type L vent in chimney?

[pegdot]

Hi all! New around here but enjoying the site.

Something puzzles me and I was hoping that someone here could explain why type L vent is necessary when venting a pellet stove thru a brick fireplace. I can see the need for pellet vent in a thru the wall installation but since heat isn't really an issue in a chimney wouldn't single wall pipe work in that situation? Confused...

Peg

 

[Metal]

Why not just use a flexible liner?

 

[hearthtools]

If you are installing an insert
ONLY USE stainless steel
you dont need L vent unless you are installing a freestanding but you need to use stainless

we use L vent anyway but you could just run flex

We use flex around the damper only then adapt to L vent the rest of the way

 

[pegdot]

Thanks for the replies!

Let me ask another silly question...sorry no one around here has pellet stoves so getting any info is hard. On a run over 15' the manufactrer recomends 4" rather than 3" pipe. Would I be able to to run 3" or 4" past the damper and then switch to 6" pipe or would that compromise the efficency of the insert? We're switching from wood to pellet but I'm not 100% certain that we'll like the pellets so I hate to spend a lot of money on pipe that I'd have to replace if we decide to switch back.

Peg

 

[hearthtools]

We run 3" flex around the damper
then Adapt to 4" pipe the rest of the way

You dont want to go 6" because it will not draft as well and More ash will collect and bridge up in the 3-6 transition.

 

[Metal]

You can run 3" past the damper (see picture) and then use a 3" to 6" adapter (from the company that made you 6" pipe) to fit up to the 6". Not much ash should collect if you use an adapter like the one shown, as it funnels down to the 3" pellet vent.

 

[hearthtools]

I have not seen any of the funnel type made of stainless
ONLY BLACK

 

[stoveguy2esw]

i have to agree with Rod on this one , also , remember that stack temps in a pellet unit do not run very high compared to wood units, and expanding the pipe past 4 inch could run the risk of dropping stack temps into the condensation zone , which is not attractive especially when not using stainless components like that increaser, could cause rusting in that component leading to exhaust leakage inside the flue space. 4" stainless in most pellet stoves can be used up to 25-30 ft with most brands. note also that 4 inch "B-VENT" must not be used with pellet units either in a flue or exposed.

EDIT: i would think about maybe even running 4" from the TEE at the bottom , all the way up for ease of cleaning (provided that the damper area is large enough to accomodate it)