Reducing Flue Size

[TRichon]

Hello, I have an existing Vermont Castings Defiant 2550 wood stove vented into an existing chimney. The chimney was "lined" before I bought the house. They used an 8" flexible SS liner that does not reach the wood stove, and is not properly terminated at the wood stove. Currently, the smoke pipe from the wood stove enters the brick, unlined chimney, there is some amount of distance between where the smoke pipe enters, and then the liner starts. Once I figured this out, I obviously want to correct it. So my options:

Use an 8" liner and struggle to get installed properly (it will be tight)

Use a 6" liner, the install should be easier, and I would have space to insulate around the liner. Currently, the VC 2550 has an 8" flue connector on it, but I can get an attachment to reduce that directly at the stove to 6". I know it means I can not run the stove with the doors open, but I never run it that way anyway, so no loss there.

Is there any other reason I would not want to reduce the chimney flue to 6"? Length of the flue is approx 16'

 

[Woody Stover]

I'm not sure but I think that stove could be picky about draft; Reducing to 6" might not work well.
As far as the chimney, if you can find out the brand of the flex you may be able to get parts to extend from the maker that will match. Mixing brands is hit-and-miss.

 

[Jan Pijpelink]

BHoller must be at the mall tonight.

 

[BrotherBart]

The VCs do fine with a 16' flue and six inch pipe. As you say, they advise 8" if you burn it with the doors open.

 

[begreen]

6" should be ok as long as the stove is not run in fireplace mode, with the door open. An insulated liner is a good idea.

From the manual:
An Encore with an 8” (203 mm) flue collar is approved for venting into a masonry chimney with a nominal flue size of 8” x 8” (203 x 203 mm) or 8” x 12” (203 x 305 mm), and into a round flue with nominal flue size of 8” (203 mm). An Encore with a 6” (152 mm) flue collar is approved for venting into a masonry chimney with a nominal flue size of 8” x 8” (203 x 203 mm), and into a round flue with nominal flue of 6” (152 mm).

NOTE: When installed with a 6” flue collar, the Encore may not be operated with the front doors open.

 

[BrotherBart]

Same for his Defiant.

"The Defiant is approved for venting into a masonry chimney with a nominal flue size of 8" x 8" (200 x 200 mm) or 8" x 12" (200 x 300 mm), and into a round flue with nominal flue size of 8" (200 mm). A Defiant with a 6" (150 mm) flue collar adapter is approved for venting into a masonry chimney with a nominal flue size of 8" X 8" (200 X 200 mm), and into a round flue with nominal flue size of 6" (150 mm). NOTE: When installed with a 6" flue collar adapter, the Defiant may not be operated with the front doors open"

 

[begreen]

That was from the CFM manual for the 2550. I think they called it the Encore Defiant?

 

[BrotherBart]

The Defiant Encore was the 2190, 2140 & 0028. The 2550 was just an Encore. Far as I know. Which as we know ain't much.

 

[TRichon]

Yes, this is the 2550. I never burn it with doors open, so that is a non issue. I think that is my plan, 6" flue liner, which I should be able to get better insulation around, and it will be cheaper. I just wanted to make sure I wasn't overlooking something in going that route. Seems like 6" flue should be good with any other wood stove i may replace this one with in the future.

 

[begreen]

The OP says it's a 2550 so maybe it is an Encore and not a Defiant. Regardless, both can be run on 6" pipe with the aforementioned caveat.