I absolutely love One-Wire sensors and have made liberal use of them in my bus.

A One-Wire device communicates via a single signal pin and can work up to 200ft with twisted pair wiring. So just three wires to handle signal, power and ground that works as a distributed electrical sensor bus.

Here's how they are hooked up to my Raspberry Pi controller for the bus:



Another value point is that they are less than $3.00 a sensor for general use and around $20.00 for the inline liquid temperature sensing.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Note for the liquid sensor you want the 30mm version to use on a 1/2 pipe tee.

Each sensor has a unique ID that must be determined by adding one sensor at time and determining which id is the new one.

Here's the twelve sensors that I currently have installed in my bus.

//
// One Wire Id's DS18b20 Temperature Sensor
//
4D18940B0000 Hydronic output
1B6EE10B0000 Diesel boiler output
AA8B11481401 Generator Bay
AA35AF481401 Fresh Water Tank
AAF6A0481401 Forward Bay
AAC09E481401 Mid Bay
AA01BF471401 Battery Bay
AAE595481401 Plumbing Bay
F854950B0000 Engine Coolant (heater hose input to Glycol Heater/Tank 2)
AA9EA9481401 Under bus outside air temperature
AAF58F471401 Refrigerator
AAA09A481401 Freezer

This makes it very easy to monitor/alarm or automate desired functionality.