Almost every thread I have read about double wall versus single wall stove pipe states that flue gasses cool less with double wall, and if conserving stack temps to minimize creosote condensation is important, then double wall pipe should be used. Has anyone made any real world temperature measurements to document the difference? I'm wondering how much warmer flue gasses would be after 10 ft in the two types of pipe? I know that variables like heat input into the pipe, temperature of the room, pipe diameter and gas flow would influence the results. No need to go into distance to combustibles and longevity. Thanks.
Temp loss in single wall vs double wall stove pipe
- Thread starter sleddogs
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Someone wrote this up some time ago with a longer run of pipe. The temp drop was larger than I would have expected. It was considerable, like >100º. Last year there was a poster that was having creosote buildup and draft issues with a long single-wall run that had a portion (correctly pitched) of horizontal before the ceiling support box. The solution there was double-wall stovepipe. If you or someone else would like to setup this project, test and report back that would be great.
In the meantime search prior threads on the topic. Here's a starter:
www.hearth.com
In the meantime search prior threads on the topic. Here's a starter:
radiation of heat from stoves and pipe
I started talking about this in another recent thread and realized I was probably hijacking the thread and this probably deserves its own thread. We were talking about possible efficiency loss by using double-wall connector pipe, so I wanted to try to calculate what this would be. That is...
www.hearth.com
I did a number of google searches to see if data exists to support the generally held statement that temperature losses in double wall stove pipe are less than in single wall and couldn't find anything. I did see the post that begreen mentioned showing some fairly high temperature differences in single-wall pipe that spanned over ten feet. It does seem intuitive that a 1/4 inch air gap in double wall would lower temperature loss over a single wall pipe, but if the goal is to keep temperatures at the top of the flue above 250F with an EPA 2020 stove during cold temperatures, wouldn't installing Class A chimney below the ceiling and using the bare minimum of connecting stove pipe be a better solution? One inch of airspace with insulation seems like it would preserve temperatures much better than 1/4 inch without insulation. Most installations go with stove pipe to a chimney connector near the ceiling. I can see that as an advantage for recovering more heat with older stoves that put a lot of heat up the stack. I wonder if this is the best way to install more efficient stoves?
Last edited:
Yes, having class A almost to the stove would keep the flue gases hotter, but the look is unsightly to most people. Still, I have seen a couple installations done this way. Double-wall stove pipe is a compromise. It is slightly lossy, but not as much as single-wall. . Some cat stoves run a cooler flue so temperature loss is a bigger issue. For most non-cat straight-up installs with 5-6' of stove pipe this is not an issue.
Class A to the stove would also be very expensive. It’s not 1/4”, looks like a half inch and dead air space is a pretty good insulator.
I have 10’ of single wall above my shop stove. It’s fun to shoot it with the IR gun.
I have 10’ of single wall above my shop stove. It’s fun to shoot it with the IR gun.
So in a 'common' situation of chimney connector pipe from top of stove to chimney pipe in a straight vertical run and 8ft ceiling hgt, a single walled pipe (24ga) is accepted to the chimney connector section that penetrates the ceiling ? If so, I imagine that temps on that connector would be down to acceptable levels after the 5ft or so of single wall from the stove top, yes ? (before starting my thread, I've gotten kinda absorbed in the other threads)
When I was planning my new install first I thought of going through the wall then straight with 20'+ of Class A but the cost of all that chimney pipe was insane so I ended up with a straight 10' shot of double wall connected to 12" of Class A. I would of went with single wall if clearances allowed it but I wanted to tuck the stove back as far into the corner as I could to save space.
Shooting an IR gun at the double wall its always under 200° at the top and maybe 300-400° at the bottom. I think this little extra heat increases the heating efficiency a bit which probably helps out with my little stove since it's pretty much maxed out as far as sq ft area is concerned. Perhaps I would of found I needed to step up to a larger stove if I decided to go with all class A? So far this stove is working fine and I had less than a cup of dry soot with annual chimney sweep.
Shooting an IR gun at the double wall its always under 200° at the top and maybe 300-400° at the bottom. I think this little extra heat increases the heating efficiency a bit which probably helps out with my little stove since it's pretty much maxed out as far as sq ft area is concerned. Perhaps I would of found I needed to step up to a larger stove if I decided to go with all class A? So far this stove is working fine and I had less than a cup of dry soot with annual chimney sweep.
Similar threads
