Vermont Castings Aspen C3 2022

[Todd]

Hey @30WCF your posts and data are amazing. I'm dealing with the Aspen C3 taking off on me even on the break-in fires. Second break in fire it got to 825-850 F -- hoping I didn't break anything by getting it that hot on just the second fire. Yesterday, fire #5 or 6, it really took off and my laser thermometer that maxes out around 860 showed "OH"; I didn't get my IR gun to see exactly how hot it got. After maybe 30 min, it was back down to 850 or so. Last night I loaded it pretty full of oak, maybe 1-2 smaller branches of yellow poplar (oops).

I need to take a look at the intake flap and chain; I might change it by a link or two to see if that helps.

I wanted to ask if you feel confident about this being true? Do you still feel that too much air under the logs is a big part of what's happening when the stove temps run especially high?

How tall is your chimney? Could be draft is too strong.

 

[mycelianhollow]

How tall is your chimney? Could be draft is too strong.

Good call; the stovepipe+chimney is total about 24-25' (45º A-frame-ish roof). Do you think the draft could be so strong that moving it a link or two wouldn't work? (And if so, does that mean it's time to think about something like a manual damper on the outside air intake? I've wondered about that as a solution too.)

 

[Todd]

Good call; the stovepipe+chimney is total about 24-25' (45º A-frame-ish roof). Do you think the draft could be so strong that moving it a link or two wouldn't work? (And if so, does that mean it's time to think about something like a manual damper on the outside air intake? I've wondered about that as a solution too.)

I was thinking stove pipe damper first before messing around with the air. These stoves were tested on the equivalent of a 15’ chimney with perfect draft. 25’ is pretty tall and probably sucking like a Hoover at times.

 

[mycelianhollow]

I was thinking stove pipe damper first before messing around with the air. These stoves were tested on the equivalent of a 15’ chimney with perfect draft. 25’ is pretty tall and probably sucking like a Hoover at times.

VC says the Aspen C3 was not meant to be used with a stovepipe damper. I'm not inclined to give them a reason to void my warranty or anything like that. 🙁

 

[Burnin Since 1989]

VC says

I believe it's the EPA that says don't use a flue damper with a Cat stove. I looked at the Vermont Castings • Encore Model 2040-CAT-C Installation Manual_R15 • 06/25. On Page 13, when reading about chimney height and drafting issues.

In that case, the unit may experience short burn times, difficulty controlling the burn rate of the stove and the potential for overfiring. In the past, stack dampers could be recommended in these installations, but manufacturers are no longer permitted to specify these on EPA Certified models. The chimney system should be carefully reviewed and draft tested (if possible) prior to installation of this unit.

I don't know what they specified in other install manuals, but in this one they never say you "can't".
Maybe someone with more knowledge on the subject might be able to explain why the EPA doesn't want a flue (or as VC called it) "stack" damper being used with a catalytic stove certified to 2020 standards.

I'm going to guess, since it's the EPA, it is that it likely increases emissions.

I've been using a flue damper in my non-cat woodstove for a long time. I will tell you that when partially closed it increased my burn times and if used properly, I don't see any smoke coming from the chimney, just like if it was open.

Curious what others with VC stoves have in their install manuals.
Edit: I realize the Aspen and Encore are different stoves, but all I have is the Encore manual as reference.