Why may water hammering occur in the economizer after starting of the Boiler Circulating pump prior to departure?
Looks like water from the economizer gets drained back into the boiler during the port stay. This results in water hammering when air pockets escape from the economizer coil after the circulating pumps startup.
During the port stay, after the circulating pump stopped, try to keep the Auxiliary Boiler water outlet valve ( the first valve on the circulating pump suction) in the closed position. The mentioned valve is a check valve, it should prevent a backflow of the boiler water from economizer back into the boiler. However it hasn’t been overhauled for a long time, it may start leaking, allowing backflow of water from economizer into the boiler.
