Winterisation
Winterisation, winterization, winterising, draining down, laying up, winter prep, drain down for winter
Winterisation is draining the entire water system before frost so that freezing water cannot split tanks, the pump, the water heater or the pipework. It is mandatory for any vehicle left unheated over winter.
The sequence: empty the fresh and grey tanks, open every tap and drain valve, remove and dry the filter, dump the water heater through the Truma safety valve or calorifier drain, run the pump dry for a couple of seconds, empty and rinse the toilet cassette, and leave taps mid-position. The cassette can be filled with potable-system antifreeze — automotive antifreeze is toxic and must never enter a drinking-water circuit. Not the same as Truma Frost Control, which dumps the boiler automatically at +3 °C but leaves the rest of the system full.