Posted by Harold Kestenholz - Hydronic Network on December 24, 2000 at 14:37:21:
In Reply to: Weil-McClane Boiler Noise posted by Tom Fischer on December 24, 2000 at 10:04:56:
This is not a strange occurrence, but one that should be prevented. When only one zone is open there is not enough circulation to cool the boiler heat exchanger, so the water boils violently. You can prevent this by having two zones opened manually all the time to produce a minimum flow rate. You can also install a bypass tube with a balancing valve from the circulator to the other side of the boiler to insure a minimum flow through the boiler when only one zone is open.