I recently moved into a new house with an antique central heating system and immersion heater - looking to replace in the new yeat! My problem at the moment is whats the most cost efficient way to heat water??? Do i leave the immersion switched on all the time or just over night? I think its a direct cylinder (square tank) and there's no timer. would appreciate any advice. thanks
Thanks Martin, the meter is two rate and there is no boost control - honestly it's that old. I'm manually switching it on at 11pm and turning it off at 7am, is this the best way to temporally deal with this as the whole system is going to be replaced in spring 08?
It is quite an easy task to feed the immersion element via a power socket, fitted in place of the present wired outlet. There are many brands of socket-top timers ( eg the simple Smiths unit I used to use to power the washing machine during the cheap E7 period ). These have synchronous-motor clock drives, with pegs to set the "ON" periods, and a manual override on the side. There are electronic equivalents.
Switching on the immersion at 11pm is I am afraid the worst thing you can do. Economy 7 is between 1am and 8am, and those two hours between 11pm and 1am at standard rate are just about the length of time it takes to heat the water.
If you intend to replace the heating next year, it seems pointless to have a timer fitted as the installation costs involved will be more than the savings.
So if you can't manage to switch on after 1am or before say 6 or 7am, I would suggest leaving it on 24hrs.