I'm from England tolterodine (detrol la) 2mg 24hr capsule Regarding water heating, there is no one “system” more efficient than another. The immersion heater will switch on automatically during the off-peak charging period, and how long the hot-water cylinder retains its heat throughout the following day will depend solely on the quality of insulation surrounding it. Modern cylinders are factory-coated with foam, but I don’t think it would be worth scrapping your existing cylinder to fit a new one – you might just as well fit an extra insulating jacket to it.