As mentioned, if your trailer is winterized, the HW tank should be empty. The bypass valves should be set to pass water directly from the cold water “supply” side of the water heater to the hot water lines that distribute hot water throughout the trailer. If no hot water is required, one could leave the valves in this configuration and simply have cold water out of the faucets, supplied by the pump or city connection.
If one prefers hot water, set the valves to allow water to flow through the water heater, as in normal use. Open a hot water faucet. Power the pump or connect city water. When water runs steady and has no air pockets, the water heater tank is full.
In the case of using the fresh water tank and pump, once the water heater is full it will remain full. If one consumes all fresh water, there would be no cold water for the pump to send to push the hot water out.
Jeff & Cindy
'09 27FB Flying Cloud
'91 350 LE MH