I am building the conduit spaghetti monster mess for the temperature sensors on my fermenters and also the sensors for the boil kettle and liquor tank. I have heard that they run at closo to zero voltage so should be isolated from the solenoid power lines and other power lines etc.....does this mean they should be further sheilded by grey PVC? or is metal conduit OK for these sensors?
also is the dollar/ft wire from the brewery supply guys the way to go or can I use 18 gauge thermostat wire from lowes? (it seems to match perfectly with the old stuff)
our state agent has been out, and said "call me when you make beer" but we just arent quite there yet....so close!
Low voltage lines (sensors) should be run separate from high voltage lines (solenoids).
Metal conduit is fine. I suggest rain tight fittings just to be safe. You should check with the control manufacturer to see if shielded wire is reccomeded and the wire size that should be used for the sensors.
I've used less expensive but identical wire without problems in pvc. It may help to add a ground wire in the conduit (if plastic) and only ground the tsat end-not the sensor end nor both. So I've been told.
On the fermenter thermometers there are two wires coming out of the sensor. The + side of the wire is copper, the - side seems to be a copper/nickel alloy.
How important is this alloy in measuring temps properly?
Why not just use copper on both sides?
And finally, where can I get the stuff cheap if it's a must have item?...JVNW sell the stuff for a buck a foot.
Just went through a bunch of this stuff myself, so here's what I've learned:
1. Some say that running separate conduit for thermocouple wire and solenoid wire is required, but some "pros" say otherwise. I have also read that twisting the thermocouple wire pair can help isolate it from the 120v (or 24v or 250v or whatever volt) solenoid.
2. A thermocouple (or TC) is made by soldering/joining 2 wires together made of different materials. The dis-similar metals povide a resistance that varies w/ temperature, and your controller knows how to read this.
The materials used determine the thermocouple "type", as in J, K, L... The color of the wires you are planning to use will give you a clue as to the type of TC you have. I have some blue, some black, but I can't recall offhand what the types are.
When you attach the wire pair to the TC, and run it to the controller, you are in effect extending the thermocouple itself. If you use any ol' wire pair as I have done, you won't get squat for a reading. Same thing if you reverse the leads. Reason is, the connection to the new material provides an offset to the original difference, cancelling it out. Thermostat wire is NOT TC wire, and again, the wire needs to match your TC "type".
Try McMasterCarr as a source for the wire. Best price I could find, and the rep on the phone and the section in their catalog were quite educational.
We just did our very first batch here. Those last weeks are the longest.
Mcmaster-Carr or Grainger are going to charge too much for type j thermocouple wire. Look up your local process control or instrument companies. Loy Instrument in the Indiana (Indy, Cleveland, Toledo, Ft. Wayne) sells the stuff for .23 a foot.
great, thanks alot guys. Just found a place in town selling it for 33 cents/ft. It is easier to find what your are looking for when you know what its called....
- something I left off of my post: I ran my TC wires in the same conduit as the solenoid wires and have had no problems with readings. They exactly match the dial thermometer in the thermowell. Run is about 30 feet.
Thanks everyone for the answers...turns out I needed type "T" wire for the thermocouples (i thought they were RTD's....geez)
Anyway everything is wired up and today i flipped the breaker, and each of 6 themometers registered within a degree of each other right inline with the themo on the wall. Now I have to figure out the buttons on the control panel (labeled mysteriously with letters only "V" "C" "P" and others...) to make the solenoids work.
so thank you everyone and cheers to probrewer!