Water Tank - Boiler - Bypass System

I don't know how many times I have had to trace the plumbing to figure out the water circuit for the filling of the boiler and the bypass valve. The bypass valve when open will provide a piping system that allows the pumps (that are mounted to the engine that pump all the time when the steam engine is running) to "bypass" the filling of the water into the boiler. This is important because the boiler should not be filled to the very top ever. The boiler needs some head space for the steam to be generated and pressurized. This pressurized steam is what is sent to the engine to be expanded to drive the pistons up and down. Below is a hand drawing/sketch of the system with the bypass valve open.

I did not draw in the engine, but the engine drives the two pumps. The pumps will circulate water through the tanks in a loop. When the bypass valve is closed, then the water path changes as indicated in the next sketch.

With the bypass valve closed, the pumps will pump water into the boiler. The pumps are strong enough to lift the check valve ball and fill water into the boiler. You will notice that in the sketches there is a hand pump. This hand pump is used to fill or prime the boiler for the first time or whenever the boiler level is too low to fire up the boiler safely. To use the hand pump the bypass valve must be closed. If you don't close the bypass valve you will just be circulating most if not all of the water to the tank and not be filling the boiler.