We have recently moved into a property that previously had economy 7 (storage heaters and boiler) but the storage heaters have been replaced by simplix fan heaters and tariff changed to single supply when they were removed - but we are having problems with the water heater with is hortsmann E7 - I tried to change timer and now have no hot water when needed -can i reset to previous programme or better still remove and put an emersion heater switch in. Open to suggestions on best solution