Most Alpenlites had 2 screw caps under the side near the steps. Take those caps off and open all faucets. If it has external shower open that valve also. I loosen the fitting at the inlet to the water pump and run the pump for a short time to draw in air to the pump . I leave the water tank full for emergency water in case of an earthquake. Drain the hot water tank. This works for me where it occasionally gets down to -5 degree F
2001 dodge 2500 auto, with billet Mojave Green torque converter with 2nd gear lockup mod, raptor 100 fuel transfer pump and gauges. RV75 injectors
94 Alpenlite 27sl with many mods.