I designed this module for a friend’s daughter, a student who wanted to be able to turn off her water heater when she was away for several days, as her budget is very tight. For example, if she leaves for a week, she can turn it back on the day before she returns (if the water heater operates during off-peak hours at night) to ensure she has hot water upon arrival.

The water heater accounts for a significant portion of a household’s energy consumption. Even in standby mode, it consumes energy to maintain a constant water temperature. In a vacation home, this energy expense is unnecessary, which is where this setup proves useful. She requested a simple solution that does not require a home automation server. Therefore, I adapted an electronic module that I use to control my alarm system.

My control module allows the water heater to be turned on and off remotely via the Telegram interface. It also sends an acknowledgement message of the command. This setup can also be used for o...