Hank Murrow on mon 30 aug 10
Dear Jonathan;
I helped fire Lee's "modified Euan-design" in Mashiko, and found it =3D
delightful to fire, providing spaces for cone 8 to cone 12 pots, =3D
depending upon location in the chamber. Not too tiring, and fast to =3D
fire. Not much ash deposited, however. Excellent as a soda kiln!
Cheers, Hank
On Aug 30, 2010, at 4:16 PM, jonathan byler wrote:
> I am considering building a wood kiln with a bourrey box, but attached
> to fireboxes under neath something much like euan craig's little
> downdraught style kiln.
>=3D20
> http://www.d1.dion.ne.jp/~euan/sub5-2.htm
>=3D20
> We were thinking this might be a little easier to fire, since you
> could stand up while stoking, and that perhaps the extra 4 feet or so
> under the kiln for the flame to travel in would cause more of the heat
> to to stay in the ware chamber instead of going up the chimney. any
> thoughts? can anyone think of why this extra space and flame path
> under the floor would lead to problems down the line? we actually are
> looking at building very similar to euan's design, but with a door in
> the side instead of in the front for loading. This would allow us to
> more easily attach a sliding/swinging door for more easy access to the
> kiln (I don't enjoy bricking up the doors!) We were thinking to start
> with his design, and then possibly add the bourrey box later if we
> decide we want to give that a try. Kiln is going to be for teaching
> purposes, but we also want it to be efficient.
jonathan byler on mon 30 aug 10
I looked at this, but it is just a standard small bourry box kiln.
what I am talking about, the flames would go under the floor towards
the back of the kiln, enter at the back and swirl around through the
ware and then go down and out through a flue in the floor between the
fireboxes and out the back of the kiln.
On Aug 30, 2010, at 9:32 PM, Les wrote:
> Ceramics Monthly June/July/August 1996
Les on mon 30 aug 10
Jonathan -=3D20
get a copy of Ceramics Monthly June/July/August 1996. Look for pages 44 =
=3D
& 45. You will find exactly what you are describing in this post.
The kiln is designed by Graham Sheehan on Gabriola Island, B.C. =3D
(Vancouver Island)
He built one for me in 2002 and it fires better every firing. You would =
=3D
love it.
Cheers,=3D20
Les Crimp in Nanoose Bay, B.C. (Vancouver Island)
On 2010-08-30, at 4:16 PM, jonathan byler wrote:
> I am considering building a wood kiln with a bourrey box, but attached
> to fireboxes under neath something much like euan craig's little
> downdraught style kiln.
>=3D20
> http://www.d1.dion.ne.jp/~euan/sub5-2.htm
>=3D20
> We were thinking this might be a little easier to fire, since you
> could stand up while stoking, and that perhaps the extra 4 feet or so
> under the kiln for the flame to travel in would cause more of the heat
> to to stay in the ware chamber instead of going up the chimney. any
> thoughts? can anyone think of why this extra space and flame path
> under the floor would lead to problems down the line? we actually are
> looking at building very similar to euan's design, but with a door in
> the side instead of in the front for loading. This would allow us to
> more easily attach a sliding/swinging door for more easy access to the
> kiln (I don't enjoy bricking up the doors!) We were thinking to start
> with his design, and then possibly add the bourrey box later if we
> decide we want to give that a try. Kiln is going to be for teaching
> purposes, but we also want it to be efficient.
>=3D20
> on another note, is a smallish (40-60 cf) side draught woodfired kiln
> less effecient than a downdraught type because the flame path is so
> short? I noticed that all the fastfire designs are downdraught
> types. I am looking at ways to lengthen the flame path of a side
> draught while still keeping a relatively small footprint. we are
> interested in the side draught kilns for the more directional
> imprinting of the flame on the ware, but would like to have more
> efficiency and consistency of firing that is offered by the
> downdraught kilns.
jonathan byler on mon 30 aug 10
I am considering building a wood kiln with a bourrey box, but attached
to fireboxes under neath something much like euan craig's little
downdraught style kiln.
http://www.d1.dion.ne.jp/~euan/sub5-2.htm
We were thinking this might be a little easier to fire, since you
could stand up while stoking, and that perhaps the extra 4 feet or so
under the kiln for the flame to travel in would cause more of the heat
to to stay in the ware chamber instead of going up the chimney. any
thoughts? can anyone think of why this extra space and flame path
under the floor would lead to problems down the line? we actually are
looking at building very similar to euan's design, but with a door in
the side instead of in the front for loading. This would allow us to
more easily attach a sliding/swinging door for more easy access to the
kiln (I don't enjoy bricking up the doors!) We were thinking to start
with his design, and then possibly add the bourrey box later if we
decide we want to give that a try. Kiln is going to be for teaching
purposes, but we also want it to be efficient.
on another note, is a smallish (40-60 cf) side draught woodfired kiln
less effecient than a downdraught type because the flame path is so
short? I noticed that all the fastfire designs are downdraught
types. I am looking at ways to lengthen the flame path of a side
draught while still keeping a relatively small footprint. we are
interested in the side draught kilns for the more directional
imprinting of the flame on the ware, but would like to have more
efficiency and consistency of firing that is offered by the
downdraught kilns.
jonathan byler on tue 31 aug 10
I saw another thing in olsen's book where he talks about it taking
about 4 to 5 feet per second as the ideal speed of the draught going
through the kiln in order to , so a kiln that is 45 feet from firebox
mouth to chimney exit ought to take about 10 seconds for the gasses to
exit while at temperature (around and above 2000F). Still trying to
figure from a design perspective how one can plan to make it right the
first time. He suggests throwing an oily rag in and counting how long
it takes for the smoke to show up out the chimney to get an estimate
of the draught speed.
Also still curious about how the length developed in a longer firebox
(in my case looping from the bourrey box under the kiln floor might
contribute to more of the heat from the flame staying inside the kiln.
The other thing I will be experimenting with is ways to maximize
preheating of primary and secondary combustion air for more efficient
firings. I have been thinking about channelling incoming air over the
top of the arch, and possibly though a series of small passages in the
chimney or in a collection box between the chimney and flue. if
secondary combustion air is added after the ware chamber in a
collection box, unburned gasses and soot could be burned off (reducing
pollution and smoke, and that heat used to preheat the primary air).
This ties in a bit to my question of where the main damper belongs,
and perhaps indicates that I need two of them; one in or before the
flue, and another above the collection box, along with some passive
dampers to control chimney draught.
On Aug 30, 2010, at 9:39 PM, jonathan byler wrote:
> I looked at this, but it is just a standard small bourry box kiln.
> what I am talking about, the flames would go under the floor towards
> the back of the kiln, enter at the back and swirl around through the
> ware and then go down and out through a flue in the floor between
> the fireboxes and out the back of the kiln.
>
>
> On Aug 30, 2010, at 9:32 PM, Les wrote:
>
>> Ceramics Monthly June/July/August 1996
>
gary navarre on wed 1 sep 10
That almost sounds like a small double cross-draft I fired to ^10 on my own=
=3D
except there was no need to down draft. The exit flue was at floor level a=
=3D
t the bottom of the chamber wall and into the stack base above the firebox.=
=3D
You load from the other side and the door ends up being the bag-wall to tu=
=3D
rn the flame 180=3DB0 from under the floor into the chamber. Some have sugg=
es=3D
ted the chimney on top of the firebox helps start the draft and keep it goi=
=3D
ng.=3D0A=3D0AGary Navarre=3D0ANavarre Pottery=3D0ANavarre Enterprises=3D0AN=
orway, Mic=3D
higan, USA=3D0Ahttp://www.youtube.com/GindaUP=3D0Ahttp://public.fotki.com/G=
inda=3D
UP/=3D0A=3D0A=3D0A--- On Mon, 8/30/10, jonathan byler =
wrote:=3D
=3D0A=3D0A> From: jonathan byler =3D0A> Subject: Re: [C=
layart=3D
] wood kiln firebox design=3D0A> To: Clayart@LSV.CERAMICS.ORG=3D0A> Date: M=
onda=3D
y, August 30, 2010, 9:39 PM=3D0A> I looked at this, but it is just a=3D0A> =
stan=3D
dard small bourry box kiln.=3D0A> what I am talking about, the flames would=
g=3D
o under the=3D0A> floor towards=3D0A> the back of the kiln, enter at the ba=
ck a=3D
nd swirl around=3D0A> through the=3D0A> ware and then go down and out throu=
gh a=3D
flue in the floor=3D0A> between the=3D0A> fireboxes and out the back of th=
e ki=3D
ln.=3D0A> =3D0A> =3D0A> On Aug 30, 2010, at 9:32 PM, Les wrote:=3D0A> =3D0A=
> > Cerami=3D
cs Monthly June/July/August 1996=3D0A> =3D0A=3D0A=3D0A
douglas fur on sat 4 sep 10
Jonathan
Speaking of old CM (I'm vague on the name here vannorstad ? vannorstrand?
independent guy working in Appalachis...) any way a kiln similar to your
concept
In addition to "simpler is better" I think in an under the floor draft
alot of flame effect would be lost due to ash settling out.
The inter arch pre-heat is one David stannard used in his sawdust fired
kiln. A catenary with two fire boxes he fired to about ^10/12. the arch
layers were seperated about1/2". air flowed up the arch to the peak then
down two internal air ducts to below floor level whence channels led under
the floor to exit just in front of the firemouth into the kiln.
I think it would be simpler to use kiln shelves to form double walls on eac=
h
side of the firebx. Air would come in the side preheat and exit around the
fire mouth co-axial with the flame.
DRB
Seola Creek
Mayssan Farra on sun 5 sep 10
DRB said;
>Speaking of old CM (I'm vague on the name here vannorstad ? vannorstrand?
>independent guy working in Appalachis...) any way a kiln similar to your
>concept
That would be Brian Van Nostrand doing his wonderful pottery in Hacker Vall=
ey WV
Mayssan Shora Farra
http://www.clayvillepottery.com
http://clayette.blogspot.com
Lee Love on sun 5 sep 10
On Sat, Sep 4, 2010 at 4:21 PM, douglas fur <23drb50@gmail.com> wrote:
> Jonathan
>
> Speaking of old CM (I'm vague on the name here vannorstad ? vannorstrand?
> independent guy working in Appalachis...) any way a kiln similar to your
> concept
>
> =3DA0In addition to "simpler is better" =3DA0I think in an under the floo=
r dr=3D
aft
> alot of flame effect would be lost due to ash settling out.
This was the design of my Mashiko kiln. You get no ash in
the flue channel, only vapor. The flame path goes to the roof, along
the ceiling and down the door. All the ash is deposited before the
channel. But you get excellent flashing with cone 6-8 Bizen clay
there.
--
=3DA0Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
jonathan byler on tue 7 sep 10
Simpler is better up to a point, but somewhere along the line one
would need to make things a little more complex in order to achieve
more efficiency. I keep forgetting that I could use old kiln shelves
as building blocks here. that opens up some possibilities.
one thing I *don't* want to do is steal heat from somewhere in the
kiln where I actually need it. so I am a little leary of using my
firebox walls as preheat space. I want the heat from the firebox
flowing into the ware chamber. so I am going to run IFB or insulated
castable all the way down to the bottom of the firebox. I think
stealing heat from a collection chamber between the flue exit and the
main chimney would be best, since the heat going up is just waste
(except for the amount needed to help the draught). I was thinking
about running preheat air over the top of the kiln because most of the
kilns I have ever dealt with tend to be hotter up top anyway.
regardless, I have found some ways to leave a good bit of this open to
change after the fact, so that If my heat recycling schemes don't work
or worst case cause detriment to the efficiency of the firing, they
can be easily bypassed or removed before subsequent firings.
-jon
On Sep 4, 2010, at 4:21 PM, douglas fur wrote:
> Jonathan
>
> Speaking of old CM (I'm vague on the name here vannorstad ?
> vannorstrand? independent guy working in Appalachis...) any way a
> kiln similar to your concept
>
> In addition to "simpler is better" I think in an under the floor
> draft alot of flame effect would be lost due to ash settling out.
>
> The inter arch pre-heat is one David stannard used in his sawdust
> fired kiln. A catenary with two fire boxes he fired to about ^10/12.
> the arch layers were seperated about1/2". air flowed up the arch to
> the peak then down two internal air ducts to below floor level
> whence channels led under the floor to exit just in front of the
> firemouth into the kiln.
>
> I think it would be simpler to use kiln shelves to form double walls
> on each side of the firebx. Air would come in the side preheat and
> exit around the fire mouth co-axial with the flame.
>
> DRB
> Seola Creek
douglas fur on tue 14 sep 10
Jonathan
> one thing I *don't* want to do is steal heat from somewhere in the
> kiln where I actually need it.
This concept is a riff on a design shown in Bourry and Cardew refers to it
in his discussion of fire boxes. Yes it would take heat from the firebox
but it would end up in the ware chamber and improving the combustion it
would end up with more heat going to the pots by burning fuel that would go
up the chimney otherwise.
> stealing heat from a collection chamber between the flue exit and the
> main chimney would be best, since the heat going up is just waste
>
This is like an oil fired kiln David Stannard built in Alaska. It had a
double walled chimney, exhaust in the middle and secondary air drawn down i=
n
the outer layer to a collection box at the base.
From the collection box channels went to each side of the kiln up inside
the walls to an air plenum and then into a chamber to mix with vaporized
oil.
> I was thinking about running preheat air over the top of the kiln becaus=
e
> most of the
> kilns I have ever dealt with tend to be hotter up top anyway.
The one I've thought about would put a false bottom to the trench leading t=
o
the chimney. This false bottom could be kiln shelves, steel plate or
Titanium sheet. Secondary air would enter below this, get heated and then
exit to the firebox area.
I printed out Euan's article to look at . It seems like a good fit to put =
a
Bourry box on each side. This would change the flow pattern- for symetry
I'd put an additional exit from the firebox to the ware chamber.
For efficiency...
Theory says heat loss is from the surface therefore the best place for the
heat to enter a kiln would be the middle so that it would flow out to the
surface . So why not a cubic kiln with one fire box feeding a central
riser and flue exits around the perimeter?
DRB
Seola Creek
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