Everething Bell €

Although i have a degree in Mechanics, i am (was) specializing in Machine Tools. Never studied a thing about motors or compressors. All i know is from fixing my cars and negotiating with mechanics (diagnosing the cars for them so i can tell them exactly what's wrong and save money.)

So i never knew what a fridge compressor look like. Until today. But i don't want to talk about the compressor itself. In a way it's just a reversed engine. It's got a motor and a cylinder with a crankshaft and a piston or more.

What i want to talk about it's the encassing. It looks exactly like two bells put together. The lower bell covers a biger piece of metal with some sort of maze that is not vibrating and actually dampens the vibration of the compresor. But the upper bell, shorter, covers the noisy part.

Problem is the bells themselves are kinda thin and vibrate like ... bells! Alhough it covers most of the noise from the compressor, they vibrate in turn to their own resonance frequencies. So you have to dampen that as well.

The designer's solution is the evaporating pan in top of the upper bell. It is tightened to the bell with a bolt and nut and glued as well.

When i moved into the appartment, the evaporating pan was full of some stuff that i still don't know what was made of, probably mineral insulation from the attic or from under the bathroom that somehow made its way in the appartment and ended  in the water in the evaporating pan and in time got glued with the formaldehyde resin that was evaporating from the fiberboard floor and re-polymerized in there.

It was stinking really bad so i had to remove it using a screwdriver, it took me and my wife a couple of hours to do so.

I diverted the water from the freeze-thaw cycle in a one gallon water container that i had to empty monthly. I did that because it was collecting water from the air, acting like a dehumidifier. But the pan was leaking as well and i didn't know until recently, again. And i took it off and i saw it was glued to the upper bell. But the glue was probably very cheap stuff and the pan separated from the bell and the bell was vibrating producing ultrasound. But when i took it out, the level of ultrasound increased suddenly. And actually started to have back pain, hands pain, all kind of pains.

The lower bell was installed on four rubber mounts that shrank and allowed it to rattle at low frequencies.

These days i rebuilt the mounts, retighten the bushings, glued back the pan with sillikon seal, and fill the pan wiht gypsum.

I don't know if i cut all the vibrations, but it is definetelly a low quiter now. But my ears are still ringing. My wife can't hear a thing. Tomorrow i'm going to try to see if i can dampen the high frequencies a little bit more.

I even tried to wrap the bells in rags and it works pretty well but it heats up too much and had to remove them.