Scroll Compressors allergic to refrigerant liquid flood back - are they?

[Controlswiz]

Have come across frequent scroll compressor failures on Heat Pump Chillers. Are scroll compressors allergic to liquid flood back or is it something to do with the reverse valve surge while change over? Has someone experienced such a thing happening often?

[The Viking]

Generally scrolls are seen as more forgiving to liquid flood back than old fashioned rotarys.

However, why is there liquid flood back in the first place? It's not good for any compressor.

Also, surge when the reversing valve change over??? Surely the compressor is idle for this?

:cool:

[Jeremy Martin]

Don't know about chillers, but some split resi heat pumps don't kill the compressor for defrost. Suction pressure spikes briefly and the compressor sounds like it's taking liquid, makes me cringe every time. :rolleyes:

[tsangep]

Hi
Did you check for oil being washed out and compressor killed from lack of oil? Also scrolls hate operating in a vacuum and can lock up. Add more oil usually helps especially if the coil runs lower temps and gas velocity is low

[desA]

Cut the old compressor up & look at the level of carbon deposits. If excessive, then likely failure due to oil breakdown at excessively-high compressor exit temperatures.

This is a common occurrence for hot-water heat-pumps, for instance.

What fluid is the condenser dumping heat to?

[frank]

Installing a suction accumulator would protect the compressor from liquid floodback. Sort of a basic requirement on a reverse cycle heat pump.

[moideen]

Better to replace the accumulator, because accumulator oil return orifice and screen may be plugged with trash or may become plugged shortly after a compressor failure. This will result in starvation of oil to the replacement compressor and a second failure. Ensure the crank case heater is working at off cycle. After replacement the compressor, rest of the oil to be cleaned through suction and liquid line filters. Use a 100% alumina suction filter drier and remove it after 72 hour operation. During the next start up, record the sump temperature to observe the system flood back.