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Post by photoman290 on Oct 20, 2014 14:21:56 GMT -8
after a quick play with the batch box idea i think i may try to use it in the yurt. the problem i have is headroom. if i use a oil drum the top of the drum will get too hot. and it is going to be too close to the roof. was wondering what the restrictions on height of a bell would be.if i go for a 100mm riser and have the combustion chamber at floor height that gives me around 1 metre to the roof. that is plenty depending on how much clearance i need between the top of the riser and the roof of the bell. thinking of donkeys adobe brick experiment. i tend to be around during the day and out in the evening so storing heat in the early evening is the aim. for fast heat i can always use the oven. does use expensive gas doing that though.
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morticcio
Full Member
"The problem with internet quotes is that you can't always depend on their accuracy" - Aristotle
Posts: 371
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Post by morticcio on Oct 20, 2014 21:12:59 GMT -8
If I remember correctly, for a 6" (150mm) system Peter recommends 12" (30cm) clearance between top of riser and the roof of the bell. 8" or even 6" (200mm/150mm) should be enough for your 100mm system.
Insulate the top of the bell/drum with insulating firebrick and/or ceramic blanket. If the temperatures near the roof are still too high you may need additional protection draped in front of the yurt lining. This could be a steel sheet backed with insulation, e.g. ceramic blanket or vermiculite board, to reflect the heat downwards. Remember to leave an air gap between this and the lining.
The top of a brick bell gets hot enough to ignite wood - I had moved some of the insulated fire brick on the top of my bell and left some 3" chunks of hardwood to dry out on the bare brick - after an hour it ignited the area in contact with the brick and started smouldering. As a comparison the top of the IFB was warm to touch.
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Post by Dan (Upstate NY, USA) on Oct 21, 2014 1:06:17 GMT -8
The height of the barrel is not what is important but the height of the internal chimney or heat riser inside. The taller that internal well insulated chimney the better you stove will suck and push air. So it doesn't matter if you use a barrel or a bell you still need a high enough internal chimney to make it all work.
I had a similar problem in my living room, so I cut out the floor, built a concrete foundation up to it and started the stove right on the floor, and then made my internal chimney as high as I could so I could still get my 55 gallon drum over the chimney and clear the ceiling.
And it keeps me so warm for less than 500$ a heating season in firewood. Most people around here spend 300-600$ a month to heat their homes in the heating season.
You answer might be to dig into the soil and bury your stove a bit, just thinking...
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Post by mwalimu on Oct 21, 2014 3:31:22 GMT -8
The bigger the space between the end of the riser The bigger the volume of the bell, The longer the riser The better the insulation of the riser
- The better is is the gas speed / push trough the system, so you can play with these factors if you need the push.
Heat storage is better with a bell
But water has four or five times the storage ability of adobe/brick per weight, so a drum with a water jacket would do this - and you have no problem with overheating your ceiling.
If you chose a bell or drum, something like a stone / concrete plate with some spacer between (for air convection) on top of it will surly protect from overheating the ceiling and store additional heat. With this configuration and a drum you would have quick heating plus storage.
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Post by DCish on Oct 21, 2014 18:44:12 GMT -8
water has four or five times the storage ability of adobe/brick per weight, Yes, but as I am fond of crediting donkey with pointing out, this is only applicable until the phase change temperature of water is reached. Then water wants to escape (even more than usual!). Adobe can store more per unit of mass in the practical sense because it can continue to accept heat long after the point of phase change of water. And it doesn't try to run away, or breed nasty bacteria, or explode, or...
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Post by mwalimu on Oct 22, 2014 2:13:15 GMT -8
water has four or five times the storage ability of adobe/brick per weight, Yes, but as I am fond of crediting donkey with pointing out, this is only applicable until the phase change temperature of water is reached. Then water wants to escape (even more than usual!). Adobe can store more per unit of mass in the practical sense because it can continue to accept heat long after the point of phase change of water. And it doesn't try to run away, or breed nasty bacteria, or explode, or... Thank you for reminding me this. So on way could be: Storing the high temperatures with adobe/brick/stone and collecting the rest (below boiling point) of the heat with a water jacket. At least interesting for those with need of warm water. Breeding bacteria? Just keep the water over 55°C/140°F for a certain time.
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Post by photoman290 on Oct 22, 2014 7:21:18 GMT -8
i have managed to lift the roof of the yurt by about 10 inches so if i have the stove at ground level that should give me enough clearance. i am going to hang a sheet of ally from the roof so i have a air gap and put a sheet of masterboard on top. hopefully that should work. i have a IR thermometer so i can keep an eye on things. will start off using my waste oil burner which i know i can control before i try with a batch rocket. still be using the oil drum but instead of the rocket riser it will have the spike burner.
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