This has been going on for quite some time. Had one several years ago that needed to be swapped to facilitate piping, and I was told no by the factory. When I asked why, all I got was a blank stare (if you can get a blank stare over the phone). Never did get an answer. I told 'em that there was no possible way that it could make a difference, and that if we got the job, we would swap them and all would be ok. Unfortunately, we didn't get the job, so I can't say for sure............
On some Trane units endbells can't be switched because of our active oil return system. Oil will migrate towards the cooler temperature. The bolt patterns on the endbells are different so they can't be swapped. RTWD 134a Screw chiller.
There is no heat transfer reason that inhibits the exchange of the water boxes on the condenser, as long as you keep the condenser water inlet on the bottom and the outlet on top. The reason you can΄t do it physically, is that the tubes in the horizontal center of the closed water box side are not even with the tube sheet. The separation sheet welded inside between condenser water in and outlet would interfere with the condenser tube overlap.
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