When driving a Stanley to an event such as a car show it is always good practice to insure the boiler is plenty full of water.  If the car is to sit for several hours there will inevitably be steam which will leak from steam piping valve stems, through the throttle if it's not tight, and from similar sources.  The leaking steam effectively lowers the amount of water contained in the boiler over time.  Filling the boiler to a higher level than what the steam automatic calls for is one way to insure a low water condition does not occur.

One use of the water automatic hand bypass valve is to over fill the boiler prior to stopping the car for a lengthy period of time.  Several miles from stopping the water automatic hand bypass valve should be closed to allow all water delivered by the power water pumps to be directed into the boiler.  Closing the water automatic hand bypass valve closes off the return path to the water supply tank and forces all water from the power water pumps to flow into the boiler.  When using the valve it is very important to closely monitor the boiler water level indicator.  The boiler should not be filled more than two-thirds to three-quarters full as excess water in the boiler can be carried over into the steam supply, reach the engine, and cause severe damage.

Another use for the water automatic hand bypass valve is to insure the boiler siphons full of water after being blown down.  After driving a Stanley the boiler is "blown down".  This operation drains all the water out of the boiler (the pilot and burner are extinguished before a blow down is done) which includes any impurities contained in the water.  When the boiler cools and the steam inside the boiler condenses back to water a perfect vacuum is formed.  If the boiler is sealed tight and all valves and packing do not leak, the vacuum that is created inside the boiler will draw water through the power water pumps and into the boiler.  For this action to occur it is necessary to close the water automatic hand bypass valve to close off the discharge path back to the water tank as it would allow air to replace the vacuum and not water.  With the boiler full of water oxidation (rusting) of the inside surfaces of the boiler are greatly reduced thus prolonging the boiler's life.