Temperature from probe jumps

[hoofheartedbrewing]

I bought the BCS-462 from http://www.brewershardware.com/ and they were out of the 8" probes so I ordered 4" probes. The temp reading I am getting jumps around by 7 deg. F. So even when the glycol chiller is off, it will say the temp is 58 deg and then travel down to 53 deg and back up, all within the span of a minute. This is a 7 BBL fermenter so there is no way the temp is drifting in the tank like that. Any ideas?

[SamIam]

Did you cut or add any wire to the probe? Also, make sure that you run an AC ground lead to one of the BCS ground posts. This post describes a similar issue. http://forum.embeddedcontrolconcepts.co ... 5985#p6908

[hoofheartedbrewing]

Sorry for the late reply. I guess I should have read the MFG website more carefully because they say something very similar there. Connecting the DC ground to the AC ground absolutely solved the issue!

I would like to note for other users of this product that I even tried shielded cable to extend the length of the probes making sure to connect the shield between the cables and grounding the shield but I still got noise. I was even getting noise on a probe that was not extended though it was much fainter. Once I connected the DC ground and AC ground together, the noise went away and has not caused issues since.

Thanks,
Ryan