Temperature Sensor on Heat Exchanger

Thread Starter

geofreyr

Joined Jul 25, 2017
6
Hello,

I have a heat exchanger which has a wire connected to it which is merely drilled into the lead casing and connects to a PCB board into two sockets, + and -.

The heat exchanger also has a temperature switch to detect the thermal temerature and activate and deactivate accordingly.

I don't understand what the purpose of this other wire is and how it works. Please see the attached image showing the wire.

Many thanks,

Geofrey.
 

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Thread Starter

geofreyr

Joined Jul 25, 2017
6
I think it's actually called thermocouple wire. But how does it actually detect the temperature because it does not seem to have a thermometer?
 

Thread Starter

geofreyr

Joined Jul 25, 2017
6
As you can see, it simply screws onto the top of the heat exchanger. I am reading about thermocouple wires work now actually, I think that is what it is, using thermal electricity to determine the heat exchanger's temperature? thanks.
 

BR-549

Joined Sep 22, 2013
4,928
Ok.....the red and blue wires.....are dissimilar. They are connected at the circular terminal....under the shield. When that dissimilar junction heats up....it cause a small current and voltage differential at the junction. This voltage is proportional to the temp. Connect a volt meter to the wires.....and hold circular terminal over flame. Watch the voltage go up.
 

Dodgydave

Joined Jun 22, 2012
11,285
Connect a Voltmeter on Millivolts, and hold the Eye terminal in a flame, the red and blue wires will give out a DC supply as the temperature rises, probably 2- 100 mV.
 

Thread Starter

geofreyr

Joined Jul 25, 2017
6
Why does it have both a thermocouple wire and a thermometer switch, would this be used as a safety precaution in case the switch fails the thermocouple has been programmed on the PCB to turn off the power?
 
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