pellet stove insert questions
I'm interested in getting a pellet stove insert, and I've started doing some research but I'm not confident I understand (or believe) the information I'm getting from some folks, so I thought there might be some installers of folks 'in the know' here who could help clarify.
Background: Fireplace/chimney centrally located in a house built in 1870. Fireplace/chimney is dilapidated, and chimney now terminates in attic (done during a previous re-roofing). I want to put in a zero-clearance (ZC) pellet stove insert, run ZC venting up through the old dilapidated chimney, then up through a collar in the roof and cap it as a new vent.
Harmon seems to have a good hardware/features reputation, but the local dealer is telling me that (a) all Harmon inserts are ZC, but harmon sells a seperate ZC "box" for their inserts. The box is too large for my existing space (maybe I could remove the firebrick), but that makes me think the dealer isn't familiar with his own equipment (and he can't do the full install, just the stove- given the complexity of the job I think I should have one person do it all to make sure the venting ends up exactly where the stove needs it). Can anyone here confirm whether the harmon inserts are ZC without that special box?
The Harmon was my top choice due to small size (the fireplace is very small), their claim that the ash box doesn't have to be cleaned as often and the stove can take even lower quality pellets without a problem, and I like the idea of being able to hook it to a room thermostat.
My other locally available options include a pelpro insert, which I can get locally through a hardware store, or quadrafire, through a dealer.
Another question, about the venting - what is the max temperature of the vent gas going into PL piping? I'm wondering if I need to get a triple wall vent pipe to get the ZC, or if there are better (and cheaper) approaches. Some installers are telling me they can just run PVL right up the old (dirty) chimney, but the PVL specs all say 3" clearance, and I don't want to run any risks in that old chimney.
Thanks for any advice,