That's why I've just gone over to the l5 heater. I transfer the water I need cold and then circulate it thru the heater. And I only take what I need. No point heating water your not going to use, but I had the element in the top of the tank so therefor had to heat the full 1000 liters. In all honesty though I don't think it loses a lot of heat on transfer, water has an ability to retain it's own heat. Even at the end of the day the temperature of the water would still be warm.
Simon.