Hi, Ross

I do not exactly know the 'professionnal level" you want to build your control, but, what exists :

1) the programmable temp regulator ... I used it to control Cast iron heat treatments. costs some $$$ ... but most reliable !!!

2) The "el chapo" device ... have a look to Parallax "industrial applications" booklet ... there's how to realize a simple PID temp regulator ( w/soft offered !!! ) . an AD595 or MAX 6675 will be a good interfacing to Thermocouple.

With Darrel's instant interrupts, il wil be easy to drive the system clock , now.

On this basis, I've realized a vent regulator to control with a R/C servo the cowling apertures for a model plane engine ...

Here, I output the command signal @ 40 Hz ... so it might be much enough for your application !!!

Alain