On the topic of winterizing, here is my basic procedure for winterizing my D13.
I do not use any RV antifreeze on the fresh water system. The Truma Combi owners manual specifically advises not to use RV antifreeze unless a "bypass kit" is installed which keeps the antifreeze out of the hot water tank. My D13 does not have a bypass kit. The draining procedure above takes less than 30 minutes once you have done it a time or two. It has not let me down yet.
- Drain both fresh water tanks. I pull the main drain plugs on each tank with a 41mm 6-point socket.
- Briefly run the pump, with a faucet cracked open, and alternate the supply valve to ensure the supply lines from both tanks are empty.
- Empty water out of the small suction strainer that is located between the tank-select valve and the pump.
- Repeat previous 2 steps until no water is pulled into the suction strainer.
- Hook an air flush adapter to the city water fitting.
- Attach a regulated air supply. 30 psi may be safe, but 20 psi is more than adequate. You can even use a bicycle pump.
- Blow out all of the hot and cold lines by opening the faucets. Start at the highest fixture and work your way down:
- Ensuite Shower
- Ensuite Sink
- Outdoor Shower
- Galley Sink
- Draw-bar Spigot - Open the pressure-relief/drain-valve on the Truma Combi under the bed to drain any remaining water in the hot water tank. See Truma instructions for location.
- Repeat previous 2 steps until you are confident all water is out of the fresh water lines.
- Drain the supply tank for the Thetford cassette toilet.
- Run the flush pump to clear any water remaining water from the toilet flush water system.
- Add RV antifreeze to the toilet water supply until it is visible on the sight glass. Run the flush pump until the colored RV antifreeze runs in the bowl.
- Ensure the gray water tank and toilet cassette are empty.
I do not use any RV antifreeze on the fresh water system. The Truma Combi owners manual specifically advises not to use RV antifreeze unless a "bypass kit" is installed which keeps the antifreeze out of the hot water tank. My D13 does not have a bypass kit. The draining procedure above takes less than 30 minutes once you have done it a time or two. It has not let me down yet.
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