by ericmark »
Sat Oct 29, 2016 11:00 pm
The top switch is called a fused connection unit and is most likely the supply to immersion heater, the next is a simple switch and I have really no idea what it might be for, the next box is likely the connection to central heating and the unit held to the tank is likely the sensor for the central heating so it knows when to heat the hot water.
Domestic most switches go down for on, not domestic is the reverse so anything falling on a switch will switch it off not on.
The immersion heater should have a thermostat built in, and also a cut out, if the tank is thermal plastic it should be non resetable but if the tank is hard plastic or steel then a resetable type can be used.
The thermostat in the immersion heater should be set above 66 degs C but less than the central heating so it will only cut in if central heating is not running.