Dave Finkelnburg on sun 2 nov 03
Stephani,
It is always sad to hear of a good kiln gone bad. :-( These things
happen, though...even in the finest families! :-)
You ask about electric kiln amp ratings. First, think about the loaded
kiln like it is a box in space. Power goes in as heat. The heat
accumulates in the ware, shelves and posts, and kiln, and heat also leaks
out.
IF you have two kilns of exactly the same internal dimensions, and one
has a higher amp rating, then you can say certain things about the two
kilns. As you note, the higher amp kiln will heat faster IF both kilns are
similarly insulated. The better insulated kiln will lose less heat so it
will take less power to fire.
Kilns can difficult to compare. If two kilns have the same internal
volume then it's easy. However, if you have two kilns that look about the
same size, but one has 2.5-inch thick insulating brick walls and the other
4.5-inch thick IFB walls, the second will use less power because it has more
insulation AND less volume for stacking ware!
I think the best way to compare kilns is to make some common-sense
ratios. Divide the amp rating by the internal volume for example, so you
have amps/cubic foot or cubic meter. For kilns with the same wall thickness
or similar insulation, this will give you an idea of which kiln has extra
power or is deficient in power.
It's important to keep in mind that not all kilns are created equal.
Quality of elements, switches, lid hinges, etc, etc, plus service, affect
price and are very important but not easy for us potters to compare.
Finally, extra insulation is good value for the money with kilns. Your
example, rebuilding a 31-year old kiln, is an indication of how very long
good kilns can last. Saving pennies on brick or fiber today will cost
dollars in power every year for the life of the kiln!
I hope the rebuild goes quickly and works well for you.
Dave Finkelnburg, anticipating snow again tomorrow in Idaho
----- Original Message -----
From: "Stephani Stephenson"
To:
....> one thing which really intrigued me as I was checking out
> new kilns was that , in general the larger 'studio' model
> electric kilns we are all use to , the octagons, etc. really
> draw a lot more Amps.... some of them require 70, 80,90 amp
> breakers....This big old behemoth kiln of mine draws much
> less...38 amps, (I have a 50 amp breaker.).. so I wonder why
> this is? Right now I am not remembering very much of my
> electricity 101 so can someone tell me does this translate
> into higher power usage per unit of time when the kiln is
> on full power for example?
> when one compares a kiln drawing 80 amps v. one drawing 50 ,
> for example????
> So what in the kiln or element design calls for the
> increased AMPs needed on these newer models?...my old Skutt
> 1027 needed a 60 amp.... but I don't recall seeing 70,80,90
> .....
> Is it just that the super insulation allows the kiln to fire
> less (by switching on and off during heat rise) and thus
> draw less?
| |
|
