grant sensor not working

[bmxfrank]

Crivlar set up. The grant between the mash tun and kettle has a probe sensor which tells the grant pump to turn on/off, sending wort to the kettle. Occasionally the senser will fail, and so the pump needs to be turned on/off manually. It seems as if the low/pump off sensor thinks its the high/pump on sensor and either keeps sending liquid although the grant is empty or fill fail completely and drain the grant.

1) has the happened to anyone else?
2) how did you fix it other than replacing the sensor?
3) WHY DOES THIS HAPPEN? What causes it work sometimes and not others? Today it even worked during recirc/vorloff, then quit once going to the kettle.

Frustrating and confusing, not to say not very time efficient. Any advice would be great. Thanks.

Frank

[CaptainEBC]

What type of sensor do you have? Float, optical, conductivity?

What type of control system manages this function? Is it a latch-unlatch relay circuit or do you have any programming?

[BrewinLou]

I occasionally have this prob on my conductivity sensor. Just happened the other day. Two reasons seem to cause it for me.
1. Probes are dirty, a green scrubby usually gets it.
2. During CIP or any other event that the grant over fills a bit of liquid can seep up through the plastic cover into the wire connections outside the grant. I have to unscrew the cap and let the connections air dry.

[bmxfrank]

It is what seems to be what Lou says, conductivity. I doubt its optical as I cannot see/feel anything that would read anything. And its not a float. The probes are connected at the top and that unit goes to the main control panel which is tied to the grant pump. We hose and clean pretty well but I hadnt thought of scrubbing the probes. I'll check with the current brewer and see if that is something he has already done. I just started helping out there and noticed it over the past few days.