I previously purchased some clip-on pipe sensors to monitor heating of water travelling in the copper pipe. Could I use these with emonTX? If so what would I need to do? The sensors came from Rapid - ATC Semitec 103FT-7Y045 20-22mm IP67 Rated Pipe-Clip Temperature Sensor | Rapid Online
That appears to be a NTC thermistor. What you need to do is measure its resistance, then use a lookup table and maths to convert that resistance into a temperature.
So the problem becomes one of how to measure the resistance. You would need to connect it across the supply in series with either another resistor (much like the light sensor in the GLCD) or via a constant current source, then you would need to use ADC 5 (presently used as a digital output to power the DS18B20) to measure the voltage across the sensor. It’s that voltage which would convert to a temperature via the look-up table. Of course, unless you heavily modify (i.e. for the most part destroy) one or more current inputs of the emonTx, or you add a multiplexer (see Building Blocks and Pt1000 temperature sensing, you can have only one sensor.
It can be done, but requires quite a lot of development work.
Thanks for the detailed response Robert, sounds like too much work and development for me