Switching from Wood Stove to Pellet Stove - 10" Pipe to flue

[nhmtb]

Hi,

I am looking to vent a new to me pellet stove where my old wood stove was located. There is a 10" round hole to the flue lined chimney.
Wondering if anyone has any experience or suggestions reducing the 10" down to 3" or 4" for the pellet stove vent.
I see a lot of 6" to 3" but figuring I am going to need a couple of reducers to accomplish venting. Alternatively it might be easier to run flex pipe through a collar up the chimney - 15 or so feet rise.

Pellet stove is a Harman XXV -

Thanks much,
Bob

 

[Washed-Up]

Here’s an install I did of a P61-A using a 10” existing setup