Complected name for a thermostat?
A thermostat is a switch. Above a set temp, it turns off. Below set temp, it turns on. There is generally some hysteresis due to mechanics but not always.
A PID allows for much more precise control.
I started trying to control temps on a smoker using an electric fan thermostat and a solenoid. It does work, go over temp the the thermostat triggers the solenoid closing off all air flow, lowering the temp until it drops below the set point and opens back up. It over shoots and lags behind to catch up but the setup would maintain within 5 degrees F, pretty much like a house hold oven, except that’s also how you make smoke signals. Letting a fire “go” then cutting it off turns everything black with smoke, unless you wrap it early.
With a PID you can set the parameters in a way where if it’s close to the set point it makes tiny incremental changes to get “right on”. If it sees a huge drop in temp, like you open the food door, it will open the damper dramatically. Then once you close the door, it recognizes that the temp is rapidly increasing and will start closing the damper to keep it from overshooting the set point. Same goes for the opposite if the fire door is opened.
On a calm day, a PID can keep a mature wood fire stable inside a single degree F.
When it’s that close it may only activate the damper for a tenth of a second, barely even turning the 1/4-28 stainless rod that moves the damper. Precision you just can’t get with an on/off device.
So now I need to get my PID hooked up for my pot and a separate probe for my oven. Hope someone can learn from my mistakes
