Carrier 30RB compressor failures
We may be seeing an unusual number of compressor failure on our air-cooled, 30RB chillers.
It is concerning because the warrenty is or almost is up.
Many compressors have been replaced. Any thoughts at all?
Well how old is it and what is the model and serial numbers? Who replaced the compressors?
It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.
Take a look at the superheat set point in your configuration. I believe it is under option 1. If it is set at 7 degrees, raise it to 9 degrees.
Superheat, age, and serial numbers
Carrier, or one of their contractors, has been doing the compressor replacements.
One would think they would be looking at things like superheat.
I do not have serial numbers, and my understanding we are getting up toward 5 years of age.
I have not sure whether they are failing electrically, as in power problems, or mechanically, as in oil starvation or refrigerant slugging/carryover - and that makes a big difference.
I threw the post up just to see what sort of feedback came back.
Another little informational tidbit: This place uses 100% outdoor supply air - and that could make a difference, but maybe not. It a laboratory.
A low superheat setting on the early RB's was the cause of some compressor failures. Raising the setting from 7 degrees 9 might help you out, and is a very simple thing to do. It is also recommended by Carrier. I work on a lot of RB's, and have not had a problem with compressor failures. But then again I make sure the superheat is set at 9.
"Carrier, or one of their contractors, has been doing the compressor replacements."
This has been an issue for a while. In my area "Carrier" does the warranty now. There are a few machines around the Carrier distributor quality assurance group portrade it to be cheaper to let their buddy contractor that installed it do the repairs and the machines will never be right again. The engineer or installing contractor may have made a mistake. If their smart enough to figure out what they did wrong, then their not going to admit it. It's easier to blame the machine. Now that you've had repairs done on it, it's a gamble that you may have machine issues as well. A good technician is hard to find and every company has good and bad technicians. You may want to request a Carrier warranty representative to discuss your issues.
I would look at all the compressor starts verses hours and see if they are about equal or do the compressors have more starts on them from cycling? Nobody wants to sell a machine to small. They're usually oversized. Do you have 4-6 gallons of liquid volume per ton. Adding a storage tank could smooth it out. Do you have enough water flow ( 2.4 GPM per ton ). Some of these engineers think they can save on the pumps with 2.0 gpm per ton and after it's all piped in realworld your at 1.4 gpm per ton. The chart in the book is just a chart. Just because your numbers got you on the chart doesn't mean it's good.
Ditto on the superheat setpoint. Carrier has always said 10 degrees for years. This new style compressor claimed we could run lower. They thought 7', now they say 9'. I wonder about the concept with multiple compressors. One compressor running with a lower superheat pooling all that liquid up in the compressors next to it for the next compressor to slug when it starts. I've been bumping up the setpoint a degree for each extra compressor. I know of one unit that kept losing compressors or would go off on high motor temp and that all stopped after I bumped it up.