Everybody says how great Kaeser compressors are, so I bought an SX5 rotary screw. Kaeser inspected my usage demands,inspected my exhaust ducting for proper design, and I have them do the service every year.
It is 3.5 years old with 3500 hours on it and it has already had a bad solenoid valve (warranty), a bad vent valve (warranty), the entire motor was replaced (warranty), and now the air end is shot, of course it's out of warranty and it's going to cost $5600 to fix a $7500 compressor. I think I have enough evidence to definitively call this thing a giant piece of shit.
The theory is that the compressor is not being utilized enough to cook water out of the oil. I don't know how much air we are using, but my old IR 18cfm piston compressor puts out very close to the rated 18cfm (tested by me, and yes I know the volume of compressed air is larger than the physical tank size), and that thing runs damn near all day long to keep up. So I'm not sure how we are under utilizing a 25cfm compressor bad enough to roast an air end in 3 years.
The Kaeser salesman even admits that this should not have happened, but so far Kaeser doesn't seem to want to give me any concessions toward either a replacement compressor or the repair bill to get this thing fixed. I'm told we should have a final answer to what Kaeser is willing to do 'before the holidays'. That would be nearly 2 months since I first brought up the problem. For a company that claims to be the king of reliability and service, this is piss poor performance.
So! What brands should I be looking at to quote my next rotary screw?
We ran for a while on a 15HP Kaiser screw and it never shut off under normal use. It would open the relief valve and draw enough amps for about 7.5 hp but really did not help our electric bill. Added another 500 gallons of air tank and it helped with the cycling but it would still run for 30 minutes and shutdown for 20 or so. Ended up switching back to a 10hp recip and the electric bill dropped by about $400 a month. I learned that you really need to size a screw compressor correctly and shut it down at night so leaks do not make it cycle even when you are gone. As for your system, you might look at increasing the size of your tanks so it does not cycle as often.