Jennifer Boyer on wed 3 nov 99
After searching the archives, I still am in a quandary:
I had my first firing of my new 39 cu ft IFB downdraft propane
kiln using(b-4 Ransome) venturi burners, rebuilt from my old
kiln. The old one had 4 burners mounted at the sides. This one
has 2 rear mounted burners. I have low bagwalls, 9 inches high
with spaces in them. I have my shelves up against the back wall,
which always worked in the old kiln. I also followed Vince's
advice and made a flue channel by laying the bottom shelves on 2
rows of brick to form the channel.
This firing was fairly even from top to bottom and fired in 12
hours to cone 10. The unevenness came from front to back. The
area against the back wall was cooler than the rest of the kiln.
I have plenty of room at the front of the kiln and want to move
the shelves forward, away from the back wall. I'm hoping that
this will encourage flow of heat to the back, as well as simply
moving the stack of shelves into the hotter part of the kiln. A
small part of the flue opening sticks up above the first shelf.
I might also lower the first shelf to expose more of the flue
opening above it.
Any ideas about evening out a kiln with rear mounted burners?
This is my first experience with anything other than sidemounted
burners.
Take Care
Jennifer
--
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jennifer Boyer jfboyer@sover.net
Thistle Hill Pottery
Vermont USA
http://www.vermontcrafts.com/members/ThistleHill.html
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Vince Pitelka on thu 4 nov 99
> This firing was fairly even from top to bottom and fired in 12
>hours to cone 10. The unevenness came from front to back. The
>area against the back wall was cooler than the rest of the kiln.
>I have plenty of room at the front of the kiln and want to move
>the shelves forward, away from the back wall. I'm hoping that
>this will encourage flow of heat to the back, as well as simply
>moving the stack of shelves into the hotter part of the kiln. A
>small part of the flue opening sticks up above the first shelf.
>I might also lower the first shelf to expose more of the flue
>opening above it.
Jennifer -
If you have your shelves right up against the back wall, then that is most
of your problem. You must always have good circulation all the way around
the set. Move your shelves out at least a few inches from the back wall.
When using the space beneath the bottom shelf as a flue-tunnel, I use pieces
of softbrick to extend the flue opening out to the shelves, rather than
moving the shelves back to the flue opening. This has always worked very
well for me on kilns with two rear-mounted burners.
Good luck -
- Vince
Vince Pitelka
Home - vpitelka@DeKalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
gwalker on thu 4 nov 99
G'day Jennifer,
I had a 54 cubic of the same configuration and fired it thousands of
times before it finally died. It was the most even kiln if stacked to
suit. Here are some clues I hope will help:
A rule of thumb: pack the hotter areas more tightly and the cooler areas
more loosely. I have found this to hold true for any kiln, regardless of
fuel.
You are on the right track when you suggest stacking the front shelves
closer to the front door and the ones in the rear further away from that
wall. I think you will also find that the coolest part of the kiln will
have been the top rear in the middle of the top shelf. This is where you
should put your taller pots, provided that there is space between them.
(What I mean here is that it is no good putting 20 tall cylinder pots
close together, for instance ... no place for gas to flow ... Spherical
forms would be more suited here.)
You might have to play around with the rear bottom shelf and it's
location and positioning. I would be inclined to leave the flue area as
is for a while and bring the bottom rear shelf forward so that the was
at least 2"of space between it and the wall.
Although I don't use this configuration in kilns currently, I have had
great success with it over the years.
Best of luck to you, and if you think I might be of any further help,
feel free to ask.
Geoff - on the Gold Coast where I can't believe we have had a couple of
unseasonally cool and windy days, and just now a sharp shower which came
from nowhere. ???
Jennifer Boyer wrote:
> ----------------------------Original
> message----------------------------
> After searching the archives, I still am in a quandary:
>
> I had my first firing of my new 39 cu ft IFB downdraft propane
> kiln using(b-4 Ransome) venturi burners, rebuilt from my old
> kiln. The old one had 4 burners mounted at the sides. This one
> has 2 rear mounted burners. I have low bagwalls, 9 inches high
> with spaces in them. I have my shelves up against the back wall,
> which always worked in the old kiln. I also followed Vince's
> advice and made a flue channel by laying the bottom shelves on 2
> rows of brick to form the channel.
>
> This firing was fairly even from top to bottom and fired in 12
> hours to cone 10. The unevenness came from front to back. The
> area against the back wall was cooler than the rest of the kiln.
> I have plenty of room at the front of the kiln and want to move
> the shelves forward, away from the back wall. I'm hoping that
> this will encourage flow of heat to the back, as well as simply
> moving the stack of shelves into the hotter part of the kiln. A
> small part of the flue opening sticks up above the first shelf.
> I might also lower the first shelf to expose more of the flue
> opening above it.
>
> Any ideas about evening out a kiln with rear mounted burners?
> This is my first experience with anything other than sidemounted
> burners.
>
> Take Care
> Jennifer
> --
> ~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
> Jennifer Boyer jfboyer@sover.net
> Thistle Hill Pottery
> Vermont USA
> http://www.vermontcrafts.com/members/ThistleHill.html
> ~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jeff & Melanie Boock on fri 5 nov 99
Would this configuration require a target brick in each firebox to
prevent the flame from shooting directly to the front wall of the
kiln and therefore cause the front of the kiln to be heated hotter
and faster than the rear?
I know this happened in a downdraft kiln we built, but it had power
burners firing from the rear, and that may have caused the flame to
have more velocity pushing it toward the front of the kiln. That
first firing without the target brick was really uneven from front to
back. I'm not sure if it is necessary with venturi burners, though.
Jeff Boock
>----------------------------Original message----------------------------
>After searching the archives, I still am in a quandary:
>
>I had my first firing of my new 39 cu ft IFB downdraft propane
>kiln using(b-4 Ransome) venturi burners, rebuilt from my old
>kiln. The old one had 4 burners mounted at the sides. This one
>has 2 rear mounted burners. I have low bagwalls, 9 inches high
>with spaces in them. I have my shelves up against the back wall,
>which always worked in the old kiln. I also followed Vince's
>advice and made a flue channel by laying the bottom shelves on 2
>rows of brick to form the channel.
>
> This firing was fairly even from top to bottom and fired in 12
>hours to cone 10. The unevenness came from front to back. The
>area against the back wall was cooler than the rest of the kiln.
>I have plenty of room at the front of the kiln and want to move
>the shelves forward, away from the back wall. I'm hoping that
>this will encourage flow of heat to the back, as well as simply
>moving the stack of shelves into the hotter part of the kiln. A
>small part of the flue opening sticks up above the first shelf.
>I might also lower the first shelf to expose more of the flue
>opening above it.
>
>Any ideas about evening out a kiln with rear mounted burners?
>This is my first experience with anything other than sidemounted
>burners.
>
>Take Care
>Jennifer
>--
>~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
>Jennifer Boyer jfboyer@sover.net
>Thistle Hill Pottery
>Vermont USA
>http://www.vermontcrafts.com/members/ThistleHill.html
>~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Corinne P. Null on sat 6 nov 99
Jennifer,
We got a Bailey downdraft 20 cu foot with two burners placed like yours two
years ago. It was an education setting it up, but by following their
instructions it all went very smoothly. First, our bagwalls don't have any
spaces in them. By bagwalls, I'm referring to the first course of bricks
that the bottom shelves rest on. The flue opening rises up a bit above the
first course of shelves, which seeems to be fine. The shelves themselves do
not touch the back wall, but are about a finger width (1/2") from the wall.
The posts for the next shelves form part of the bagwall, with another
bagwall brick laying on it's side on the edge of the shelf, creating more of
a firing channel. There is also a target brick, placed half way front to
back in the flame channel to direct the flame upwards. Keep the shelves
that half inch from the back wall, and you should be golden. We stack the
bottom loosely, always using tall posts, the middle getting tighter packing.
Our kiln fires like a dream, and it sounds like you're real close to having
a beauty!
Best, Corinne
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.UKY.EDU]On Behalf
Of Jennifer Boyer
Sent: Wednesday, November 03, 1999 5:52 PM
To: CLAYART@LSV.UKY.EDU
Subject: downdraft kiln shelf placement
----------------------------Original message----------------------------
After searching the archives, I still am in a quandary:
I had my first firing of my new 39 cu ft IFB downdraft propane
kiln using(b-4 Ransome) venturi burners, rebuilt from my old
kiln. The old one had 4 burners mounted at the sides. This one
has 2 rear mounted burners. I have low bagwalls, 9 inches high
with spaces in them. I have my shelves up against the back wall,
which always worked in the old kiln. I also followed Vince's
advice and made a flue channel by laying the bottom shelves on 2
rows of brick to form the channel.
This firing was fairly even from top to bottom and fired in 12
hours to cone 10. The unevenness came from front to back. The
area against the back wall was cooler than the rest of the kiln.
I have plenty of room at the front of the kiln and want to move
the shelves forward, away from the back wall. I'm hoping that
this will encourage flow of heat to the back, as well as simply
moving the stack of shelves into the hotter part of the kiln. A
small part of the flue opening sticks up above the first shelf.
I might also lower the first shelf to expose more of the flue
opening above it.
Any ideas about evening out a kiln with rear mounted burners?
This is my first experience with anything other than sidemounted
burners.
Take Care
Jennifer
--
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jennifer Boyer jfboyer@sover.net
Thistle Hill Pottery
Vermont USA
http://www.vermontcrafts.com/members/ThistleHill.html
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
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