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How to set the clock on a Horstmann Electronic 7 water heater

The clocks went back last night, which means changing the clock on my appliances. One of my few remaining appliances that has a clock but no Internet connection is the timer on my boiler. It’s a new boiler (I moved in June), so I’ve never had to set the clock on it before.

It turns out it selected the correct winter/summer setting itself, but it’s drifted by twenty minutes, so I decided to set it anyway.

This is the timer on my boiler:

A control panel with some white, green and blue buttons and a small, poorly-illuminated segment display reading “10:10”.
My boiler is in a utility cupboard next to my front door. When I turn on the hot water boost, I put the post-it note on the cupboard door, so I don’t leave it on when I go out.

The name on the bottom right says “Horstmann Electronic 7”, so I did the obvious thing and googled “set clock horstmann electronic 7 boiler”.

It took me several minutes to find the answer – in the user guide for the timer – so for the sake of future!me and other Googlers, here are the instructions for setting the clock. Unless you have this exact appliance, you can stop reading.

This is a diagram showing the front of the timer:

A control panel with white, green and blue buttons and a small segment display reading “03:04”.

To set the clock:

  1. Press the green “SET” button until the left-hand indicator points to “CLOCK”. The hour should start to flash.

  2. Adjust the hour with the “MINUS”/”PLUS” buttons. It wraps around for AM/PM as appropriate.

  3. Press the blue “SELECT” button to confirm the hour. The minute should now start to flash.

  4. Adjust the minute with the “MINUS/PLUS” buttons. It wraps from 60 to 0 and vice versa.

  5. Press the blue “SELECT” button a second time to confirm the minute, and to finish.