Installing temperature sensors

Updated 9 October 2026Fluidy

You can connect up to 5 temperature sensors to Fluidy Pro. They all share one common line, and this may be no more than 3m long in total. The sensors are available separately. They have a blue, food-safe silicone cable and measure accurately to ±0.5°C.

Connecting to the plug

Each sensor has three wires that go into the 3-pin plug:

  • Red to pin 1, the power supply
  • Yellow to pin 2, the measuring signal
  • Black to pin 3, minus (GND)

How to wire several sensors

The most reliable way is this: run a short cable from the plug to a distribution point near the sensors, for example a small terminal block. The individual sensors branch off from there. This holds better than clamping all five cables directly into the pins of the plug.

Important: stay under 3m of cable length in total. And work neatly: because all sensors are on the same line, a single bad solder joint takes all the sensors out.

Where the sensors make sense

  • Fresh water tank: if the water temperature heads towards 0°C, the tank heater switches on automatically.
  • Boiler: you see the water temperature live and set a target temperature on the SmartKnob.
  • Heating return or interior: this lets you see how well your diesel heater is working.
  • Fridge compartment or outside air: helps with troubleshooting and is simply handy on your travels.

Related questions

What does Fluidy measure?

Fluidy Pro keeps an eye on all the water in your camper: • levels of up to 4 tanks, for example fresh, grey and black water • up to 5 temperatures, for example at the boiler, in the heating circuit or at the fresh water tank • the pressure in the water line • leaks via the leak cable For smaller builds there is Fluidy, more compact and more affordable. Both fit into the same system. More on this in [Tank levels, temperatures, pressure: what Fluidy Pro measures](/blogs/wissen/tankfuellstaende-temperaturen-druck-was-fluidy-pro-misst).

Are the sensors included with Fluidy?

No, Fluidy deliberately comes without sensors, so you only pay for what you really need. Level sensors, temperature sensors, the water pressure sensor and the leak cable are available from us individually. The matching connectors come with each sensor.

How accurately does Fluidy measure the tank level?

Typically to within 1%, relative to the full measuring range. The sensor hangs in the tank and measures how strongly the water presses on it at the bottom. That tells you how full the tank is. Floats or three-stage probes, by contrast, usually only tell you that things will get tight at some point. The calibration in the dashboard guides you step by step, no maths needed.

Can I back up my tank calibration?

Yes. At the very bottom of the tank settings you export the calibration. If you ever delete the tank widget or create it again, you load it back in completely via "Load profile". Best to back it up right after calibrating. Converters use the same calibration for the next vehicle this way.

Does the level sensor work in every tank?

Installation is the same for fresh, grey and black water tanks. The sensor also measures perfectly in stainless steel tanks, because it hangs inside the tank and does not have to measure through the tank wall. You need a 17mm hole at the top or side of the tank, close to an inspection opening. The watertight cable gland is included. Step by step in [Installing the water level sensor](/blogs/wissen/wasserstandssensor-einbauen).

What do I need to watch out for in frost?

Level sensors and the water pressure sensor must be completely free of water whenever there is a risk of frost. If water freezes inside a sensor, it is permanently damaged. So when you winterise, drain the tanks and empty the fresh water system, ideally draining the pressure sensor via the drain tap.

Can I keep using leak detection cables from other manufacturers?

Yes, they can be connected, but we have not tested this. The two contacts of the cable go to + and S on the leak port, polarity does not matter. Our own leak cable is tested for durability and detection. With third-party cables we do not know the coating or construction, so we cannot guarantee that a leak will be detected reliably, now or in a few years.

How does Fluidy detect a leak?

With a 3m leak cable that you lay flat wherever a leak would show up first: under the pump and boiler, along the water installation, at the water filter. As soon as the cable gets wet anywhere, the SmartKnob raises an alarm. With the leak widget, the water pump switches off as well when the alarm goes off. To cover more area, simply connect several leak cables in parallel to the leak port. More on this in [Detecting water leaks: how the leak cable works](/blogs/wissen/erkennung-von-wasser-leckagen-so-funktioniert-das-leckagekabel).

Can I connect several leak cables to one Fluidy?

Yes. Join the cables in parallel, for example with WAGO terminals, and run them to Fluidy with a two-core cable.

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