Hacking a hot water system for home automation

This is a video I did almost a year ago but it’s kinda relevant to Practical Arduino so I thought I’d post it here. My house has a Rinnai Infinity tankless hot water service that heats water to a specified temperature as it flows through the pipes rather than pre-heating it and storing it in a tank. The Rinnai system uses keypads in appropriate places such as the bathroom and kitchen so you can dial up the temperature you want and know it’ll come out of the tap at that exact temperature.

I wanted to automate the process more though so I could do things like walk into the bathroom to have a shower and have the home automation system:

  • Turn on the lights
  • Close the windows
  • Close the curtains
  • Turn on the exhaust fan
  • Pre-set the water temperature

all in one go automatically.

So I hacked a Rinnai controller to link it to an Arduino.

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