Woodstock pondering cleaning up old stoves with retrofit cat

[begreen]

If successful this could breathe new life into old stoves. It's been tried before with limited improvement, but Woodstock has learned a lot since early cat flue adapters came out.
http://blog.woodstove.com/2016/02/once-there-was-thought.html

 

[Babaganoosh]

Would that change the UL certification of a stove?

Edit. It's not actually retrofitting the stove, it's the stovepipe. Cats get very hot so I wonder how that affects clearance to combustibles.

 

[begreen]

No, that certification is for the stove safety and clearances. Though it does bring up the question of clearances to this device and whether 18" would be sufficient. This also does not change the pre-EPA rating of the stove. If it works it would mostly be an efficiency improvement with a benefit of cleaner emissions. Ideally the net results would be less wood burned, a cleaner flue and happier neighbors.

 

[CenterTree]

.... If it works it would mostly be an efficiency improvement with a benefit of cleaner emissions. Ideally the net results would be less wood burned, a cleaner flue and happier neighbors.

Gonna put my order in for one to give to the guy across the street who is systematically obscuring sight of most everything in the neighborhood with smoke.
Kudos to Woodstock!

 

[venator260]

This is something I'd be interested in, and I'll be watching their blog.

 

[kennyp2339]

I like how this company is trying to change the culture of wood burning from past, present and future.

 

[bushman]

Then how could you burn green wood?

 

[begreen]

You don't.

 

[bushman]

You know the oil drum stove burners will never buy this no matter what it does. Too bad they don't make this as an add on for the big dumb outdoor boilers. That's my biggest peeve, the smoky wood eating monsters that go all year.

 

[begreen]

Some fools burn trash in them too. A cat won't stand up to that.

 

[begreen]

More tech coming in this area is showing up at the Puget Sound Retrofit Technologies challenge. Looks like it has a preheater for the cat.
(broken link removed)
The challenge:
(broken link removed to http://www.pscleanair.org/priorities/woodheating/woodstoveprogram/Pages/WSChallenge.aspx)

 

[3650]

Nothing new here....Sotz had an add on cat for their barrel stove kit 30 years ago. In fact you can still buy replacement cats for them.

 

[begreen]

Yes, there have been and still are cat adapters. The preheater is new and cat tech has progressed so these might be more efficient. There are still questions in real world operation about how well they work.

 

[venator260]

I wonder how much electricity the preheaters in those types of designs would use? I wouldn't suppose that anyone here has an answer. However, if it gets to be too much, that would put off a lot of folks that would otherwise be interested.

It, of course, would come down to how much electricity it uses vs how much less wood one would use and how much they value the time they saved cutting wood.

 

[begreen]

If burning dry wood the preheater should only come on briefly to get the cat up to temp. A guess for power consumption would maybe be like running a vacuum cleaner for 10 minutes?

 

[3650]

oh missed the preheater bit....yeh that's interesting.

 

[venator260]

If burning dry wood the preheater should only come on briefly to get the cat up to temp. A guess for power consumption would maybe be like running a vacuum cleaner for 10 minutes?

I'm not sure why I didn't think about the fact that it probably only comes on as needed.

 

[vasten]

I guess I don't see how you can get more heat out of the stove if the CAT. is on the pipe, vs in the stove. any heat generated seems to go up the pipe vs back into the stove.
if you damper the stove down, to get a longer burn, and the cat kicks in to clean the emissions. But BTU wise I dont see it.

 

[venator260]

I guess I don't see how you can get more heat out of the stove if the CAT. is on the pipe, vs in the stove. any heat generated seems to go up the pipe vs back into the stove.
if you damper the stove down, to get a longer burn, and the cat kicks in to clean the emissions. But BTU wise I dont see it.

I suppose that it depends how much stove pipe one has exposed. I have about 3-4 horizontal feet between my stove and the wall. An increase in the temperature of the exiting gasses would increase this pipe temp, allowing at least some heat to transfer into the room, or at least I would think so.

 

[Slocketman]

I've thought about the pros (extra heat) & cons (lower flue gas temps > creosote) of wrapping those first few feet of pipe after the catalyst with some sort of giant passive heatsink to pull some of that extra heat out. Thinking of something like bunches of giant CPU heatsinks stuck to the pipe, but somehow wrapped around the whole thing & more elegant.

The catalyst on my insert is built right in to the damper rod and vents directly to the flue, so while I'm sure it's helping keep the overall firebox temperatures up most of that heat right after the catalyst is just going straight out. That + no type of baffle/flame impingement plate under it doesn't give the best efficiency... though I do have all that nice extra space in the firebox.

I wonder if anyone has production going of add-on secondary burn tubes for common older stove models. I've seen several nice DIY experiments and am thinking about it as a good summer project for my insert.