PID not working with a RIMS

[RDH_Texas]

I set up my BCS 460 with a brewers hardware temperature probe, a 1000W 120v heating element in a brewers hardware tube, and to test it out, I ran water through the RIMS tube recirculating it from my HLT.

If I turn the element on manually, use hysteresis or duty cycle, it turns on and off as I expect.
I set the set point to 85F, with 70F water, and the PID does very little. I've tried zeroing out the I and D terms and that does little as well. I get a small spike, and then nothing, or nothing at all.

I've tried in changing the output period, the sample period, no luck.

Can anyone provide some assistance? some settings you use, perhaps?

Thanks,
Bob

[RDH_Texas]

Well, I have had no luck getting this to work.

Here's a test of heating water in the mash tun to a set point of 118

PID_Fail.png (51.37 KiB) Viewed 3062 times

Here's the settings for the PID:

Screen shot 2013-12-14 at 4.01.53 PM.png (81.92 KiB) Viewed 3062 times

Here's the Manual control page showing I was using PID for the RIMS element.

Screen shot 2013-12-14 at 4.24.15 PM.png (59.03 KiB) Viewed 3062 times

Is there any reason it should not be working?
I'm stumped.

Any help would be appreciated.
Bob

[JonW]

From the looks of what you have displayed, you have 3 temp probes setup: RIMS Temp, Mash Tun Temp and RIMS heater. Correct?

Your output setting on OUT2 looks to be associated to RIMS Heater, yet that temp probe never changes from it's temperature of about 98'ish. Something is up there. From the looks of things, you probably want the RIMS Heater output to track to the Mash Tun Temp, but without seeing the names/associations from the setup page, I'm unclear if that is the case.

[RDH_Texas]

JonW, Thanks for replying.

The temp probes I have are:
- RIMS Temp: At the output of the RIMS tube, opposite end of the Tube from the Heater element itself
- Mash tun: The temp probe in the mash tun.

The other two traces are:
- Out2: The state of the RIMS element (0 or 100), corresponding to on or off. It's appear not to be a temperature but a state.
- RIMS Temp set point, the PID set point (118F in this case)

I have a March 809 pump recirculating the liquid from the mash tun through the RIMS element at a constant rate. I never adjusted that during this test.
So when the PID was engaged, it turned on RIMS element and the temp(black trace) started to climb, with the Mash tun temp(gray) following.

I would have expected it to level off as it approached the set point, but it never did. The RIMS element was kept on by the PID.
It's like it' not getting the feedback from the right sensor, but the RIMS temp sensor is Temp3 and that's what I have set as the control sensor for the PID.

When I run OUT2 it in hysteresis mode, the heater element cycles between 0 and 100 as it bangs between the dead-band. It does not turn off for any appreciable time in PID mode. I watched the indication light on the hardware panel and it would turn off only a very short time regardless of the temperature of the RIMS temp sensor, which did not show up on the trace.