

Is this a feasible way to do it? I know the outer section of stainless flue currently in the house is 12" and the outside diameter of the supervent is 8"

 

[begreen]

I would not want that. What is the intent? Are they trying to save you some money on the top flashing and cap replacement?

What is the ID of the old Coleman chimney pipe. If this is triple wall then it could be 8" ID.

 

[fordtrucknut]

1. yes, he said it would save me about 1500.00-2000.00 on install costs, the new cap will actually be placed on and placed inside the old cap,
2. the I.D. pipe of the coleman is 8" SS that is placed inside a 12" I.D. SS pipe, with nothing but air gap between the two, he will be removing the 8" pipe completely, (it just slides out of the outer pipe) and putting the class A in its place ( the class A is 6" I.D. with and 8" O.D.)

My understanding by how he explained it was I would essentially have a triple wall pipe, ( the solid pack insulation of the supervent and an air gap between that and the 12" pipe)

also like to note this is a strait shot up chimney. no bends at all in the system.

similar to whats in the house, inner pipe just slides right out.


what is going into the above outer pipe.

 

[fordtrucknut]

I also have one of these cathedral support boxes already installed too. that fits for the 12" pipe.

 

[bholler]

I would not do it if I were you you would be much better off to just take it out and start over. How is he going to support the new chimney? How is he going to seal the gap between the two chimneys at the top? I would not let him reuse the old cap at all that just sounds like a maintenance nightmare.