What is this?

[uksparks]

Hi,

Customer has moved into a house last year, does not know what this is and neither do i.

It doesn't appear to be anything to do with the immersion, thats just standard, no fans in bathroom or humidity things, no blowers or anything in the loft.

This is outside the bathroom door.

 

[Leesparkykent]

It's a fused spur time switch.

http://uk.farnell.com/timeguard/fst11/time-switch-fused-spur/dp/987037

 

[gutterball]

as above fitted a timeguard one just recently. https://www.tlc-direct.co.uk/Main_Index/Timers_Index/Immersion_Heater_Timers_1/index.html

 

[HandySparks]

...It doesn't appear to be anything to do with the immersion, thats just standard, no fans in bathroom or humidity things, no blowers or anything in the loft.

This is outside the bathroom door.

Heated towel rail or (less likely) underfloor heating?