Wood Stove Decathlon

[matt walker]

I just posted this over at Donkey's board, but wanted to put it up here for those of your that are interested in the nuts and bolts of the thing. Here's what I wrote over there:

"Finally home, 7100 miles on the odometer for this trip! I'm tired.

Those box stoves were very impressive, and I'd be delighted if all of my neighbors chose those stoves. They were amazingly clean, no visible smoke, exceptional numbers on the testing machines, and they threw out a ton of heat. I still think that a constant burn is going to be far dirtier than our short burn/long heat cycle heaters, but they are really something and gave me a lot of hope, truly.


As Sandy mentioned, our heaters are probably not ever going to do very well in the particulate measurements of the small particles. We just have too much turbulence and a lot of air moving through the ash bed. The particles we are concerned about are inorganic, so cannot be burned out, and are so small and light that once they are in the gas flow they act like gas. Short of an electrostatic filter or a physical filter, we are probably going to have high particulate emissions, which is kind of a bummer. To be fair, my heater had no secondary mass or chambers, which surely would reduce particulate somewhat. Also, again, the short burn/long heat cycle goes a long way to mitigate this, so overall I'd say we are still right down there with the best of them in real world applications.

The testing followed either the EPA test method 28 or the Masonry Heater ASTM testing method. In the former the box stoves were tested after 30 minutes of loading a warm stove, for 15 minutes. Using the latter the masonry heaters were tested 15 minutes after lighting from cold.

Neither was appropriate for testing a rocket stove. I tried to get them to change but things were hectic and I may have been a bit too passive, however they were very gracious and I never felt that things were unfair on purpose. We all learned a lot about how these burn and how we might set up a testing protocol specifically for these devices. Obviously, after 15 minutes the fuel load is on the downhill run, and the machine didn't actually get numbers until 3 minutes after official start, so 17 minutes into a burn. Not only that, but a 15 minute "snapshot" of our burn cycle is like 80% of the total burn, where as with the box stoves it is truly a snapshot of a 6 hour burn.

On Monday, I did succeed in getting the head testing judge and one other judge to oversee an unofficial run, with the first numbers coming at 6 minutes after loading. That run had CO running from under 10ppm and occasional drops to 0ppm over the following 10 minutes before coaling stage started and CO started to rise. My 02 levels were high (10%) since I gave it plenty of air to allow for the tall stack and no load (mass) on the stove. Likewise exhaust temps were high which hurt the efficiency calculations. The judging pool was so very experienced, they all understood all of those factors better than I, and were overall impressed with our technology.

Like I said, we did a whole lot of good at the event. Had some great conversations with the actual individuals who are the regulators, decision makers, test protocol writers, and so on. Sandy and I together did some ground work on the path to getting through the maze of regulation and I think there is a clear path to getting these devices recognized as safe and legal to install. It's going to take a lot of work and quite a bit of investment, but the path is there.

As for the event overall, man, I gotta say, it made me very optimistic about wood heat in general. Pretty much all of the entries were impressive, and I learned that there are other very clean burning heaters out there for folks to choose from. Conversely, the wood stove world has now had first hand experience with a decent rocket stove, and I think as a whole we made a good impression on the industry and regulation folks."


And, as an aside for you all, my friends, I'd like to elaborate a bit on the part of the trip that was not the wood stove challenge. I had the opportunity to get to know and have some quality time with some decision makers in DC with regards to stuff we care about. Water, fracking, wildlands and wilderness, air quality, Big Ag and practices, and so on. I don't do politics, and never have, but I gotta say, without exception every one I met there who is working on this stuff was amazing. They were informed, and truly caring. I was really inspired and have a ton of hope and optimism for the future. Those were exactly the people I'd like to be making decisions about the things that matter to me. They would all fit right in here with us.

[Lollykoko]

Matt, I'm glad to hear that the trip was enjoyable. Thanks for taking time to talk with influential folks about the very important environmental issues the nation faces.

[mannytheseacow]

It sounds like a good experience you had, Matt. I'm curious about your views looking ahead and how to apply the different technologies that you were exposed to there. If some of these other heaters are cleaner burning, they could still be coupled to a mass and work similarly to RMH design, right? It seems like heater designs are pretty specific to regional climates as well as home design in regards to effective application. Did you see anything that burned clean enough to couple to a mass but had a large firebox that could burn for hours and hours without the attention and constant feeding that RMHs require?

[matt walker]

It's a good question Manny, and the answer is no, and I still think our heaters are the best solution for DIY folks. I learned a lot about masonry heaters at the event since I spent quite a bit of time hanging out with Richard Jussel who built the kachelofen and also with Rod who has built many, many beautiful masonry heaters. I didn't realize that they NEVER load on coals, so it's start from cold, burn for 40 minutes, then close the air and wait hours before they will load again. That's because the coals will smolder the bottom of the fuel load and the heaters will burn dirty, which will eventually creosote up the flues. In my opinion the lack of the quick radiator makes that cycle not as appealing to me. In a tight house like yours, it may work just fine, but you'll never get that hot "I'm having a fire" feeling like we do. They were beautiful though, and if you got your cycle down, well, the house would never be cold, so one or two fires a day might be a welcome respite, depending on your schedule.

As for the rest, still box stoves, even though they were amazing. Try to cool off the exhaust any more than the designers planned and they won't work at all, so no heating mass with those. They were great heaters though, and would use a fraction of the wood we are used to from our old metal boxes, with the same type of heat cycle and output. I would consider one if I could afford the stove + chimney, which even for the cheapest one would have you up above $3000 pretty quickly.

As for amazing technology, or eye opening stuff, I think ours were the real highlight. Jason's insert for a normal box stove was truly amazing, and it did make the old beast totally smokeless. It was throwing off a TON of heat too, actually, too much, it was incredibly hot. The downside I saw there was that exhaust temps were ridiculously high in normal use, so not only was a lot of heat lost, I'd worry about putting one in my place until I reconfigured the chimney. It still might be a great option for a cheap retro fit to clean up a neighborhood, but again, not something we can use to improve our burners. Actually, his thing just makes a wood stove into a sort of rocket, with the chimney as the riser. He's considering coming to stay with me in the coming week, and I'd like to try to help him get a radiator on top of a box stove to keep some of the heat inside.

Otherwise, as for amazing technology, or eye opening stuff, I think ours were the real highlight. The other stuff was electronic automation, fans, the Kimberly, and the Wittus, with the downdraft gases flaming in a window. That thing was cool as all get out and threw out a ton of heat, but again, we are already doing basically the same thing with mud and barrels. It just doesn't look as cool. Nothing I saw could be applied to mass, that I could figure.

The winners, Woodstock Soapstone, bought my stove and took it back to their lab to play with. The head judge from DOE's Brookhaven Labs expressed interest in getting one to test and play with as well. Woodstock has plans to see if there's something here they can use, and I intend to help them get to know the technology as best I can from here. Overall, even though I totally lost, I think the RMH was a big, huge win at the event.

[DevilsBrew]

[rjdudley]

Matt, I want to say congrats on the stove demo! It seems as though you accomplished most of your goals AND exposed the RMH to some brilliant minds. Hopefully some great progress can be made.