plunger to fill the pipes between the second check valve and the hot
water check valve. If the gauge shows I00 pounds of steam, the hot
water check is held shut by I00 pounds pressure, and when the space
between the check valves is filled with water, the next stroke of the
plunger will force the water through the hot water check valve, which is
held shut by the I00 pounds steam pressure so that the pump must force
the water against this hot water check valve with a power greater than
I00 pounds pressure. If the pump is in good condition, the plunger does
its work and the water is forced through into the boiler.

A clear sharp click of the valves at each stroke of the plunger is
certain evidence that the pump is working well.

The small drain cock between the horizontal checks is placed there to
assist in starting the pump, to tell when the pump is working and to
drain the water off to prevent freezing. When the pump is started to
work and this drain cock is opened, and the hot water in the pipes
drained off, the globe valve is then opened, and after a few strokes of
the plunger, the water will begin to flow out through the drain cock,
which is then closed, and you may be reasonably certain that the pump is
working all right. If at any time you are in doubt as to whether the
pump is forcing the water through the pipes, you can easily ascertain by
opening this drain cock. It will always discharge cold water when the
pump is working. Another way to tell if the pump is working, is by
placing your hand on the first two check valves. If they are cold, the
pump is working all right, but if they are warm, the cold water is not
being forced through them.


A stop cock should be used next to boiler, as you ascertain whether it