UK Mechanical plug in timer with electric water cylinder on economy 7?

[linuxthefish]

I came across a small electric hot water heater under the sink with a moulded plug in my friend's rented flat. He's on economy 7, and wishes to use a mechanical plug in timer to ensure the water is only heated on night rate. The flat is rented so changing the socket to an FCU is out of the question. Currently he's been switching the cylinder on when he goes to bed, and off when he wakes up and that's been working fine as the sink is only used once or twice per day and it keeps hot all day.

The cylinder is rated 2500 watts, and the timer is rated for 13(1) amps. What does the number 1 in brackets mean on the rating? Is this for inductive loads?

Is there any problem using these mechanical plug in timers at or near their rated current? Has anyone had issues with these timers overheating or catching fire when used with high current loads?

I used to use one of the digital plug in timers with a convector heater, however after a week the relay inside started arching when in use - hence my worry with using a mechanical plug in timer for high loads...

 

[dmxtothemax]

Many of the cheaper ones are flimsy and will not last very long on larger loads.
How ever you can get plug in heavy duty timers, they seem to last much longer