Originally Posted by lschiavo
I would consider building a pulse width modulator controller instead of a pid. Boil controll really does not need temp feedback and a pwm will save you from an extra hole in your kettle for the probe. Plus I found it to be quite a bit cheaper.
If you want to keep it simple and don't know electronics a PID is still a reasonable way to go to control the boil in the boil kettle.
No need to put a hole in the kettle for the boil temp probe either, it doesn't have to be in the kettle at all. In fact, you don't need to use a temp probe at all. Just use a fixed 1 cent resistor.
I considered building a PWM circuit instead of using a PID for my setup to control the boil, but once you factor in the parts including a waterproof control, the price difference is negligible. Not to mention the extra work to save maybe $10-20.
There are other advantages too to actually putting the temp probe in the boil kettle: You can set the PID to 208F and never have unattented boil overs. It'll simply ramp up to just before boiling, an alarm can be set to go off then and then you go into manual mode and watch for boil overs.