Shower Temperature Sensor

I'm sure the first question that comes to mind is "why do you need to measure the temperature of your shower?", which is perfectly fair.

Now, to be sure - I do love to measure anything I possibly can, but in this case I didn't so much care what the temperature of the shower was, rather I needed a fast and reliable way to determine if the shower was in use or not. There are definitely more straightforward ways to achieve this, but none of these options really worked for me:

Flow sensor: The best option, but would require cutting open walls to install it.

Motion sensor: Difficult to limit the field of view to just the shower and not the rest of the bathroom.

Humidity sensor: Workable, but slower.

In the end, I used a 10k thermistor attached to the pipe with thermally-conductive epoxy. The cable was fished back up through the attic, so with the cover flange back in place the sensor is completely hidden, leaving a clean appearance.

With the BAS knowing whether the shower is in use or not, it's able to:

  • Automatically turn on the bathroom fan

  • Extend the time-out of the motion sensor lights in the bathroom so that they don't turn off whilst in the shower

  • Turn off the hot water re-circulation pump to maintain a consistent temperature