Can someone help me "fine" tune my pid controller? I built my own smokehouse, approx dimensions are 5feet tall by 3 feet wide and 3 feet deep. I use a Bradley smoke generator and an Auber dual probe pid controller. First problem I encountered was getting enough heat to bring my cabinet up to temp fast enough. The controller in 120volt input only will give 120 volt output which will not give enough watts to supply the heat needed. I cannot run the controller at 220volts as the bradley smoke generator will not handle that voltage. So.... I used a specific purpose contactor which the controller supplies the coil voltage of 120 and when the controller senses it needs more heat, it closes the electro mangnetic switch to my 220 volt supply for 3 electric elements in the cabinet. This is working quite well with only one negative. The controller wants to decrease the output as the cabinet temp gets closer to target temp. This tends to cycle my electro magnetic switch every 2-5 seconds. I've played around with the parameters and have it where it will only cycle that fast as it comes up to temp, once the cabinet reaches target temp, as it overshoots by about 5 degrees, it will cycle at a reasonable rate. I did try autotune first and wasn't happy with those results. Ideally, what I want is the following steps.
1. cabinet temp 120, smoke on for 2 hours
2. cabinet temp 135, product temp 110
3. cabinet temp 155, product temp 125
4. cabinet temp 185, product temp 155
5. cabinet temp 130, hold 3 hours.
So my Pid should really only be on, or off, temp variance can be as much as plus or minus 5 degrees. Any thoughts?