Posted by Harold Kestenholz - Hydronic Network on October 26, 2001 at 09:54:18:
In Reply to: Slant/Fin Galaxy Start-up Hum posted by Tim D on October 26, 2001 at 08:53:22:
The Galaxy series is a very simple, dependable design with nothing in it to expect other than quiet heat. Two sources of noise are possible.
Incorrect low gas pressure can permit the gas to burn inside the strip burner(s) making a noticeable hum. If this is the source of noise, a trained gas combustion technician with the proper instruments is required.
A circulator can make humming throughout the system or near the boiler. The circulator can be checked by removing power, disconecting the circulator wire, reconnecting power, running the boiler for a few minutes before it reaches 200F. If the noise stopped, the circulator was making the noise. Replacing the circulator and putting the wires back properly could be a solution.
http://www.slantfin.com/boilerpdf/GG-10PL.pdf