sray
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Posts: 11
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Post by sray on Mar 15, 2013 3:32:43 GMT -8
Greeting All; Been lurking and building, so i thought it is time to share. Here's my build so far, a 6" octagonal out of splits fire brick with full brick in an extended octagonal for the burn chamber. All to Peter's basic dimensions. Built a frame from recycled bed frames to hold brick to shape with no mortar to test burn. Riser insulated with 1" wool and covered with a scape piece of 10" ss pipe. First course of the riser is full bricks and encased in 2" perlite/clay slip in ss tin. Fire box insulated in the perlite/clay and covered with hardy board, tile to be bonded next. Fabed a steel wrap around manifold to plumb to an existing chimney (took out the old box stove). Another frame around the barrel (3" out) to hold tiles to cover the 55 gal beast (next step , to do) . Need to build a door too, going to use a glass pie dish for a window. Will post pic of the final build in a week. Steve R Attachments:
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sray
New Member
Posts: 11
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Post by sray on Mar 15, 2013 3:35:51 GMT -8
pic 2 Attachments:
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sray
New Member
Posts: 11
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Post by sray on Mar 15, 2013 3:37:05 GMT -8
pic 3 Attachments:
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sray
New Member
Posts: 11
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Post by sray on Mar 15, 2013 3:37:54 GMT -8
pic 4 Attachments:
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Post by Donkey on Mar 15, 2013 7:14:41 GMT -8
That is a nice build, well done! The only thing I can see to make it better is to add mass. There is a WHOLE lot of heat that you are not capturing with that system.. In fact, I'd say MOST of the heat that you are producing is going pretty much straight out the chimney (unless there's something I don't see on the other side of that wall).
'Course, your floor would need a lot of attention to hold up the weight and protect it from the heat. Another alternative would be a second bell, basically another 55 gallon barrel. Plenty of info on bells 'round here in case you're interested.
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Post by Vortex on Mar 15, 2013 10:39:27 GMT -8
Thanks for sharing! I'd second what Donkey said - more mass. A word of warning about using pie dish lid for window, they work great but dont try to 'fix' it into a metal door frame, it will crack. I learnt the hard way, I now have mine loosley held with aluminium foil wrapped around the edge to allow for the differential expansion and contraction of the glass and door. Also never touch the glass with anything when it is hot, the pie dish lids can take really fast heating but not cooling.
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sray
New Member
Posts: 11
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Post by sray on Mar 19, 2013 9:02:19 GMT -8
Thanks for the reply's;
I got the pie plate feature from your posts Vortex, thanks! and yes I will use a heavy gasket on the glass. This instillation replaces an old box stove, the chimney system was built to extract heat from the flue liner (6" thin wall titanium surplus Boeing salvage) which is inside a 12"square air duct the whole 2 stories high (outside of air duct is well insulated). A blower in the ceiling of the top floor forces air down the duct to channels in the 4" concrete slab floor the unit is setting on. This is my mass heat storage. Not the best as it is conduction to convection back to conduction with a powered transfer driver, but I do get good air circulation (both floors are open, ie. connected w/ stair well & balcony).
Here are some design features which may help others:
I tried to keep the mass of the firebox & riser as small as possible so the reaction time of the unit is fast ( Matt and Ernie's tips) so the firebox and lower half of the riser are one brick edgewise thick (2 1/2") and upper riser a split brick thick (1 1/4"). To get it structurally sound, the steel frame made of recycled bed frames holds the bricks in place and provides a cavity for insulation and surface for the finished tile.
The 6" octagon riser w/ 1" ceramic wool insulation (from old electric household stove) in a salvaged ss 10 1/2" dia. thin walled pipe is as small a OD-CSA as possible to maximize the drum/bell CSA ratio to system CSA (Peter's+ masons 4X min) and hence slow the flow rate of flue gas to increase conduction thru the bell.
I like the thin wall steel drum for a bell as it maximizes the heat conduction/withdrawal, and temp drop of the flue gas to boost the draft. I mounted the drum on a frame of 2" X 2" X 3/16" angle stock, cut/bent/welded to a octagon so the drum lip sets into it to create a channel between angle frame and drum that is filled with loose sand as a self repairing gas tight gasket that can easily be removed for drum replacement when it burns out ( 55 gal drum a readily replaceable recycled item).
Wrap around manifold a must (increasing CSA as it wraps around, for optimal distribution of collected bell gasses) as the slowed flue gas at the bottom of the bell must be collected and re-accelerated to the chimney, always a problem with RMH's. I did mine in steel as I needed to put it into an existing 20" high exit port, but could do in cob just as well. Clean out here of course.
Tile octagon framed 3" out from the drum/bell has slots on the bottom and open on the top to create a exterior chimney effect to sweep the bell surface, boosting convection, shields hot bell surface for safety, hides ugly 55 gal drum. (built to remove top of 3 panels to replace drum).
My 8" extended octagon firebox (side bricks 2 high w/ butting edges square instead of 22 1/2 deg. cut off corners like all the rest) is just one brick thick (2 1/2") from the 6" octagonal riser that has a missing soldier brick where it joins making a 2 1/4" X 9 !/2" throat, but I infilled it with cut off corner scraps so it is more like a nozzle. Parget coated all the interior surfaces with kiln mortar. The double ram horn, twin corkscrew vortex is VERY impressive.
Preheated P-channel secondary air from a channel down the outside of the riser to an outside air plenum that also supplies primary air just under the door. Ash box also in the square box (plenum) on the floor in front of firebox (right side in pic). Scrape ash thru air supply hole to a collection pan.
Was worried about smoke back when the door was open as the firebox roof is higher then the nozzle/tunnel top( head space), but the draft from my always heated chimney, even when starting cold, is so good that it will blow out my starter fire if I don't partially close my top chimney damper!
This whole build is made of recycled/scrape material,(I'm way big on reuse) except I bought kiln mortar (sairset 3000 F) and high temp paint.
Can supply more pics and/or detail if anyone wants. Steve R
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Post by Vortex on Mar 19, 2013 10:41:57 GMT -8
Sounds great Steve, would love to see some pics of the finished project.
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Post by blindpig on Mar 29, 2013 7:34:12 GMT -8
I agree with vortex,keep 'em coming (pictures) OK?
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Post by tat1477 on Mar 29, 2013 8:42:49 GMT -8
That looks really nice and well thought out.
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sray
New Member
Posts: 11
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Post by sray on Apr 2, 2013 6:36:03 GMT -8
here are some final pics Steve Attachments:
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sray
New Member
Posts: 11
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Post by sray on Apr 2, 2013 6:38:51 GMT -8
no 2 Attachments:
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sray
New Member
Posts: 11
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Post by sray on Apr 2, 2013 6:39:37 GMT -8
no 3 Attachments:
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sray
New Member
Posts: 11
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Post by sray on Apr 2, 2013 6:41:36 GMT -8
I guess I'm too late to enter Erica's " hide the ugly barrel contest" Attachments:
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Post by peterberg on Apr 2, 2013 6:57:41 GMT -8
I guess I'm too late to enter Erica's " hide the ugly barrel contest" Congrats, Steve! This is very nice, totally unexpected. How did you fix the pieces together? And what are the results of burning so far?
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