Installing three zone controller on your kiln

Dear fellow potters,

I just purchased and installed a three zone controller for my kiln. I
would like to warn anyone who is considering doing this.

I am generally satisfied with the controller itself, and the company
provided me with responsive and competent technical support. But they
did not guide me in determining whther my kiln would be sufficiently
powerful enough, and I am disappointerd with this.

So here is my advise. There is one major thing that you must consider
before retrofitting a 3-zone controller to your kiln. Your kiln must
have considerable surplus power to reach your highest working cone. And
I do mean considerable.

Here's why. When you run your kiln manually, and let's say your reach
your cone in the last half hour at a rate of 108 DegF\Hr. Then,
assuming that you are running at full capacity to achieve this, then
you will certainly not be able to maintain this same rate with the kiln
controller. The controller will be switching your elements on and off
as it tries to maintain even heat, so only a percentage of your kiln's
capacity will be used. Consequently, it will not be able to maintain
your intended rate of heating and may not even be able to reach your
cone.

I am not an expert, so I can't give you any kind of formula to use for
determining this. However, it would seem that if you can reach your
cone reasonably by running at, say, only two-thirds of your full power
(such as running with only 4 elemnts out of 6 total), then it might
work out okay.

If not, you'll still be able to run your kiln unattended, but you will
not be able to get uniformly heated zones at the end of your fire.