Box wired to domestic water pump

[Lucy52]

Hi, While investigating my empty water tank. I came across this black box wired to the pump. It appears to have a white adjustable knob on top. I could play with it to see what happens but as I don't know what it does and it might not have any immediate effect I thought to ask here if anyone could shed some light on what it might do.

 

[pvb]

It looks suspiciously like some sort of thermostat - is that a thin metal tube going in to it near the wiring?

 

[Lucy52]

Pete you are right, thank you. I have just untangled the wires and it isn't connected to the pump at all, it must be for the fridge.
I hate marine electricians, bundles of wires all neatly bound up in corrugated conduit, threaded round and through inaccessible dark places without a single label. They all look the same, you have to pull them all apart to find the one wire you are looking for.

 

[tillergirl]

That is the Thermostat used for my Waeco evaporator plate.