It's an electric water heater. I'll get out there with a screwdriver tomorrow when the daylight's at its peak (it's in the back of the garage) and try turning it down. Or I'll get Dave to if there's enough garage light tonight or when he gets home tomorrow.

So if the hot water heater's going and it's been giving us hotter water and not rinsing as efficiently, maybe a new hot water heater might solve the problem? Is there anything I can do to help de-film the dishwasher now? Pour some vinegar in when it's about to rinse?