Kris

There are cheap temperature controllers in ebay which can switch on/off based on a temperature preset as suggested by SubzeroLT. As a sample, pls check the link below. http://www.ebay.com/itm/50-110-C-W1209-Digital-Thermostat-Temperature-Control-Switch-Sensor-Module-12V-/182071212734?hash=item2a644a3abe:g:-1UAAOSw2zlXhIWb There are many such things in ebay. It needs a bit of DIY to connect buzzer for alarm or to on/off certain equipment when reaching the temperature preset. I am using this in my Pico to switch on/off the cooling fan on reaching certain temperature. I know that the probe is stainless steel and will corrode over a period of time. So far, i didn't see adverse effects with carbon running in.

$ 10

$ 23