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element in bottom of kiln

updated wed 16 nov 05

 

Arnold Howard on wed 29 mar 00

Dear All:

What do you think of the heating element mounted in
the kiln's brick bottom? I've heard that it's main
advantage is in drying clay during candling.

Thanks,

Arnold Howard
Paragon

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Michael Banks on thu 30 mar 00

I would have thought that placing heating elements under the base shelf in
an electric kiln was designed to prevent the formation of a cold spot,
because this shelf (unlike those higher up), is only heated on the topside
and even on that side is in contact with the coolest, pooled, basal kiln
atmosphere. Heating the floor of the kiln results in convective overturn of
sinking cool atmosphere and ensures that the bottom shelf is not lagging
behind in temperature, which would result in undermature pots at the bottom
of the kiln.

In LPG/natural gas kilns, the idea of putting low wattage electric elements
in the floor or around the burner ports to facilitate drying/pre-heating,
has merit. One of the LPG gas kilns I owned at one stage (a 25 cu ft
Cotter, made in NZ) had single phase 240 volt circular coils in collars
around the four burner ports. Leaving these turned on overnight, raised the
kiln interior to about 150oC, ensuring perfectly dry pots. The effect of
this was more gentle than candling the burners, because the columns of
conductively heated air convectively rising above the burner ports was drier
and cooler than a flame - even a small one. Putting elements in the floor
of a down-draft gas kin would be superfluous in many well-designed units,
where the exiting flue gas (or a proportion of it) is ducted out under the
base shelves, which heats these sufficiently.

Michael Banks,
Nelson,
New Zealand

Arnold Howard wrote:
> ----------------------------Original message----------------------------
> What do you think of the heating element mounted in
> the kiln's brick bottom? I've heard that it's main
> advantage is in drying clay during candling.

Jonathan Kaplan on thu 30 mar 00

>----------------------------Original message----------------------------
>Dear All:
>
>What do you think of the heating element mounted in
>the kiln's brick bottom? I've heard that it's main
>advantage is in drying clay during candling.
>
>Thanks,
>
>Arnold Howard
>Paragon

My own feeling is that this is indeed a beneficial addition to electric
kilns when installed with its own infinite switch.

There are many advantages, the least of which is to even out the
tempertaure differential between the top and bottom.

It would be a nice addition to your TnF series of kilns!
Best

Jonathan

Jonathan Kaplan, president
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
voice and fax 970 879-9139
jonathan@csn,net
http://www.sni.net/ceramicdesigin

Dennis E. Tobin on thu 30 mar 00

Arnnold,
Sounds like a good idea but in a school situation (I teach at Miami
University in Ohio) where spent cones dropped in the bottom and glaze drips
occur at times, this has been a problem for our Cone Art kiln. Our oval
Cone Art kiln has a bottom element and it has been fried for a while . I
have a new one to replace it with, but I am reluctant because I am sure it
will be shot in a month or two as well. The kiln does fine without it.
Skutt has a new oval( I saw it in Denver) and it had fiber on the bottom
for added insulation.

may o>----------------------------Original message----------------------------
>Dear All:
>
>What do you think of the heating element mounted in
>the kiln's brick bottom? I've heard that it's main
>advantage is in drying clay during candling.
>
>Thanks,
>
>Arnold Howard
>Paragon
>
>__________________________________________________
>Do You Yahoo!?
>Talk to your friends online with Yahoo! Messenger.
>http://im.yahoo.com

Dennis Tobin
Associate Professor
Art Department
Miami University
Oxford, Ohio 45056
(513) 529-1505

Tracy Dotson on fri 31 mar 00

I think this is a great idea with one draw back. How to keep the chunks and
dust from collecting in the coil channel.

Tracy Dotson
The Pottery
Penland NC

Tommy Humphries on sat 1 apr 00

I have found that this setup can be very advantageous, especially when
firing flatter pieces on the bottom shelf.
I rigged up a kiln like this myself using a spare infinite controller and
some new elements. The leads were fed up from the bottom of the kiln through
the center with the element pinned directly to the floor. It was arranged
spiraling outward and was completely hidden by the bottom shelf.
Since there were no element grooves in the bottom of the kiln, extreme
caution was used to avoid damaging or shorting of the element.

Tommy Humphries

"`You know, it's at times like this, that I really wish I'd listened to what
my mother told me when I was young.'
`Why, what did she tell you?'
`I don't know, I didn't listen.'"
(Douglas Adams)




----- Original Message -----
From: Arnold Howard
To:
Sent: Wednesday, March 29, 2000 5:04 PM
Subject: Element in bottom of kiln


> ----------------------------Original message----------------------------
> Dear All:
>
> What do you think of the heating element mounted in
> the kiln's brick bottom? I've heard that it's main
> advantage is in drying clay during candling.
>
> Thanks,
>
> Arnold Howard
> Paragon
>
> __________________________________________________
> Do You Yahoo!?
> Talk to your friends online with Yahoo! Messenger.
> http://im.yahoo.com
>

Antoinette Badenhorst on tue 4 apr 00

I always had front loaders with an element in the bottom. The taller the kiln
become, the more important this element will be, because heat rises. I worked
with Scutt toploaders last year without an element in the bottom. We tested a
cone 4 in the bottom and a cone 5 higher up. This can make a big difference
in the successful firing of ones work. I guess that it might be worse when
want to fire to cone 10.
Antoinette(who just ordered my first kiln in the US)

Antoinette Badenhorst
PO Box 552
Saltillo,MS
38866

Arnold Howard on tue 15 nov 05


Maurice Weitman questioned me off-list about loading ware on a kiln bottom
that has element grooves. I thought about it further and realized that
someone might place ware right over a bottom element. That would melt the
ware and destroy the element! For that reason I should retract my earlier
post (below).

Sincerely,

Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com

> You should be able to fire ware that is placed directly on the kiln
> bottom. Raise the shelf so that there are a couple of rows of elements
> between the shelf and the kiln bottom.
>
> Sincerely,
>
> Arnold Howard
> Paragon Industries, L.P., Mesquite, Texas USA
> ahoward@paragonweb.com / www.paragonweb.com
>
> ----- Original Message -----
> From: "Debbie White"
>> How high off the floor should the bottom shelf be if there is an element
>> on
>> the bottom? My bottom tend to be the hottest....so I don't put the that
>> element on high...as it will overfire.
>