My friend is too scared to turn on the immersion heater during the day because she is absent minded and only remembers its on a few days later and so gets big bills. She'e on Economy 7, so its set for night time operation but being a small capacity it sometimes runs out of hot water in the afternoon..

Does anyone know of a simple button type switch I could fit for her which could be preset for say 2 hours (ON), so she can hit it (to boost the hot water) and forget it. I've already fitted a red indicator light in the hall but this does not solve the problem.

I've seen similar device for communal lighting but they only work for say 5 mins.