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cold conversion kiln firing

updated wed 27 oct 99

 

Joanne Van Bezooyen on fri 22 oct 99

I tried firing my electric-converted to natural gas-kiln today and after
11 hours....a yellow orange chamber...and cone 4 wouldn't bend, let
alone cone 5! I feel awful about it. So much money and work.... :~(

What do I need to do now? Could the brick walls be too thin? Too many
cracks in the peepholes and layers ? Summit said they'd drill holes for
our gas pressure # which we gave them. There are 2 burners in the
bottom of a 17" hexagonal kiln...shooting up....4" square hole on
top.....

I'm going to bed......

Joanne in Tucson where the sun does a better job than my converted kiln
just did :~(

Ray Aldridge on sat 23 oct 99

At 10:33 AM 10/22/99 EDT, you wrote:
>----------------------------Original message----------------------------
>I tried firing my electric-converted to natural gas-kiln today and after
>11 hours....a yellow orange chamber...and cone 4 wouldn't bend, let
>alone cone 5! I feel awful about it. So much money and work.... :~(
>

The kiln gurus will probably have better advice for you, but don't be too
discouraged. Fuel-burning kilns are different and take a little time to
learn to fire well. If you don't have a pyrometer, you probably ought to
get one, because then you can play with the damper setting and the valves
and the primary air inlets on your burners until you find the best
combination. Unless your burner orifices are way off, you should be able
to reach temp, once you've learned a bit more about it. The changes in
these setting can be very subtle-- just a small change in the damper or
primary air can have a big effect on the rate of temperature rise.

Hang in there! I predict it will go better next time.

Ray



Aldridge Porcelain and Stoneware
http://www.goodpots.com

Joanne Van Bezooyen on sun 24 oct 99

Ray....What is the 'primary air' source? Our burners are under the
kiln...straight up....no forced air, just holes in the bottom of the kiln
that are larger than the burners.

Re. the orifices, my husband asked Summit kilns to set the orifices ot 7"
natural gas pressure. Summit says 11" is normal but that 7" would actually
give us more fuel and not be a problem at all.

I haven't heard from any kiln 'gurus'....a conversion must be too small of
potatoes for them to be interested.

Ray Aldridge wrote:

> ----------------------------Original message----------------------------
> At 10:33 AM 10/22/99 EDT, you wrote:
> >----------------------------Original message----------------------------
> >I tried firing my electric-converted to natural gas-kiln today and after
> >11 hours....a yellow orange chamber...and cone 4 wouldn't bend, let
> >alone cone 5! I feel awful about it. So much money and work.... :~(
> >
>
> The kiln gurus will probably have better advice for you, but don't be too
> discouraged. Fuel-burning kilns are different and take a little time to
> learn to fire well. If you don't have a pyrometer, you probably ought to
> get one, because then you can play with the damper setting and the valves
> and the primary air inlets on your burners until you find the best
> combination. Unless your burner orifices are way off, you should be able
> to reach temp, once you've learned a bit more about it. The changes in
> these setting can be very subtle-- just a small change in the damper or
> primary air can have a big effect on the rate of temperature rise.
>
> Hang in there! I predict it will go better next time.
>
> Ray
>
> Aldridge Porcelain and Stoneware
> http://www.goodpots.com

Ray Aldridge on mon 25 oct 99

At 07:40 PM 10/24/99 EDT, you wrote:
>----------------------------Original message----------------------------
>Ray....What is the 'primary air' source? Our burners are under the
>kiln...straight up....no forced air, just holes in the bottom of the kiln
>that are larger than the burners.

Primary air is that air which is entrained by the gas within the burner,
and is adjusted using various devices, depending on the burner. I assume
your burners are simple atmospheric burners, and in most cases the primary
air shutter is just a flat flange threaded onto the bottom pipe of the
burner. You adjust it by rotating the shutter so it's closer to or farther
from the air inlet. A reasonable starting point is to close the shutter
until the flame goes yellow (and smoky) and then open it just enough to let
the flame get bright and blue again. Too much primary air cuts down the
efficiency of the burner, because more cold air than is needed for
combustion is being drawn in,

Secondary air is the air drawn in through the holes in the bottom of the
kiln by the draft. You control this by adjusting the damper at the top of
the kiln. It's my opinion that a good starting point for figuring out the
best settings for maximum efficiency is this: adjust the burners as I
suggested above, and then close the damper until you get slight reduction
(do this in the dark so you can see the flame coming from the top peephole)
and then open the damper just enough to make this peephole flame disappear.

Anyway, it sounds complicated, but you'll catch on quick.

Ray



Aldridge Porcelain and Stoneware
http://www.goodpots.com

Joanne Van Bezooyen on tue 26 oct 99

Thanks Ray,
I understand the secondary air part now.

As for primary air adjustment, I think I'll have to call Summit kilns. These
burners are made of a horizontal 1" pipe the gas comes in through. There is a
tiny hole through a nut-type looking thing at each burner sight. Placed
vertically on top of each 'nut-hole' are 2" side pipes which are completely
open.top and bottom and no adjustments at all. A thin gas tube runs to a hole
at the top of each pipe for pilots. I think is a very simple system. My kiln
is very small for a gas.
Joanne

Ray Aldridge wrote:

> ----------------------------Original message----------------------------
> At 07:40 PM 10/24/99 EDT, you wrote:
> >----------------------------Original message----------------------------
> >Ray....What is the 'primary air' source? Our burners are under the
> >kiln...straight up....no forced air, just holes in the bottom of the kiln
> >that are larger than the burners.
>
> Primary air is that air which is entrained by the gas within the burner,
> and is adjusted using various devices, depending on the burner. I assume
> your burners are simple atmospheric burners, and in most cases the primary
> air shutter is just a flat flange threaded onto the bottom pipe of the
> burner. You adjust it by rotating the shutter so it's closer to or farther
> from the air inlet. A reasonable starting point is to close the shutter
> until the flame goes yellow (and smoky) and then open it just enough to let
> the flame get bright and blue again. Too much primary air cuts down the
> efficiency of the burner, because more cold air than is needed for
> combustion is being drawn in,
>
> Secondary air is the air drawn in through the holes in the bottom of the
> kiln by the draft. You control this by adjusting the damper at the top of
> the kiln. It's my opinion that a good starting point for figuring out the
> best settings for maximum efficiency is this: adjust the burners as I
> suggested above, and then close the damper until you get slight reduction
> (do this in the dark so you can see the flame coming from the top peephole)
> and then open the damper just enough to make this peephole flame disappear.
>
> Anyway, it sounds complicated, but you'll catch on quick.
>
> Ray
>
> Aldridge Porcelain and Stoneware
> http://www.goodpots.com