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(still) gas kiln questions & problems. - long response

updated tue 11 jul 06


William & Susan Schran User on mon 10 jul 06

On 7/9/06 9:02 PM, "marianne kuiper milks"

> Can anyone give me reasons why the Olympic top-loading, 4 burner #...G
> produces so much smoke and soot?
> What can I do about it?

I've written previously about all my difficulties/issues with my Olympic
updraft kiln.

I got the kiln 1/2 price used, but the kiln had only been fired 3 times by
the original owner. The bottom of the kiln and the burner ports were all
covered with soot. I just figured the guy didn't know what he was doing.

After I got the kiln home and set-up with propane as the fuel and regulator
installed to limit pressure per the kiln manufacturer's written
instructions, I lit it for the first firing. I noted right away a yellow
flame from the burners, instead of a blue flame, even though primary air
disks were wide open. I also noted some back burn from the burners - flames
coming out the back of the burners! Turning up the pressure, opening all the
way, seemed to be the only way to stop the back burning.

I followed up with a glaze load. Again I faced the problem of back burning.
Then the kiln began shutting off. I'd relight, it would go along fine, then
shut off. Finally figured out the thermocouple was not set in the flame path

I think your problems are with the burners themselves. They are cheap pipe
burners and I think they actually require more pressure to operate properly.
But if you use too much pressure, temperature will climb too fast. But also
the Baso valve installed with the kiln has a 1/2lb limit, so that would need
to be changed out if one wanted to go high pressure. Even then, with more
gas pressure, I'm not certain you wouldn't be building up too much back
pressure and stalling the kiln anyway.

My solution was to yank out the original burners, lighting tube and pilot
burner/thermocouple. I replaced them with three MR-750 Venturi burners and a
heavy duty pilot/thermocouple. The thermocouple is on the first burner in
the gas line. This now means I have to reach under and light the other two
burners independently.

I got the burners and safety from Marc Ward. When I called him, had a nice
long conversation - he was reluctant to make any comments about Olympic gas
fired kilns for fear he'd get into trouble. Let's just say he doesn't hold
Olympic in the highest regard. Well into the talk, he told me he had gotten
several calls about firing issues with Olympic kilns. He wouldn't guarantee
the burners he was selling me would work.

I had to do some very minor metal cutting to remove the "burner" tube, but
the new burners were about the same length as the originals, so they fit
right in. The new burners operate just fine on very low pressure and
maintain a nice oxidizing flame. They are a bit overpowered for the size of
the kiln. I could probably remove the middle burner and have the kiln fire
to temperature just fine. My firings to ^6 last about 5-6 hours and I'm able
to get fairly even temperatures top to bottom.

Well, that's how I solved my issues with my kiln.

I really think the problem is with the burners. The design simply demands a
greater flow of gas to burn properly. Back when I was attempting to fix the
original burners, I had one person write to me about how he added a flame
retention device on the end of the burner to get his to work.

Oh yeah, I did contact Olympic and spoke with the president of the company,
Robert Hauger I think is his name. After explaining my problems, he didn't
seem to be able to come up with a definitive solution. I requested a copy of
the "updated" firing instructions - never got it.

-- William "Bill" Schran
Fredericksburg, Virginia