I too use the BLOW OUT method winterizing my OFF-ROAD POPUP trailer.
When I drain my fresh water tank low drain point I open the cold and hot water faucets and also move the hot water heater spring loaded high pressure valve to open. This drains down my hot water heater to just below the bottom COLD WATER inlet.
There is still a small amount of water left in the bottom of the Hot water heater but given all of the open room inside the tank allows for expansion especially if I leave the top spring loaded high pressure valve open during the cold months.
After I have the fresh water tank drained then I connect my 12VDC tankless air compressor to the City Water Inlet using an adapter. This blows out all of the lines down the sink as well as the outside shower setup when those valves gets opened.. After all the lines are blowed out with air then I add a small amount pink stuff to the P-traps. Been doing this for the last four years or so and I am still on my one gallon bottle of pink stuff..
The beauty of using the blow out method for me is I can go back to using the water system again by just filling the fresh water tank. My blow out method only take under ten minutes to winterize the lines. The other beauty is I never fill my water lines with bad tasting pink stuff...
Granted where we live here in Northern Neck VA is not a real bad freezing winter experience but I do however like to winter camp up along the Blue Ridge and sometimes inside WVA where it does get pretty cold over night.
This works out great for my small footprint POPUP trailer.
Roy Ken
