nead i say this? yes you'll be suprised how many forget when its too late then gripe about the cost of replacing the water heater tank.

drain down all units containing water.
eithr cover the vent of the carver water heater with a plastic bag containing fibre insulaton or box it with polystyrene this can be held in place using kebab stick peirce the pollystyrene so sticks go through behind the vent to hold the boxing in place.fill and gaps

if you can't open the external drain plug on the carver heater cover the tank with a blanket even if its still got its polystyrene jacket. it cost more than time and pence to replace if any tanks freeze and split. and don't think about anti-freeze even in the toilet tank which is inside. cassette tank should be stored in the carvan not left in the locker, i never leav mine in the locker during winter..

BOB, November 2010