The circulator pump is making noise (buzzing or rattling). Is this normal? What can be done about this?

A: Air in the system leads to noise. The entire system must be inspected and bled.

B: The pumps may be oversized for the system in question. To fix this, throttle the pressure-side valves until the noises are eliminated.

C: The water in the system is boiling because the pump is undersized. This can be remedied by installing a larger pump.

D Excessive wear of bearings (rattling). The pump needs to be replaced.

S: A system that has already been entered into operation has become clogged. The system needs to be cleaned.