Correct wiring of Brewers Hardware Temp Probe to BCS

This might be a pretty basic question, but I was wondering if I have the wiring correct on my temp probe. I seem to be having grounding issues where the temp will read correctly for a few days then all of a sudden go berserk and read orders of magnitude off. (for example, should read 65, but reads 250). On the Brewers Hardware website, the instruction for the BCS temp probes reads:

"Since these are thermistor-based temperature sensors, there is no polarity to the sensor itself. The black and orange wires are used, the red and brown wires are unconnected. The unshielded drain wire is in contact with the temperature probe end but is not electrically tied to ground."

On the sensor that I received from him there are black, red, white, and an unshielded wire. Not the colors indicated in the instructions. I was wondering which color I connect to Temp In and which I connect to Ground. Currently I have the black connected to Temp In and White to ground. It seems to work, but I was still having issues. Do I use the unshielded wire as ground? I test wired it that way and the temp reading was off which means I just might need to recalibrate.

Thanks!!!

I attached two photos of my setup. Not that it has much to do with the temp probe itself. I have the bcs 462 mounted on the wall because eventually I'll have another panel for brewing operations. The two LED lights show if heating or cooling is activated and the LED display shows the set and actual temps. This allows me to see what's going on without pulling it up on my phone. I still need to tidy up the internal wiring.

I had a similar issue and found the wires were shorted out inside a fitting I had installed. once that was corrected, what I thought was a bad sensor was good to go.

The other bissue is make sure all of your grounds are tied together both AC and DC. There is a thread on the BCS site discussing this.

Good luck

I definitely have all of the grounds tied together. That made a huge difference one I tied AC to DC. Everything quieted down.

I'm hoping its not a short somewhere. I am just trying to get a confirmation on which wires from the temp probe are supposed to be connected to temp in and ground.

I'm going on 30 hours of run time now without error...knock on wood =)

So after about three days of run time the temp reading went crazy again...still trying to get a confirmation on the proper wiring of the temp probe in my OP. The BCS temp sensor that I got from Brewers Hardware has a red, black, white, and unshielded wire. Which do I connect to Temp in and which to ground. I am hoping I just have this incorrect.

I think it is just the black an white that you need to connect, thats what I used for mine if I remember. Check for resistance if you have a multimeter. Only one combination of wires should give you a non-infinite resistance, those are the two to connect to the BCS. Polarity shouldn't matter for the connection. I did not ground the probe I am using.

If you did not ground the probe you are using what is your wiring schemaic...i.e. where does the second wire go if not to BCS ground?

My probe is currently set up as

Probe Black -> BCS Temp0
Probe White -> BCS Gnd
Probe Red and Unshielded -> nothing

BentTwigBrew said:

If you did not ground the probe you are using what is your wiring schemaic...i.e. where does the second wire go if not to BCS ground?

My probe is currently set up as

Probe Black -> BCS Temp0
Probe White -> BCS Gnd
Probe Red and Unshielded -> nothing

Click to expand...

Yes the second wire is to ground its been a while since I wired it. Your configuration should work.

hmm so if I have it wired correctly then I wonder what is causing the bad temp readings?

It's the red and white wires you want to use. And Derrin needs to update his site info to match the cable he's using now.

Cool thanks! I will try that tomorrow and see if there is any improvemet.

Well it's definitely not the red wire. When I connect that I get a reading of zero. I connected the white and black and got my normal reading, switched polarity and got the same. So black and white it is.

I just hard wired the temp probe to the bcs, bypassing my control box so let's see if that solves the problem. It will take a day or so for the temps to go crazy again (hopefully not though).

Nice to hear, that means a lack of consistency. Last one I wired was red/white.

Do you think additionally grounding the unshielded wire will have any benefit?

So this was an epic fail...less than 4 hours in the fermentor thermowell the temp reading exponentially increased. At 8am it was reading 456*. Pulled the probe out and went with the JC A419 until I figure this out. I'm ready to throw this thing out the window...

I can't figure out why the resistance changes so dramatically when in the thermowell. It seems to read fine everywhere else except in the thermowell. Could I have a bad probe? I ruled out wiring in my control box as I directly connected the probe to the BCS.

BentTwigBrew said:

So this was an epic fail...less than 4 hours in the fermentor thermowell the temp reading exponentially increased. At 8am it was reading 456*. Pulled the probe out and went with the JC A419 until I figure this out. I'm ready to throw this thing out the window...

I can't figure out why the resistance changes so dramatically when in the thermowell. It seems to read fine everywhere else except in the thermowell. Could I have a bad probe? I ruled out wiring in my control box as I directly connected the probe to the BCS.

Click to expand...

Maybe it is a bi-metal probe and if it is touching the side of the thermowell it gets a change in resistance? IDK... just a shot in the dark there.

The probe is stainless as is the thermowell. I got it from brewers hardware.

http://www.brewershardware.com/Temperature-Sensors/