I have a Defiant 1910 which has an 8" oval to 6" round reducer bought from retailer with stove when new. My 6" flue has worked great venting this stove. I can not burn it with doors open and screen in place with the 6" flue, that is only recommended with the 8" pipe. I wasn't going to ever burn it that way anyway. I don't see a problem.
I have the same set up. I went to the factory and the response I received was positive as long as the doors were not open during operation. I will get some more details and add to this when I find the correspondence. My stove is an 0028 early model I have been using all this season with no issues. My length is 21' The bigger issue at hand may be the insurance company covering the use of a wood stove in an out building, My company State Farm would not allow it.
This was my inquiry to VC...
Inquiry: Hello- the following is from an e-mail thread I sent to the manufactuer of the cimney pipe I intend to use for my 1986 Defiant Encore I just purchased as used from a private party. The manufactuer of the stove pipe and acessories is Duravent, the product I am intending to use is the DVL double-wall oval to round adaptor model #8670 , model #9045N ceiling support box, with model # 8674 chimney adaptor and model # 8647 telescoping double-wall pipe.
Please advise of any testing approvals on these products for use with my stove.
Hello - I am using your DVL product for a Vermont Castings Defiant
Encore wood burner Model #0028 Ser. #24209
The manual states a warning " Do not use double-wall chimney
connectors with the defiant encore unless they have been specifically
tested and listed for use with this product. Use of double-wall
connectors which have not been tested and listed for use with the
defiant encore may result in temperatures that exceed the limits set
by the test standards ANSI/UL 1482. A potential may result including a
house fire ".
Do you have any specific information that will assure me that your DVL
product is compatible with my stove?
I would appreciate the information you can provide.
Keith – At the time the early Encores were made (1986 to 1989), there was no appropriate double wall oval to round adapters available to fit the oval flue collar. We put the note in to prevent the use of double wall pipe because no proper adapters were available at the time of testing. We never tested for double wall pipe clearances until the Model 2190 in released late in 1991. You may use Dura-vent double wall pipe safely because they currently make a proper oval to 8” round double wall stove adapter. This pipe is more durable and better for draft than single wall pipe. However, you must use the single wall clearance table for the installation as the early stoves (models 0028 and 2140) were never tested for clearance reduction with double wall pipe.