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Hello Darren and Crispin,<br>
<br>
I have played with some of these gravity hopper or down feed
burners, both large and small. I would like to point out the
obvious, that your "playing with fire" and risking explosion. Often
its a minor 'POOF' but it is still enough to send smoke and sparks
back through air intakes and into places you don't want them to go.
That is what can happen when you trap combustible gasses. If your
using very dry wood you can generate potent gasses.<br>
<br>
You have taken on a tricky task. I am trying something similar too.
If I learn something useful I'll let you know. <br>
<br>
Good Luck<br>
<br>
Alex<br>
<br>
<br>
On 09/01/2012 3:26 PM, Darren wrote:
<blockquote cite="mid:4F0B4D84.2050701@vegburner.co.uk" type="cite">
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Hello Crispin,<br>
<br>
I was using some reclaimed construction timber, pine/conifer,
2"x2" and cutting it to short lengths.<br>
<br>
I was only opening the lid on top of the fuel hopper to push the
fuel through under the bridge, to look at what was happening
inside or to add more fuel. I appreciate that when I've got
things set up properly I only really want to open it to refuel. I
was slightly surprised to find the hopper full of smoke - I guess
I was expecting the air in the hopper to remain static - happy to
hear that this is normal.<br>
<br>
The wood on the hopper side of the grate was catching alight
well. The flames did appear to die back significantly when the
wood/embers that were on the combustion chamber side of the grate
had burnt away. I guess more testing will tell more. <br>
<br>
The original grate is not shakeable, the new one that is sitting
on top is. I did this so I can vibrate ;) the fuel down the
grate. I've now got 9cm from grate up to the bridge and this
throat is about 10cm wide.<br>
<br>
Hopefully I'll get a chance to fire it up with the new grate later
in the week. I was thinking about experimenting with covering
some of the back of the grate. I'll cut some metal to fit and try
this at some point also.<br>
<br>
I guess ideally it would run without needing to shake the grate.
Unfortunately, the way the thing is constructed, lifting the
bridge is not an easy option. I could more easily lower the grate
which would provide a bigger gap between grate and bridge and
allow for wood to fall through more easily, although I guess if
this will also effect the heat output? Also I guess a steeper
grate angle will help. <br>
<br>
Best<br>
<br>
Darren<br>
<br>
<br>
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