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Post by patamos on Feb 17, 2020 10:35:07 GMT -8
Trev, do you know about the chopping in a car tire trick? Pack the sticks (vertically) pretty tight, and whack away at them...
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Post by patamos on Feb 7, 2020 17:40:26 GMT -8
Hey Pat, Good to hear from you Are you running the same stove setup this winter? What do you use for tinder? I had a load of wood shavings which were brilliant but I've run out now. When lighting from on top with paper and cardboard it seems to smother the kindling in a thick layer of ash. I think traditional tinder was dried moss, we have tons of that here but I've never tried it. Ya, same triple shoe box with inverse aryan. I took out the sloping firebox roof and replaced with a corbelled brick and CFB lay up. Presently have bottom air feed spanning the width of the last (deeper) third of the firebox floor. I got into burning top down after a few good exchanges with Norbert over at MHA, whose Condar PM analyzer has been indicating much the same improvements with that kind of burn strategy as your testo has. For tinder and fine kindling i use a stash of shredded scotch broom. Last summer i built a light clay cabin using that as the fibre. My neighbour runs a business clearing it from the land under hydro lines. Brought me 4 yards of chipped broom which i then ran through a 5hp shredder. Then sifted through 1/2" screen to get the size i needed for mixing with clay. The bigger stuff that wouldn't get through the screen (about 5% of total) has made awesome tinder. Kind of like twigs coated in lighter fluid
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Post by patamos on Feb 1, 2020 13:28:47 GMT -8
Nice work Trev Great to see your graphs/numbers so dialed in. This adds to a growing body of evidence for a tightly loaded top down burn with side air intake - at least in relatively large firebox configurations. Interesting to see the effects of closing bypass well into the ramp up phase. This has convinced me to open my bypass only 10% or so for a few minutes on start up. With a good nest of tinder and kindling the burn is clean from the get go...
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Post by patamos on Sept 25, 2019 14:52:46 GMT -8
adding extra height to a barrel/bell tower is not a problem, although i'd be inclined to add a bit more length to the heat riser as well. somewhere in the mix the definition between a bell chamber and downdraft chamber gets blurry, as free stratification of gasses involves a relatively non-turbulent environment. Adding height to the riser makes it behave more like a downdraft or 'contraflow' harvesting system.
my 2 c
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Post by patamos on Aug 3, 2019 9:44:57 GMT -8
And in case it has not already been mentioned: You can always fire a smaller heater more often or do multiple reloads. For cooking purposes it is nice to size the fire chamber smaller, and arrange the longer flywheel harvest to absorb twice daily firings... etc...
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Post by patamos on Jul 15, 2019 8:21:27 GMT -8
Ya, I am intereste in hearing more about the water cooled heat exchanger you are working on.
Ive experimented with blower fans on oversized harvesting mass. Trouble was the rate of draft was not always optimal for the variable rates of combustion in a given burn cycle; at times making for too much residency, other times not enough. Co2 is heavier than ambient air, so at equal temperatures the exhaust gasses will want to descend. But this force may not always be enough to pull the gasses through a system oversized enough to harvest all that heat. Seems it would make more sense in a gymse or RMH where the push through the heat riser is strong and the burn rate is somewhat gradual.
ONe idea (for my above-mentioned build with only 4' drop) is to have both an ascending flue with the usual optimized harvesting system, and also a T junction with a longer run through an added harvesting element (water jacket, or extended earthen mass...) powered by an fan/pump that is tuned down to draw only some of the gasses.
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Post by patamos on Jul 14, 2019 17:56:40 GMT -8
Condensing flueas are once again in my mind, so thought i'd revive this thread. A quick google search brought up all kinds of examples at a macro scale. dallenergy.com/en_gb/biomass-technologies/flue-gas-condensation/I'm getting ready to build a heater for friends that has a steep drop off behind the house. So a purely gravity powered operation is in the cards... The build after that has only a 4' drop to surrounding ground level. BUt i wonder if a super efficient water jacket - more like a reverse boiler - could do the trick
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Post by patamos on Jul 14, 2019 17:28:16 GMT -8
Ya that makes sense. But i am referring to the drag on the flow of gasses through the system caused by pulling hot gasses downwards when they naturally want to rise upwards. It may not be a major factor. Just wondering if anyone has info on this
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Post by patamos on Jul 14, 2019 10:13:39 GMT -8
I wonder how much less 'push' the downdraft systems have? I know Matt's side drafting split riser set up benefits from a little more buoyancy in the exhaust flue to pull the gasses through a given harvesting mass.
Not to dis down-drafters, maybe they are great in this respect. But my guess is some extra resistance is involved. In all the discussion of combustion efficiency we often forget that in real world firing, optimal harvesting is no less important.
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Post by patamos on Jul 7, 2019 19:18:43 GMT -8
Ya, gravity cap vented is the way to go. nothing intricate to malfunction - and intricate valves will eventually malfunction. SOme masonry heater builders put big 1.5" or greater tubes into the harvesting mass wall of a bell or flue run body. Slow ramp up. Risk of flash way low. The sheer volume in the tubing also offers some storage capacity for showers and such....
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Post by patamos on Jul 7, 2019 11:23:27 GMT -8
Hi Minervalong. From the sounds of it, you might find value in spending some time in the reference library. The amount of info on this site can be daunting at first, but gradually the common principles come clear. Beyond that, the folks on this forum are most willing to help you out.
There is an old permaculture saying: better to do protracted and thoughtful observation rather than protracted and thoughtless labour.
One important piece of design/build I'll mention here is: anywhere you are transitioning, turning a corner in the gas path, you had best open the cross-sectional area (CSA) of the channel to at least 150%. This will reduce turbulence and eliminate constriction. Also, if you bell entrance port is at the same end of the bench as your exit port into chimney... heat distribution to the far end might not be very good. Better to run a flue within the bell (even just a 6" steel pipe) to the far end and then let the gasses work their way back to the exit.
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Post by patamos on Jul 5, 2019 8:33:09 GMT -8
lower temps with lower flow rate will give adequate residency time for thermal transfer. It will be a slower response time, but if you are okay with that kind of longer flywheel then should be no problem
my 2c
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Post by patamos on Jul 2, 2019 8:50:53 GMT -8
So editing in a little bit of context, My client-who-has-become-good-friend and I have a good laugh from time to time. Mostly dreaming of posting up some 'comical how-to ham-up... But this was our first serious attempt as an instructional video.
If any one is the least bit offended... let me know and we'll yank it
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Post by patamos on Jun 28, 2019 19:00:39 GMT -8
Hi Bram, This heats 450 sq.ft dwelling in west coast Canada temperate rain forest. Easily on one batch, When below zero c one more reload will keep things warm for 12 + hours vimeo.com/334174847?cjevent=e73b83aa9a1811e983ce012c0a1c0e0fIf you shape the outer shell of the fire chamber and down draft roughly 24 x 32 you can sit a stove glass top on it and have whatever core and side/downdraft chamber(s) you like. To get to the far end of a bench i'd suggest a relatively fasts channel along the front (into the room), then a slower bell coming back towards the flue. This will help even the temps out. Also, any major bend in the 90 degree range, good to widen the CSA by 50%... With a bypass you can waaaay over size the ISA, but good also to have cleanout ports into which you can place bricks or w.h.y. on the floor or side walls to reduce the volume and speed things up.
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Post by patamos on Jun 25, 2019 21:24:53 GMT -8
Ditto on the faith in ceramic glass tops. You'd have to whack one pretty hard with a heavy pot to crack it. Think of all the abuse those things take in the average home over many years. They have to pass some pretty stringent standards to be used in that major an application. They also radiate less than equal thickness cast iron. But they conduct better. The Ma n'Pa appliance centre in my town is happy that scavenge them from oven/stoves otherwise heading for the waste stream.
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