Electric shower question

I have to agree...we have an electric shower (everything in our flat is electric) and we never have our hot water heater switched on as the shower makes its own hot water.

Our shower makes a humming sound when the water pressure is low.

That sounds like mine. I never turn on the hot water heater when I'm using the shower. The shower makes the water hot on its own.

Do you live in a hard water area? You'll need to clean your showerhead of limescale every couple weeks, as it builds up pretty quickly and when it does the shower will strain.