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calculating firing cost for electric kiln

updated sat 18 sep 99

 

Gregory D Lamont on mon 13 sep 99

I'm curious to find out what a firing costs in my L&L J-230 kiln (7 cu. ft.
capacity) The kiln is not metered separately from the rest of the house, so
it's difficult for me to tell what the kiln is using by itself.

My electricity costs $.07 per kilowatt hour and a typical firing takes
about 10 hours average to reach cone 6 on the ramping schedule I use. The
kiln is rated at 55 amps and 10,555 watts.

If anyone can tell me how to calculate this or, if anyone has figured out
how much their similar sized electric kiln costs and their electric cost
per kilowatt hour, so I can figure out my cost, I'd appreciate it.
TIA,
Greg
Greg Lamont
gdlamont@iastate.edu
http://www.ourwebpage.net/greglamont/

3011 Northwood Drive
Ames, IA 50010-4750
(515) 233-3442

John Rodgers on tue 14 sep 99

In my shop in Alaska I called the power company and they came out an put a
meter on my kiln through a complete firing...from the moment it was turned on
until it shut off. Every few seconds the meter would take a reading and print
it on a strip of paper. It gave me a good analysis over the complete firing
range. When it was done it was easy to arrive at the firing cost. As I recall,
it was something like $8.27 for firing a fully loaded kiln to cone 6. Course
that was some years ago, but the point is you can do the same. The power
company didn't charge anything for the service. Of course, they were providing
a service to a licenced business.

John Rodgers
In New Mexico

Gregory D Lamont wrote:

> ----------------------------Original message----------------------------
> I'm curious to find out what a firing costs in my L&L J-230 kiln (7 cu. ft.
> capacity) The kiln is not metered separately from the rest of the house, so
> it's difficult for me to tell what the kiln is using by itself.
>
> My electricity costs $.07 per kilowatt hour and a typical firing takes
> about 10 hours average to reach cone 6 on the ramping schedule I use. The
> kiln is rated at 55 amps and 10,555 watts.
>
> If anyone can tell me how to calculate this or, if anyone has figured out
> how much their similar sized electric kiln costs and their electric cost
> per kilowatt hour, so I can figure out my cost, I'd appreciate it.
> TIA,
> Greg
> Greg Lamont
> gdlamont@iastate.edu
> http://www.ourwebpage.net/greglamont/
>
> 3011 Northwood Drive
> Ames, IA 50010-4750
> (515) 233-3442

Maggie Woodhead on tue 14 sep 99

Hi Greg! Kia ora!
When I first got my electric kiln my
husband put a clock in line with the kiln. Across the contactor that
switches the elements on and off. No more idea of the electrical
details! However each firing I can read the actual time that the kiln
is operating and from that work out the actual cost of the electricity
used. I have worked out a K factor by which I multiply the hours and
minutes and have instant cost of each firing. Incidentally I have
found very little difference in costs when increasing the firing ramps
or soaks. The kiln holds its heat well, however a heavy load of pots
registers in the electricity used. Hope this info. is of some use.
Our clock was one picked up from an old electric stove ready for the
scrap heap.
We potters!!!!!!!!

----Best Wishes Maggie----
maggiew@clear.net.nz

Jim Cullen on tue 14 sep 99

Greg,
I used a pretty simplistic approach but it seems to work and didn't require a
PHd to figure. Over a couple of days I took hourly meter readings of the
normal operation of my house. From these readings I came up with an average
number of kilowatt hours the house used. When I setup to do a firing I write
down my current reading and then note the reading every hour (you could just
use a start and finish number). It is then simple math, subtract the smaller
number from the bigger and multiply by the cost/kw. Do this after subtracting
the average cost/hr which you figured out ahead of time.

I keep these costs in my computer along with my firing schedule and at the
end of the year I have an actual total cost for firing which I list as a
business expense for deductions.

Pretty simple. Does the job.

KEEP CENTERED
Cullen
Naperville, Illinois

Carol Seidman on tue 14 sep 99

Greg: To measure the electric consumption of your kiln, try this: Take a
reading of your electric meter at the start and end of your next firing.
Note the time duration of the firing. If it took 10 1/2 hours to fire
the kiln, lets say the total usage of power was 150 kilowatt hours.
Take the start and end reading of the meter for a 10 1/2 period when the
kiln is not firing. Do this several times to get an average usage for
power in your home. If that number came to 100, the difference is what
the kiln used, 50 KWH. Here in New Jersey, the rates are higher in the
summer. Happy metering.
Carol Seidman

Gregory D Lamont wrote:
>
> ----------------------------Original message----------------------------
> I'm curious to find out what a firing costs in my L&L J-230 kiln (7 cu. ft.
> capacity) The kiln is not metered separately from the rest of the house, so
> it's difficult for me to tell what the kiln is using by itself.
>
> My electricity costs $.07 per kilowatt hour and a typical firing takes
> about 10 hours average to reach cone 6 on the ramping schedule I use. The
> kiln is rated at 55 amps and 10,555 watts.
>
> If anyone can tell me how to calculate this or, if anyone has figured out
> how much their similar sized electric kiln costs and their electric cost
> per kilowatt hour, so I can figure out my cost, I'd appreciate it.
> TIA,
> Greg
> Greg Lamont
> gdlamont@iastate.edu
> http://www.ourwebpage.net/greglamont/
>
> 3011 Northwood Drive
> Ames, IA 50010-4750
> (515) 233-3442
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amy parker on tue 14 sep 99

Greg - I used the Scientific Wild Ass Guess method (SWAG) - I read the meter
when I flipped the kiln on and when I flipped it off. 24 hours later, I
took another reading, since the weather was almost identical. I took
another reading 24 hours after the shutoff had occurred. I did not use the
dryer during any of this time, and used the stove about the same amount of
time. I did another reading of non-kiln usage for the same time period on
another day, and found that the two non-kiln days were very close in usage,
so I estimated that the difference was the kiln. I then multiplied the
usage by the charges on my power bill, and came up with about $6.50 per
firing for my Olympic 2327H. Interestingly enough, after repeating this for
both bisque & cone 6 glaze firings, I am about equal for both - might be the
long slow bisque!

Amy, who is glad that the A/C is no longer sucking up all the electricity!

At 03:09 PM 9/13/99 EDT, you wrote:
>----------------------------Original message----------------------------
>I'm curious to find out what a firing costs in my L&L J-230 kiln (7 cu. ft.
>capacity) The kiln is not metered separately from the rest of the house, so
>it's difficult for me to tell what the kiln is using by itself.
>If anyone can tell me how to calculate this or, if anyone has figured out
>how much their similar sized electric kiln costs and their electric cost
>per kilowatt hour, so I can figure out my cost, I'd appreciate it.
>TIA,
>Greg
amy parker Lithonia, GA
amyp@sd-software.com

pvw on wed 15 sep 99

> My electricity costs $.07 per kilowatt hour and a typical firing takes
> about 10 hours average to reach cone 6 on the ramping schedule I use.
The kiln is rated at 55 amps and 10,555 watts.

If you turned the kiln on high for ten hours it would cost you $7.39.

10,555 watts for 10 hours = 105550 total watts.
105550 divided by 1000 (to convert to kilowatts) = 105.55Kw
$.07 times 105.55Kw = $7.39

Using a watt meter will help you figure it more precisely, but this is the
maximum cost. If you have lower heat settings you can fine tune this
number if you know how many watts the low heat elements draw and the time
you have it on low.

You can use this method for finding out the cost for running any electrical
device. All you need to know is the watts the unit consumes, time on, and
cost per Kw.

So how much does it cost to turn a pot on your electric wheel?

Hope this helps.

Paul

deborah wildenberger on thu 16 sep 99

To figure the firing cost of an electric kiln, you need to know the Voltage
(typically 220), the Amperage (varies), the amount your electric company
charges per KWH (on your electric bill) and the duration of time it takes to
firing the kiln. Basically, the formula goes like this:

1) Voltage times Amps = Watts
2) Watts divided by 1000 = Killiwatts
3) Killiwatts times duration of time = Killiwat Hours
4) Killiwat Hours times your billing rate = Cost of firing

The kiln is not always "on" as it is being firng but this will give you the
highest possible cost of a single firing. The two variable factorsare your
firing time and the electric company's rate.

I figure my small kiln (glaze firing) like this:

1) 220V * 12Amps = 2640W
2) 2640W / 1000 = 2.64KW
3) 2.64KW * 7 hrs. = 18.48KWH
4) 18.48 KWH * 14.924 cents (or $.14924)= $2.76

Hope this helps and doesn't seem confusing.
I usually "space-it" or loose my notes when I need to figure my costs. I
call up a generous "n-gin-ear" friend. He's very patient with me and
explains it all over again.
Feel free to do the same.

Deborah W.
"A Stone's Throw Away"


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David Coggins on thu 16 sep 99

Greg,

My business is repairing and rebuilding electric kilns. Many customers ask
me the same question - "How much to fire my kiln".

I suggest the following formula:- Kiln total kilowatts x cost per
Kilowatthour x total firing time x 60% = total firing cost.

I know it sounds a bit rough, but it seems to work out OK. Based on the
average firing on/off ratio of most kiln control systems. Only fails if you
use the "full power - full blast" technique of some "slip-cast" ceramics
kiln users.

Dave

-----Original Message-----
From: Gregory D Lamont
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, 14 September 1999 5:09
Subject: Calculating firing cost for electric kiln


----------------------------Original message----------------------------
I'm curious to find out what a firing costs in my L&L J-230 kiln (7 cu. ft.
capacity) The kiln is not metered separately from the rest of the house, so
it's difficult for me to tell what the kiln is using by itself.

My electricity costs $.07 per kilowatt hour and a typical firing takes
about 10 hours average to reach cone 6 on the ramping schedule I use. The
kiln is rated at 55 amps and 10,555 watts.

If anyone can tell me how to calculate this or, if anyone has figured out
how much their similar sized electric kiln costs and their electric cost
per kilowatt hour, so I can figure out my cost, I'd appreciate it.
TIA,
Greg
Greg Lamont
gdlamont@iastate.edu
http://www.ourwebpage.net/greglamont/

3011 Northwood Drive
Ames, IA 50010-4750
(515) 233-3442

David Hewitt on fri 17 sep 99

All this is perfectly good advice, but if you could afford to have a
meter fitted I think you would find it worthwhile in the long term. You
may, as I did, find a second hand meter which did not cost much to buy
or have fitted.
I find this to be a very useful addition to seeing what is happening on
each firing.
My electric kiln has two elements, each having a regulator with five
settings which control the amount time on or off for each element.
Theoretically the regulators should be proportional. Setting 1 being on
for 1 fifth of the time and off for 4 fifths of the time. Setting 2
being on for 2 fifths and off for 3 fifths etc. Regulators seem to me to
be notoriously inaccurate and prone to changing as time passes. You can
find that they will be on all the time when only set at say 3. You may,
therefore, be firing faster than you intended. Recording the watts each
time you observe the kiln can help to spot such changes.
Should something fail on one element circuit it is easy to observe this,
not only because the temperature has not risen as expected, but also
because you can see that the meter is not going round at its normal
rate. To find out which circuit can be done turning on only each
regulator in turn.
It is also useful to record the kWh taken for each firing, not only to
help judge if the firing is complete (I use witness cones as the main
guide), but also to see how the elements are wearing. As the elements
get older they take more kWh for the same firing. This helps to judge
when to change elements on cost grounds if they haven't failed on their
own account.
In message , pvw writes
>----------------------------Original message----------------------------
>> My electricity costs $.07 per kilowatt hour and a typical firing takes
>> about 10 hours average to reach cone 6 on the ramping schedule I use.
> The kiln is rated at 55 amps and 10,555 watts.
>
>If you turned the kiln on high for ten hours it would cost you $7.39.
>
>10,555 watts for 10 hours = 105550 total watts.
>105550 divided by 1000 (to convert to kilowatts) = 105.55Kw
>$.07 times 105.55Kw = $7.39
>
>Using a watt meter will help you figure it more precisely, but this is the
>maximum cost. If you have lower heat settings you can fine tune this
>number if you know how many watts the low heat elements draw and the time
>you have it on low.
>
>You can use this method for finding out the cost for running any electrical
>device. All you need to know is the watts the unit consumes, time on, and
>cost per Kw.
>
>So how much does it cost to turn a pot on your electric wheel?
>
>Hope this helps.
>
>Paul
>

--
David Hewitt BSc MIMechE CEng
7, Fairfield Road, Caerleon, Newport, Gwent NP18 3DQ
FAX:- 0870 1617274