When I open up the box (approx 5x5) there are some wires, and what looks like a small electric motor.attached to the motor is what looks like a tiny metal square that is vibrating to make the noise.It is pretty loud.There is no labeling, writing, or marking to tell me what this part of the boiler is.Any ideas?
Buy a new one. More efficient and better for the environment. Safer too
this will be a 24 volt relay. The contacts are pitted on it and the coil is getting weak. Time to replace it.
What you describe sounds like a contactor. This is what is used to switch on and off the power to your boiler. Contactors are nothing more than high voltage switches controled by low voltage conductors. Contactors are used to reduce arcing when equipment is switched on and off. When the low voltage conductors that are being fed by the thermostat have voltage applied to them they create an electromagnet around the square piece(coil) you described. Somewhere on this square coil should be a set of contacts that are pulled closed by magnetic force when the low voltage control wires are energized. The use of electromagnets causes the contacts to engage and disengage much faster than a human finger can flip a switch, thus reducing arcing as the contacts are pulled together and separated. Now, to fix your problem.(hopefully) This is what I think you should try. Turn off the power to this contactor (high and low voltage). Once power is off, take some emery cloth or very fine sand paper and gently buff the contact points until all burn residue is removed. The buzzing you hear is most likely caused by insufficient contact caused by this residue. Put it all back together and turn back on. If the problem persist, then you will need to replace the contactor. Good luck.
