noisy electric boiler

electro

I have a 3-zone baseboard radiant system with a 10-year-old Electro-Boiler EB-MO-20 with outside reset. System pressure is about 15 lbs. In mild weather the system works fine, with no particular noise beyond ordinary expansion sounds. In very cold weather when water temperature is high and all four elements are on, there is considerable vibration from the boiler that is transmitted through the radiators. Very noisy, very annoying. When the boiler hits its 185 degree high limit and the elements shut off, the vibration ceases instantly even with continued heat call. The circulator is completely silent in any conditions. I have tried turning the panel temperature select screw down but the boiler still heats to the 185 limit (unless I turn it to about '3'--then the water temp goes too low to heat the house). Any suggestions?

Jamie Hall

Is this vibration a 60 hertz (power line frequency) hum type vibration? (might also be an octave higher -- 120 hertz). I would suspect that something holding (or near -- at full power they may have a considerable magnetic field) the heating elements is loose.

ratio

First guess would be a buzzing contactor on the last stage. You might be able to figure it out by probing the contactors with a piece of ½" PEX pipe if it isn't obvious which one it is. It could also be a magnetically induced vibration in the element or some of it's wiring, or a support like Jamie mentioned.

electro

Thank you, I will check that. The covers on the baseboards rattle like a train's going by, and we're not on the tracks!