Economy 7 Immersion Heater

[BPM]

I have a twin element immersion heater. My problem is I don't want the Economy 7 element on all night - ie 12.00 midnight til 7am. I only want it on for approx 3 hours a night. HOWEVER a standard time switch isn't suitable because of course power is only flowing down the cable for this 7 hour period and the clock needs to be powered 24/7 to maintain the correct time. What is the solution ?Are there such things as battery powered time switches ?

Thanks /Brian

[gerdy]

I had the same problem, although the thermostat setting will not allow the element to be 'live' for the whole time. Try setting your thermostat to about 60c first and see if that works. An extra thick tank jacket will help. it worked for me. 

[Dave Barton]

I also have an emmersion heater that is powered by cheap night rate electricity ( economy 7 ) but this is wired into a 15 amp MCB at my standard Consumer unit so the power is supplied 24/7 via HORSTMANN timer but my storage heaters are powered via a timer at the con unit and i have the same problem as you as i would like to boost them at 6pm I think the solution is to dispense with the REB  timer