I just picked up some new old stock Lieberts (1984 and 1990). Back then Liebert used 3-PH Hermatic Compressors on their 30k-70k BTU size units.
On the newer units I have, they use Scroll compressors.
I'm curious as to why?
I know scroll is supposed to be more efficient, but isn't hermatic more reliable long-term. If the hermatic style lasts longer, but is less efficient then scroll, how much less efficient.
I can easily swap out these NoS hermatic compressors with brand new copeland scroll units, but I'm not sure if its worth it.
On a side note, I have a unit with a Copeland 5-ton scroll (3-PH 460V) that has developed a significant vibration. Charge is good, sight glass is clear, lube is good, just has a bad vibration you can really feel on the floor up to 5-10 ft away. The comp is on rubber insulators, and if you push it in a certain direction it goes away a little, but not much. My technician told me not to worry or advance replace it, just let it run, if it breaks down will fix it then. I am concerned about performance loss, and the vibrations are annoying as hell.
-John