For UK users and other cold countries.
Cascade water heaters ensure it drained for winter. Put extra insulation around the tank the polystyrene jacket is not for stopping freezing. Get a roll of loft insulation pack it around the tank then take off the outer grill fil the void don't pack it tight then replace the grill. Make a polystyrene box to fit snug around the grill hold it in place with two kebab sticks poked through the polystyrene top through grill gaps to pierce the bottom layer of the box this should stay in place but for added measure duck tape strips. Can't be bothered, its ok, then hopefully next time you use it you don't have my trouble, I forgot it hadn't been drained and paid the consequences on first use the tank burst the tie bar that holds the tank to the housing broke because it was in frozen water/iced up during winter. this weakens the tie bar and it breaks.

bob, November 2015