In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Boiler heat exchanger makes huumming / buzzing noise
it is a weil mclain He-5 ser 3 put in in the mid 1980s w/ grundfus UP26-96F pump(looks to be about same age).
It sounds most like an ele water heater that has some build up in it, but no poping noise like you would here in a gas heater with a lot of buildup. I have heard several boilers with condensation and it sounds different than that. Jim