Shop Heater Pellet Stove Heat Reclaimer Idea...

[tallfarmboy]

Ok, I've been reading in this forum for a long time, but never have registered until today. Some of y'all are thinking, oh no, here we go again... another heat reclaimer idea... LOL! Well, hear me out....

I've got a 30x60x10 shop that is barely insulated (bubble wrap)... I've got 2 pellet stoves that I light up whenever I want to be in the shop and they both work fine. However, I would like to be able to get my shop warmer than I am able to get it now by reclaiming some of the heat that I lose in the exhaust. My current setup is a single 3.5" hole drilled in the tin exterior with a single 12" piece of double insulated flue pipe exiting from each pellet stove. Very simple. My idea is to slide each of the pellet stoves over and put a single 55 gallon drum in their place. Then, cut 2 different 3.5" holes in the drum, one for intake of the exhaust from my pellet stove, and one for exhaust to the outdoors. The 55 gallon drum becomes a large surface area heat exchanger that should become pretty warm, in my opinion.... This setup would be extremely easy to clean and would only require me to purchase a 90 degree elbow and another piece of flue pipe for each of my stoves.
Will this idea work? I am looking for any and all ideas and or criticism.

Cheers!

TFB

 

[Ssyko]

Im an experimental type so try it and see! Only thing that I wouldn’t want the footprint. Floor space in my shop is at a premium

 

[SciGuy]

Ok, I've been reading in this forum for a long time, but never have registered until today. Some of y'all are thinking, oh no, here we go again... another heat reclaimer idea... LOL! Well, hear me out....

I've got a 30x60x10 shop that is barely insulated (bubble wrap)... I've got 2 pellet stoves that I light up whenever I want to be in the shop and they both work fine. However, I would like to be able to get my shop warmer than I am able to get it now by reclaiming some of the heat that I lose in the exhaust. My current setup is a single 3.5" hole drilled in the tin exterior with a single 12" piece of double insulated flue pipe exiting from each pellet stove. Very simple. My idea is to slide each of the pellet stoves over and put a single 55 gallon drum in their place. Then, cut 2 different 3.5" holes in the drum, one for intake of the exhaust from my pellet stove, and one for exhaust to the outdoors. The 55 gallon drum becomes a large surface area heat exchanger that should become pretty warm, in my opinion.... This setup would be extremely easy to clean and would only require me to purchase a 90 degree elbow and another piece of flue pipe for each of my stoves.
Will this idea work? I am looking for any and all ideas and or criticism.

Cheers!

TFB

My best guess is that if you extract too much heat from the exhaust stream you'll get a good lesson in how much water is created as a result of the combustion process and end up with a gloppy creosote mess in the 55 gallon drum. Condensing gas boiler's heat exchangers are constructed of high grade stainless steel in order to deal with the acidic condensate.

 

[Washed-Up]

I think it’ll work to a degree, do you have a rough sketch of the setup?

 

[SidecarFlip]

Personally, I think you'll wind up with a sticky, gooey mess in the bottom of the barrel. Once you decrease the flue gas below the condensing point, it will precipitate out the moisture and drop the ash and creosote.
Like I tell people, build it, first article test it and then report back, pro or con.

Why high efficiency NG and propane fired furnaces have condensate traps and extraction fans to move the condensate from the cold side of the HX to a floor drain.... and the condensate is acidic but clean whereas yours will be nasty dirty with fly ash and other particulates.

Guess you could install a bulkhead fitting and WOG valve on the bottom of the drun to drain it off and dump it in the dirt somewhere...

 

[SciGuy]

Personally, I think you'll wind up with a sticky, gooey mess in the bottom of the barrel. Once you decrease the flue gas below the condensing point, it will precipitate out the moisture and drop the ash and creosote.
Like I tell people, build it, first article test it and then report back, pro or con.

Agreed..........Combusting 1lb of bone dry wood creates ~ 1/2lb of water that normally follows the nice warm flue gasses out the vent. If cooled to the dew point as you say they will condense out.

 

[SidecarFlip]

I think what you really need is a double barrel drum heater like the Vogelzang. Your minimal insulation won't be an issue then......

Im an experimental type so try it and see! Only thing that I wouldn’t want the footprint. Floor space in my shop is at a premium

So am I. Was my primary reason why I bought the stove I bought 20+ years ago. Only unit I've ever seen that is almost infinitely adjustable via the keypad to change every parameter of how it operates. The only non adjustable set point is the convection fan on temp. Every other algorithm is user programmable. Probably why the control boards are so expensive too. When USSC went from the 2 button board to the 4 button digital readout, they hit it out of the ballpark. Only downside is they won't allude to how to custom set it but that was addressed a long time ago and that information is now readily available and in the WIKI.......

 

[tallfarmboy]

I appreciate all of your feedback. I am absolutely aware of the condensation and creosote mess possibility, but I believe that the mess will be contained and hopefully easy to clean up in the barrel. It's too dang cold to do much, but I'll definitely update y'all if I decide to act on this.

 

[tlc1976]

Besides the condensate, I think the cooling and added turbulence will reduce exhaust efficiency. Possibly negating any gains of drawing waste heat from the exhaust. Would be interesting to see what your findings are.