Crazy boiling after reaching setpoint

[estricklin]

That pid cannot not have manual mode because it would require the mechanical relay to turn on and off so quickly it would burn up in a short period of time... Therefore there is likely a minimum cycle time set that is making the element stay on for longer "cycle" times to protect the relay and prevent it from over heating... this would cause your over boiling issue..

like others have said you need a pid designed to drive an SSR and with manual pwm mode.

As Bobby suggested the mypin td4 snr is a great fit.. its what I use with no issues. you can ditch the 24v supply then too or use it to power a cooling fan for the ssr and some 24v dc 3gpm food grade pumps like these if you dont already have pumps
http://www.ebay.com/itm/251768710886?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
that I use in my setup below

He could also use that 24v DC power supply with the switch he has, to power a relay for the AC wires before they reach the SSR, so that there will be a quick and easy way to kill the power to the heating element in an emergency.

 

[augiedoggy]

He could also use that 24v DC power supply with the switch he has, to power a relay for the AC wires before they reach the SSR, so that there will be a quick and easy way to kill the power to the heating element in an emergency.

yes I do that as well with 25a omrom relays instead of the bigger contactors.

 

[jsbird]

My guess is that your controller is configured to vary the voltage of the signal going the SSR (you described as controlling the "gain"). Therefore, if you set it at 50%, then it sends 50% of the voltage to SSR which would not be enough to switch it off. The duty cycle of your SSR needs to vary the on/off time of the signal going to the SSR, not vary the voltage going to the SSR which would be relay mode. An earlier commenter asked if the SSR LED was cycling on/off when you were in duty cycle mode. If it stays on, then that would support this theory. Measuring the output of the controller when a multimeter while it is cycling would confirm it. That controller does appear to support relay/SSR mode. As I understand it from looking at the Love controller documentation, you set the mode by removing the controller from it's housing and moving the jumper from Output A to Output B. Google for the documentation and look in the Logic Jumper Selection section.

 

[foy1der]

My guess is that your controller is configured to vary the voltage of the signal going the SSR (you described as controlling the "gain"). Therefore, if you set it at 50%, then it sends 50% of the voltage to SSR which would not be enough to switch it off. The duty cycle of your SSR needs to vary the on/off time of the signal going to the SSR, not vary the voltage going to the SSR which would be relay mode. An earlier commenter asked if the SSR LED was cycling on/off when you were in duty cycle mode. If it stays on, then that would support this theory. Measuring the output of the controller when a multimeter while it is cycling would confirm it. That controller does appear to support relay/SSR mode. As I understand it from looking at the Love controller documentation, you set the mode by removing the controller from it's housing and moving the jumper from Output A to Output B. Google for the documentation and look in the Logic Jumper Selection section.

The PID has no jumpers, you must be looking at the wrong manual. The LED does cycle when in duty cycle mode. I haven't had time to play with it recently to measure the voltage across the SSR during duty cycle mode. But the point might be moot because I bought a TD4.