first of all, I am surprised you leave the kiln on when you are not there. I
know lots of people do that, but I wouldn't. You can't fire with kids in
there, but you also don't want a kiln accident to set the school on fire over
night. You need to keep an eye on it.
Maybe try http://www.skuttkilns.com/ for documentation- if the info isn't on
line, there will at least be contact info.