Kasia Bock-Leja on thu 17 jun 04
I'm having trouble with my 2 1/2 year old L&L, 7 cu. ft. model JD230-HC
with a Vent Sure system and computer. This is my first kiln so I do not
have the benefit of experience and comparison. Any advice would be
greatly appreciated.
9 months ago I replaced all the elements (and sprayed them lightly with
ITC for metal, per Mel's instructions) because the kiln could not reach
cone 6. The kiln had been fired about 1-2 times per month, and weekly
throughout the summer. A couple of firings later it became clear that
the elements were not the only problem and I replaced all the
thermocouples. I thought these replacements were premature. After
these replacements, the firing times were 9 hours for both the Fast
Glaze and Fast Bisque programs. I thought these times were good, but
maybe not?
Within 4 months, again firing about twice a month, the kiln is having
difficulty reaching temperature, taking about 10 hours for the Fast
programs. We noticed some melting at the prongs of the electrical
outlet, and also felt some heat there, so our electrician put a new cord
on the kiln and hard wired it. Feeling that the kiln was as good as
new, I decided to try the Vary Fire program, following John and Ron's
schedule. I had 2 perfect 9 hour bisque fires and then tried the glaze.
The kiln gets stuck at Segment 3, never getting into the hold portion.
Over fired and pitted work are the result.
I have been talking with the L&L consultant, who has helped with quite a
number of programing issues, which I have really appreciated (offsets,
etc.) He suggested that the elements need replacing and asked me to
check the ohms reading. Indeed, the numbers are 15.6/15.3/14.8 on the
prongs on the element plugs, indicating that even though the kiln has
only been fired 18 times in the last 9 months to cone 6 and 06, they
need replacing again.
The consultant also suggested that I check the amps while the kiln is
running to make sure it is getting enough power. He said to make sure
the kiln was actually running, pull one of the black element plugs part
way out and take the reading from there. I did this with my husband,
who is generally good with electrical items. With the amp meter, we
made contact with both flat plugs and immediatly caused a bright flash
and pop that created a short that tripped the breaker to the kiln.
After cutting power to the kiln from the master switch we reset the
tripped breaker. After restoring power to the kiln it would not turn
on. The LED read out only displayed a quick flash, and went dead.
After repeated attempts we get the same result with the LED read out.
The fuse on the controller box looks normal.
I am using a white stoneware clay and am not brushing oxides on my pots.
Most of the glazes I use are from Cone 6 glazes, as I am just starting
to work on my own glazes. Are these glazes known to be volatile and as
a result cause premature element aging? I pack the kiln lightly on the
bottom, heavy in the middle, and a little lighter on the top. I run the
vent through the whole firing as well as during cool down. I have
allowed some ware to hang over the edge of the shelves, maybe 2-3 per
shelf if the load was large. I was just advised against this, and the
suggestion has been made that I loosen the load.
I seriously need some advice here. I can't believe this is just normal
wear and tear, otherwise how many potters would be using electric kilns?
One discouraged potter,
Kasia in Madison, WI where the sun is finally shinning, but not on my
studio
Arnold Howard on fri 18 jun 04
Kasia, the problem may be low voltage under load. That can double the firing
time and wear out elements.
Low voltage causes the elements to "struggle" to reach the shutoff
temperature. That is very hard on elements.
Have an electrician check voltage under load. Until you know the voltage, an
amp reading won't tell you much, because low voltage also causes low
amperage.
Another possibility: Do you notice water condensing on the kiln case? Wet
greenware will slow down the firing.
Sincerely,
Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
arnoldhoward@att.net
----- Original Message -----
From: "Kasia Bock-Leja"
> I'm having trouble with my 2 1/2 year old L&L, 7 cu. ft. model JD230-HC
> with a Vent Sure system and computer. This is my first kiln so I do not
> have the benefit of experience and comparison. Any advice would be
> greatly appreciated.
>
> 9 months ago I replaced all the elements (and sprayed them lightly with
> ITC for metal, per Mel's instructions) because the kiln could not reach
> cone 6. The kiln had been fired about 1-2 times per month, and weekly
> throughout the summer. A couple of firings later it became clear that
> the elements were not the only problem and I replaced all the
> thermocouples. I thought these replacements were premature. After
> these replacements, the firing times were 9 hours for both the Fast
> Glaze and Fast Bisque programs. I thought these times were good, but
> maybe not?
>
> Within 4 months, again firing about twice a month, the kiln is having
> difficulty reaching temperature, taking about 10 hours for the Fast
> programs. We noticed some melting at the prongs of the electrical
> outlet, and also felt some heat there, so our electrician put a new cord
> on the kiln and hard wired it. Feeling that the kiln was as good as
> new, I decided to try the Vary Fire program, following John and Ron's
> schedule. I had 2 perfect 9 hour bisque fires and then tried the glaze.
> The kiln gets stuck at Segment 3, never getting into the hold portion.
> Over fired and pitted work are the result.
Clay Firer on fri 18 jun 04
I've had problems with long firings and error messages and after replacing everything that could be replaced I went into the electrical panel and found almost burnt wiring. I called in an electrician and he quickly diagnosed the problem as insufficiant gauge wire. He replaced the wiring and fixed the kiln.
---------------------------------
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Stephen J Lewicki on fri 18 jun 04
To all (and especial Kasia)
Thanks for the helpful comments from Arnold and "Clay Firer".
I spoke with Kasia this morning. I have refined and expanded on some of
what we discussed as follows:
There are many factors that affect element life and there are numerous
threads in the Clayart archives that address this. It is always frustrating
when you don=92t get the life out of elements or thermocouples that you
expect. The kiln in question here had our older exposed 8 gauge
thermocouples and Kasia has replacements plus our new ceramic protection
tubes, which according to both our tests and impirical evidence over the
past two years of use, have significantly improved thermocouple life. She
hasn't put the tubes in yet but will wait for a less busy time to do so.
The element issue is more difficult to diagnose - however, regardless of
the cause we have what should be a solution to her specific problem.
First, however, the matter of applying ITC coating to the elements needs to
be addressed and this is as good a time and place to do so. I am not
totally sure how the ITC coating works but this is my best understanding
after speaking with the folks at ITC and doing my own research. Number one
it protects the surface of the element from chemical attack (especially
from carburizing from carbon rich atmospheres - which can strongly affect
element life). Number two, and I am less certain of this, it is supposed to
improve radiation from the element. It may do these things and that may
improve element life in many cases. However, it is clearly not a panacea
for all element problems. Here is what I think the problem is. ITC is a
surface coating. Therefore it is adding to the thickness dimension of the
element wire. If the stretch between the coils happens to be on the low
side (which is the case with the elements in this kiln) then the space
between the hot coils becomes less and the element can overheat which
accelerates the aging process. I have seen ITC element coating be a problem
in one other instance. That being said, I am keeping an open mind on this
issue. We are working with a fine potter by the name of Ken Nowick to build
a specially made JD230 with ITC coating on the brick and maybe the
elements =96 maybe we will experiment =96 with a gas burner for gas/electric=
effects. I know Ken will be happy to share his experiences with the Clayart
community as the project progresses.
As far as the problem with the JD230 elements we are sending Kasia a new
set of our Easy-Fire e23T elements with a revised nameplate. For historical
reasons (having to do with the infinite switches of the manual J230 kilns)
the amperage of the JD230 is only 44 amps. When we started from scratch to
design the new Easy-Fire kiln models we designed those elements to take
full advantage of the 48 amp limitation of the 50 amp plug. These new
elements will give Kasia 10% more power than her JD230 had. Typically we
say the elements are aged when they lose less than that percentage so, even
as these elements go through their natural aging process (and even if she
has low voltage under power or some other problem) these new elements will
have the juice to deliver the results she should expect.
For future buyers these elements are available as a no charge option on our
JD230 kilns. The downside is that such a kiln can not be expanded which
typically is not a big issue for most users.
By the way, according the Kasia the controller seems to fine and, if not,
we will replace it. I told Kasia that hard wiring the kiln is a good thing -=
it eliminates a potential trouble spot. She thinks perhaps that the weight
of the plug may have slightly pulled the prongs from the receptical (which
would have reduced the contact area and perhaps lead to overheating.
Stephen Lewicki
President, L&L Kiln Mfg. Inc.
610-485-1789
steve@hotkilns.com
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