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Smarter hot water

TUTORIAL

Use a Raspberry Pi Zero to guarantee you’ll never run out of hot water again

Smarter hot water

e’ve all been there – halfway

through a relaxing shower

and suddenly the hot water

runs out! If you’re not first

into the bathroom, how do you

know if the water will last?

Using a Raspberry Pi Zero and a series of digital

temperature sensors, this project will show you

exactly how much hot water remains in the tank

using a series of coloured LEDs – as the water runs

out, they will gradually change from red to blue. It

will even upload the data to Google Sheets so you

can check the status remotely.

The same technique could be used to monitor

the temperature of almost anything, such as a

greenhouse, a fridge, or a fish tank.

Above

Best of friends –

when all the LEDs

turn blue there’s

no more hot water,

but with a smart

thermostat you

can reheat it from

wherever you are

Jenny Fletch

Jenny is a historian,
administrator and
organiser who
likes it when life is
made simple.

GETTING STARTED

This project is suitable for domestic hot water

systems that use a vented hot water cylinder,

usually installed in an airing cupboard. It will not

work with an unvented pressurised hot water

system. You can tell if the system is vented as

there will also be cold water tank in the loft.

The hot water cylinder is typically made of

copper, and covered in a thick layer of foam to

insulate it and prevent the water cooling down

too quickly.

Hot water is held in the cylinder and heated either

from the central heating boiler or by an electric

element. When you use hot water in the house, it

is taken out from the top of the cylinder and it is

replaced with cold water flowing into the bottom.

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