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Post by stephenson1 on Dec 29, 2013 11:20:07 GMT -8
Hi everyone and thanks for all the informational resources. I just finished the basics of an RMH backup heater and it seems to function well. Next step will be lime plaster and cob I guess. Special thanks to Ringoism and Chrisburge. Your work in particular inspired this. www.youtube.com/watch?v=FUqjQu6-i4A |
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Post by ringoism on Dec 30, 2013 8:26:16 GMT -8
I watched the video and your project looks really great. I really like your use of the cinder blocks for mass, and would consider doing the same if I could find them here! I didn't catch any mention of "system size" (feed/tunnel/riser dimensions) - what is it? And your drum is only 27" high? I'm wondering how much lower I could go with my drum and still have it draw well enough. Glad my own little project served as one source of inspiration, and thanks for the credit.
-Eric
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Post by matthewwalker on Dec 30, 2013 9:32:03 GMT -8
That is a fantastic build Stephenson! I love the way the cinder blocks came together and formed the channels. You put a lot of newer concepts to work in that heater and it seems to work very well indeed. Excellent video as well, thank you for sharing that.
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Post by Vortex on Dec 30, 2013 10:36:10 GMT -8
Nice stove! I thought about using the cavity blocks as they call them here, but was unsure of how well they'd stand up to the heat in my stove, they're perfect for a bench though, surprised no one else hasn't used them before - well done.
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Post by colinsaengdara on Dec 30, 2013 10:40:17 GMT -8
Very nicely done Stephenson! It's always nice to have extra heat leftover after building your thermal mass! Especially with a small system. You can always make your cob thicker to absorb more heat and protect your buns!
You said you plan to use lime plaster for the cinder blocked section, and cob for the stove section. Can you tell me a little about your thought process? Finishing is definitely my weak point. Thanks!
-Colin
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Post by stephenson1 on Jan 1, 2014 7:18:43 GMT -8
Thanks for the positive response guys. Eric, you are most welcome. I'm attaching some (sorry 'bout the quality) screenshots from a video clip that may clarify some details. Feed is 4" x 4 1/8" and drops slightly below the burn tunnel floor because I left a gap between thin fire bricks as a rest for a metal grate. I can replace the grate as it deteriorates by reaching into the ash collection space below. I also used chrisburge's wedge at the entrance to the burn tunnel which reduces the height at that point and effectively lowers the feed chamber floor as well. My wedge is 7/8" tall. After the entrance wedge, the burn tunnel is defined by the dimension of the fire bricks I used so it's about 4 1/8" square. Opening to heat riser is 4 1/2" x 4 1/8". The Kaowool riser is 24" tall and rests at the same level as the top of the feed so the height from bottom of burn tunnel to top of riser is approx. 30". . Distance between the feed and riser at the top of the burn tunnel is 6 1/2". The "atrium" where all the hot air comes together before entering the cinder block tunnels is as large as I could possibly make it and is more than twice the area of the feed C.S.A. I don't think this build gets near as hot as you described yours, and I have about 30' of chimney rising up through my house. I guess it depends on your needs. My sense is that the chimney helps with avoiding smokeback by providing continual gentle draw even at stone cold, but that heat riser height drives a vigorous burn. Maybe that's because the mass takes up so much heat that the chimney never really gets very hot. BTW, I love seeing your photos. What a view to wake up to! It's my pleasure Mathew. I've learned an awful lot from you over the past year or so as well. BTW, good luck with Walker Stoves! Colinsaengdara, as far as materials for finishing, I'm the wrong guy to ask. It's freezing in Connecticut. My sons and I ended up grabbing all of the old buckets of slop and powder from other experiments and piling them onto a tarp in my basement to thaw. We then mixed it all and called it "Cob". I happened to have a fair amount of slaked lime frozen out there as well so I mixed it up with some sand my sons sifted out of our crawlspace to make a lime plaster. I'm just winging it, but if I figure out anything useful I'll be sure to share. Cheers, Mark |
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Post by doggy1969bc on Jan 1, 2014 19:02:41 GMT -8
I did not see any cleanouts exept from the ashpit ,maiby i overlooked them ?
btw nice build ,great use of the cinder blocks ,
regards , Karl
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Post by stephenson1 on Jan 2, 2014 6:45:35 GMT -8
You're right Karl, no easy cleanout after the burn chamber.
This is intended as an emergency heat source so I expect ash build up will be minimal. My two options down the road will be to remove the barrel, the base of which I'm leaving exposed so that I can rock it to break the furnace cement seal, or to remove one or both of the concrete paver caps where the first level of duct rises to the second, and snake in a vacuum hose.
Mark
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Post by pinhead on Jan 3, 2014 10:30:08 GMT -8
I like your heat riser. I don't suspect the wire holding it all together will have any trouble lasting; once the gasses leave the riser the temperature has dropped substantially and will no longer be a threat to the wire. In fact, I have a steel sleeve inside the top third of my heat riser (in a 6" batch box) and after better than a year of burning, it doesn't seem to be going anywhere.
I like your riser much better than my ham-fisted method of clay/perlite/ash. Can you tell me where you got your hardener and Kaowool?
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Post by icarus on Jan 4, 2014 12:54:57 GMT -8
This is truly inspiring, Mark. I hope people explore the limits of this method. If you have any pics or diagrams of your feed tube please share them. I'm fuzzy on how to incorporate the secondary air and the ash removal.
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radek
Junior Member
Posts: 94
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Post by radek on Jan 6, 2014 3:13:30 GMT -8
hi Mark,this is one sweet build,thanks for sharing a lots of new ideas,i really like the idea for cinder blocks bench,awesome.
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Post by stephenson1 on Jan 6, 2014 5:16:12 GMT -8
That's good to hear about the steel Pinhead.
I got both Kaowool and ridgidiser on ebay. Ridgidiser cost about $30. for a quart. Kaowool worked out to about 37 cents an inch but I had to buy a 25 foot length. I've made several risers using clay/perlite/vermiculite, and I'll never spend that kind of time and materials for that purpose again.
I'll see if I have some more detailed shots and post them Icarus. I'm not so sure about my air supply through ash chamber idea yet, but I'll update. Radek's idea of air off the side of the feed barrel looks perhaps more reliable but I'm not looking forward to trying to cut a neat round hole into the stainless pot I'm using!
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Post by bernardbon on Jan 6, 2014 5:57:31 GMT -8
I like your heat riser. I don't suspect the wire holding it all together will have any trouble lasting; once the gasses leave the riser the temperature has dropped substantially and will no longer be a threat to the wire. In fact, I have a steel sleeve inside the top third of my heat riser (in a 6" batch box) and after better than a year of burning, it doesn't seem to be going anywhere. I like your riser much better than my ham-fisted method of clay/perlite/ash. Can you tell me where you got your hardener and Kaowool? The principle could be that? With a suitable steel and insulation www.le-comptoir-du-poele-a-bois.fr/300-1548/coquille-isolante-plafond-poujoulat-inox-galva.jpg |
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Post by pinhead on Jan 6, 2014 9:06:20 GMT -8
I like your heat riser. I don't suspect the wire holding it all together will have any trouble lasting; once the gasses leave the riser the temperature has dropped substantially and will no longer be a threat to the wire. In fact, I have a steel sleeve inside the top third of my heat riser (in a 6" batch box) and after better than a year of burning, it doesn't seem to be going anywhere. I like your riser much better than my ham-fisted method of clay/perlite/ash. Can you tell me where you got your hardener and Kaowool? The principle could be that? With a suitable steel and insulation www.le-comptoir-du-poele-a-bois.fr/300-1548/coquille-isolante-plafond-poujoulat-inox-galva.jpgJust for the sake of full disclosure, I want to reiterate that in my stove, the inner steel sleeve is in the top third of the riser - away from any appreciable flame. Steel will definitely NOT last in the bottom 2/ 3 of the riser, the tunnel of the rocket stove, or the throat of the Batch Box rocket. The image that you linked to would work beautifully, assuming the insulation can withstand direct flame and the elevated temperatures which exist inside the riser of a rocket stove. |
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Post by satamax on Jan 6, 2014 9:12:05 GMT -8
Which it does not, being rockwool. It doesn't melt with high temp, but the binder in between the fibers fails when heated.
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