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No roar
Oct 21, 2014 23:08:19 GMT -8
Post by freelsd on Oct 21, 2014 23:08:19 GMT -8
Greetings to all the decent community. I've built my first ever stove, intended to be bell rocket, simpliest setup as I thought, but in practice it won't enter rocket mode. Heat riser is thick walled ex-flue pipe 120mm / 4.7" dia, 78cm / 30" tall. Insulated with perlite. Burn tunnel is 240mm / 9.44" long, entirely made of refractory brick. The top of bell is covered with cast-iron plate - ran out of pictures here. Exhaust is also 120mm pipe, guided out horizontally under yurt floor. Feed tube is assembled each time with brick, after cleaning the burn tunnel of coals. The complication I've met is that even after a long burn it won't roar. Exhaust gases are of white color and smoky, as of regular campfire. Moreover, the ash pit seen on picture is full of glowing coals after ten minutes of burn, so coals begin to enter the burn tunnel as sticks are added to maintain the burn. May that be due to the lack of insulation around ash pit and whole the feed tube? Or it's the heat riser can't get to temperature due to thin layer of soat it's covered inside , as it served as ordinary flue before?
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No roar
Oct 22, 2014 1:04:11 GMT -8
Post by Dan (Upstate NY, USA) on Oct 22, 2014 1:04:11 GMT -8
Your horizontal burn tunnel looks smaller than your heat riser. I never saw an 4" - 5" system that worked, just heard about them...
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No roar
Oct 22, 2014 2:53:06 GMT -8
Post by freelsd on Oct 22, 2014 2:53:06 GMT -8
Thank you for suggestion. It's actually is 11.5x7 centimeters, which gives 80.5cm^2 CSA, against 113cm^2 of heat riser.
Also to mention, sometimes burn begins to oscillate at a rate of approximately one hertz, like willing to change the direction, but it doesn't - just 'poofs' in feed tube at a stable frequency. Playing with primary air amount and sticks arrangement takes it to stop.
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Post by satamax on Oct 22, 2014 8:37:15 GMT -8
Thank you for suggestion. It's actually is 11.5x7 centimeters, which gives 80.5cm^2 CSA, against 113cm^2 of heat riser. Also to mention, sometimes burn begins to oscillate at a rate of approximately one hertz, like willing to change the direction, but it doesn't - just 'poofs' in feed tube at a stable frequency. Playing with primary air amount and sticks arrangement takes it to stop. Way too small. Maximum reduction a burn tunel can whistand, is 5% reduction compared to the feed and heat riser. Plus, i bet your 11.5 is the width and 7cm the height? If yes, that's even worse, because low and wide burn tunels are known for being problematic. 4 inch systems are a pain too. So get back to the drawing board mate! Plus, horizontal flues without a vertical chimney are worth fuck all!
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Post by matthewwalker on Oct 22, 2014 8:58:49 GMT -8
I'll just add that there is way too much mass around the entire burn zone, which is why you have coaling like you do. The smaller the heater, the more important low mass, insulated combustion zones become.
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No roar
Oct 23, 2014 2:09:21 GMT -8
Post by freelsd on Oct 23, 2014 2:09:21 GMT -8
Thank you, gentlemen. I see now that smaller the unit the more protection flame needs, to get the idea to work. I hope to correct things without dismantling the whole brickwork, as it gets too cold to restore it.
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No roar
Oct 23, 2014 3:10:39 GMT -8
Post by photoman290 on Oct 23, 2014 3:10:39 GMT -8
i also am trying to design a RMH for a yurt. i am going down the batch box route rather than the j tube. first experiments are looking good. still need to buy/find some metal for the p channel. the biggest problem i am finding is getting enough clearance between the top of the stove and the roof of the yurt. still working on that one. your yurt looks about the same height. mine is around 5 foot 10 inches. i have just raised the part of the roof where the stove will go to 68 inches. i do know at least one person has put a RMH in a yurt succesfully. they had the fire box outside with a long burn tunnel. have a go at a batch box. the dimensions are very precise but that is a great help in my opinion.
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No roar
Oct 23, 2014 6:31:59 GMT -8
Post by Donkey on Oct 23, 2014 6:31:59 GMT -8
Welcome to the boards, freelsd! Please, be gentle on the attachments.. I just cleared some space in the boards attachment folder, it was totally full and not accepting new attachments just yesterday! If you plan to post a lot of images (gonna stick around?) it would be BEST if you use a 3rd party image host that allows linking out. Images for viewing on screen don't need to be any larger than 600 pixels along the long edge. Also there are people here with very poor internet connections and big images are no fun for them (myself included).
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Post by freelsd on Oct 23, 2014 8:11:55 GMT -8
Mine khana is 4 foot 7 inches tall. The bell is about the same height. Donkey I beg pardon! Always in hope on some automated processing. I promise you to look after myself in future.
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JJ
Junior Member
Posts: 56
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Post by JJ on Oct 23, 2014 8:22:47 GMT -8
Mine khana is 4 foot 7 inches tall. The bell is about the same height. Donkey I beg pardon! Always in hope on some automated processing. I promise you to look after myself in future. Tinypic.com is a good free picture upload source. I always use facebook - copy URL and use that URL to post it here via 3rd party.
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Post by thickstrings on Oct 24, 2014 6:36:17 GMT -8
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No roar
Oct 24, 2014 22:03:53 GMT -8
Post by freelsd on Oct 24, 2014 22:03:53 GMT -8
Thank you for sharing. You offer a good solution, as I definitely felt the lack of radiant heat the barrel could produce. Could you please highlight a bit the details of your construction? Is there T-tube placed with it's long side horizontally, with an elbow attached as transition to heat riser? Isn't there any ash pit?
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Post by thickstrings on Oct 25, 2014 0:54:12 GMT -8
Yes, It is a sacrificial 4" H Vac Tee, with a elbow to make the transition to the riser. I used a insulating castable mix for the core, as suggested above by Matt. It sits on 2" of ceramic board and the sides are a mixture of mud, perlite and fire place cement. Over the top of the whole thing is Fire brick cement and sand. The manifold area is fashioned from firebrick splits and covered with the firebrick cement and sand mix to achieve the rounded sides...Riser tube is a 4" H Vac inside a 8" filled with a perlite and fireplace cement mix...Riser is 20" The barrel is 14" x 22" So, a 2" top gap and 3 1/2" sides. The box is just some Ikea detris but it sure could be made permanent. I have fashioned a clean out in the front, the cap is filled with 2" of ceramic fiber board. There is a 4" elbow near the bottom of the manifold that goes to the 4" exhaust pipe. I have had the barrel top to 650f, but, it will generally run in the high 4's to 500f range with just 10' of exhaust pipe. I could not measure the exhaust gas temp with my laser, but, the end of the pipe at 10' was 110f. I suppose it would heat a small bench of 5' or so...a bell?
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