I now live in a house with an electric water heater that warms the temperature on the fly to the temperature we set on the display, provided it’s not too cold. But in the past, I lived in colder climates with water pre-heated in a hot water tank, and accessible from most taps in the house. Each time I took a shower I had to adjust the cold and hot water taps, wait a bit and do further adjustments to get the right temperature, not too cold, not too hot.
I’ve just come across a little gadget that you ease this process as it displays the water temperature on an LCD display. The installation looks fairly easy, and there’s no need for batteries as it’s self-powered with the flow of water. 
Some of the key features of the device include:
- Display – 360-degrees rotatable & waterproof LED display design: and waterproof design for better viewing
- Sensor – High-precision temperature sensor with 0 to 100°C range, 0.5°C accuracy
- Power – No batteries required: the device harvests its energy from the water flow
- Dimensions – 8.10 x 8.06 x 3.00 cm; screw nut size: 1/2 inch
- Weight – 160 grams
- Materials: ABS, PC
None of the sites I’ve checked clearly mention how energy harvesting works here, but I assume water may make a small wheel turn to generate enough electricity to display the temperature on the LCD.
The device can be purchased on Banggood, but you’ll also find it on Amazon
Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.
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In my country, any shower built in the last 20 years, will have a “thermostat tap / faucet”, and it will always give you automatically the temperature you want.
Yes, we have those good old mind reader taps here too…
@L.Peter
Which country out of curiosity? Us UK folk are a bit backwards when it comes to plumbing, mixer taps still aren’t everywhere, let alone ones with accurate temperature dials (my shower is set to 80C which should melt my flesh). Unfortunately I can’t think of a way to fit one of these to my shower.
Buying. Thanks 😀
@CampGareth
Reading your comment made me remember a video by Tom Scott about this: https://youtu.be/HfHgUu_8KgA
I have purchased many of these, usually just to replace the defective ones. There is no supported warranty on these at all. Good luck finding any that display F. These are very cheaply made devices from an untraceable Chinese manufacturer. These devices are a very good example of Cheap Chinese Junk, unloaded on the market.
Wow! And I was just about to ask how affected these were to hard water & if they could be treated in vinegar? Thx for the heads up.