Posted by Harold Kestenholz - Hydronic Network on October 29, 2001 at 11:08:03:
In Reply to: Noisy Crane boiler for baseboard hot water heating sysemat posted by H devereux on October 29, 2001 at 06:36:16:
Boilers may hammer when the water flow through the boiler is reduced. Local boiling occurs and the water hammers when steam collapses as hits the cooler water inside the boiler. The boiler may need an open loop from supply to return, pumping water at a minimum rate through the boiler to prevent hammer.
If there is a reverse-acting (circulator control) on the boiler, the circulator may need to run as soon as there is a demand for heat rather than delaying until the water is warm.