Basically you get as much of the water out as possible and add antifreeze to the traps and low points. Getting water out involves pulling the cathode/drain on your hot water tank and changing around the bypass valves so you don't have to fill it with antifreeze. There should be low point drains on the trailer (mine has two) Use only the PINK antifreeze which is safe for potable systems. I would reccomend a search on youtube as there are several good videos. Also you may want to pay an RV dealer to do this and watch first time. Once you know what to do it is pretty simple.
Answers & Comments
Basically you get as much of the water out as possible and add antifreeze to the traps and low points. Getting water out involves pulling the cathode/drain on your hot water tank and changing around the bypass valves so you don't have to fill it with antifreeze. There should be low point drains on the trailer (mine has two) Use only the PINK antifreeze which is safe for potable systems. I would reccomend a search on youtube as there are several good videos. Also you may want to pay an RV dealer to do this and watch first time. Once you know what to do it is pretty simple.