Thank you. Confusing that something related to heating is right by the hot water tank, so I assumed related to that. When I've done that before (Black lever) I usually end up with overflow water out of a pipe outside by the front door, even if I only top it up to the bottom of the ideal range...
Hopefully my photos are attached. My boiler pressure is always low (see boiler photo), despite having my boiler serviced recently. There's also a pressure gauge above my Megaflo hot water tank. I've been told by different people that they are the same reading in two different places, or that one...
Our holiday home apartment has a Horstmann Electronic 7 timer to control the hot water with a PulsaCoil A-Class hot water tank.
There is obviously more than one make of the timer. Our version appears to allow only one off & on time rather than three, as described in the user guide I found...