We do not recommend long runs of stovepipe to increase heat dispersal. Longer lengths of stovepipe, or more connecting elbows, than necessary increase the chances of draft resistance and the accumulation of creosote buildup.
"...Than necessary." I believe they are referring to installs where people intentionally run the stove pipe extra distance to extract more heat, like horizontally across the room. They aren't going to say what a "too long" run is because there isn't a definitive answer. It depends on many factors....
What is a long run for a 1 cubic foot stove? 5ft? 8ft? 10ft? Canada says 10ft without any concern about stove size. I would estimate that 10ft is too long for a 1 cubic foot stove to drive without risk of creosote buildup. Would you agree?
What is a long run for a 3 cubic foot stove? Is it the same? Is this a clipboard warrior issue or a practical issue? I would argue that there isn't a clipboard we can point to with a definitive answer. only "rules of thumb/guidance/recommendations."
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Other members of the household should be able to operate the stove with basic instructions. The addition of more dampers makes instructions more confusing and more difficult to remember for non-enthusiasts....
Operating Instructions (and observations) with double wall: Bypass CAT to open door and start fires. For cold starts, leave door open until firebox is ingulfed in strong flame and draft produces thunder/roar sound. Open Air control all the way then close door. Engage the CAT when target EGT's are reached on start-up (600F), and any time door is closed thereafter. Run with air control wide open until 600F EGT is achieved on startup and subsequent fuel loads. Adjust down to 1/8-1/4" open for large fuel loads, 1/4-3/8" for smaller fuel loads. Check and adjust air control every 30 minutes to prevent EGT's from going over 800F otherwise the stove may run-away and overheat regardless of air control position, If <1/8" on large load or <1/4" position is selected on the air control to prevent over-firing the stove, continue to check and adjust air every 30 minutes to prevent primary/secondary combustion from being extinguished during the gaseous phase of the burn, which can lead to back-puffing and chimney deposits which could be dangerous. Good Luck. Don't enjoy. Be nervous and paranoid that the stove could overheat or explode. Babysit it constantly. Good luck sleeping or leaving the house.
Current operating instructions (and observations) on single wall are simple: Bypass CAT to open door and start fires. For cold starts, leave door open until firebox is ingulfed in strong flame and draft produces thunder/roar sound. Open air control all the way then close door. Engage the cat when target EGT's are reached on start-up (600F), and any time door is closed thereafter. Run with air control wide open until 800F EGT is achieved on startup and subsequent fuel loads. Adjust down to 1/4-3/8" open for large fuel loads, 3/8-1/2" for smaller fuel loads. EGT's will self-regulate from ~800F down to ~600F throughout the gaseous part of the burn cycle with no adjustments required. 800F+ EGT's will be more aggressively cooled and condensed by the single wall pipe, providing a self-correcting draft-control for excessive EGT's. No manual corrections required. The minimum air setting of ~1/4-3/8" (depending on fuel load) is sufficient to maintain primary/secondary combustion through the gaseous part of the burn, which prevents back-puffing and creosote/soot deposits in later stages of the burn as the fuel transitions from gaseous to coaling burn phases. Enjoy the fuss-free clean fire. Sleep well.
I don't know what the damper on double wall situation would look like specifically for controls, if it would require frequent adjustment or not... I do know it requires manually controlling and adjusting a 3rd thing and I question whether it would produce the sort of fuss-free results we get now on single wall. I know I would get less heat out of the system with double wall and a damper.
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The double wall was so likely to cause over-fire conditions, the "solution" was often to use smaller fuel loads and more restricted air settings, which can also lead to cooler fires and creosote/soot deposits. We generally tried to prevent the stove from ever going over 700F EGT otherwise it could snowball out of control.
The double wall that I removed from the system had about 12 weeks of burning on it since it was previously swept (end of last season, beginning of this season), and had about a 1/4-5/16" layer of soot (black ashy) deposits. Not unexpected for the resin-rich wood we burn here, definitely needed to be swept, but trying to keep the stove from over-firing was likely contributing to worse conditions for deposits in the chimney system.
Since transitioning to the single wall 8 weeks ago the soot deposits on the single wall are 1/16"-1/8" thick. We are getting more and more comfortable allowing the stove to run higher EGT's now, as we learn that it can do so safely without snowballing out of control.
Given the type of wood we have here, some full of resin, it probably makes more sense to aim for stronger, faster, hotter burn cycles with over 750F EGT's during the most active part of the burn. This would be the key to keeping soot deposits under control. If I'm going to run the stove hot enough to properly process the resin, I'd like to recover some of that heat!
Lots of variables... ALL things considered, I think that I'm better off driving 600-900F EGT's into single wall than 400-700F EGT's into double wall, and while there's likely a way to drive high EGT's into double wall with a damper to better process the resin without over-firing, that seems like a waste to me. Time will tell.. My house my experiment. I have a very handy Wohler Viper chimney sweeping tool and will keep a close eye on the deposits. If I need to sweep a few times a season that's not a big deal... Based on current observations I would say that the single wall driven hotter will require less sweeping than what we were doing. I think I might install a temp probe on the pipe up near the support box so that I can observe the drop in EGT's over the length of pipe and report back findings to the forum. It would be easily visible from up on the loft..
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Apologies to Dgrant09, this has gone off topic a ways. Though I believe still applicable to the larger picture here. I think the conclusion for your particular stove situation, with the clearances and such involved, is that a damper is the only good option to help pull your stove temps down into the reasonable range.
