Elisa Root and John Frater on sun 6 aug 00
I just built my first kiln, a propane fired downdraft design made of soft
brick with dimensions of about 55"X56"X50" with an arched top. I have 4
burners rated at 150,000 btu's each with the propane system running at 13WC
pressure. I'm getting a good draft thru the chimney and the burners fire
with a green/blue color. I tried a test bisque but stopped at 1000F because
I'm only able to raise the temperature at about 100F per hour, even with
the flue damper nearly closed. This seems OK up to 600-700F, but once I
pass that temperature, I want to be able to raise the temperature more
quickly...any suggestions?
Cat Jarosz on mon 7 aug 00
Do you know the size of the orifice on the burners are??? Maybe Mark
Wardell can talk you thru that... I think I recall a friend having that
trouble and getting bigger orifices for the burners did the trick ... ps
just a wild guess on my part ...
ferenc jakab on mon 7 aug 00
> I just built my first kiln, a propane fired downdraft design made of soft
> brick with dimensions of about 55"X56"X50" with an arched top. I have 4
> burners rated at 150,000 btu's each with the propane system running at
13WC
Elisa,
Are you sure they are 150,000 Btu s? This would rate at 100,000 000 Joules.
My Eight 2" burners only produce 1,600 000 Joules or 1500 Btus according to
my conversion program.
A new kiln needs a burn in to expell excess moisture, did you do this?
Is this kiln double walled, I.e. sufficiently insulated against heat loss?
Are you drawing enough secondary air?
Feri,
A bit puzzled.
Donald G. Goldsobel on mon 7 aug 00
I read your message and am puzzled about your damper setting. When I do a
bisque firing the damper is open a good four inces at first and never less
than two inches-- that is in the up draft mode ( It is an updraft\downdraft
kiln I had built) Try leaving the damper open so there is no chance you
will go into a reduction state. If you want the temperature to advance give
the fuel enough air to have complete combustion.
Good Luck
Donald Goldsobel
I tried a test bisque but stopped at 1000F because
>I'm only able to raise the temperature at about 100F per hour, even with
>the flue damper nearly closed. This seems OK up to 600-700F, but once I
>pass that temperature, I want to be able to raise the temperature more
>quickly...any suggestions?
>
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