In commercial applications R134a is the only drop in for R12 chillers. However as you said there are problems with the capacity reduction and also oil changeout problems.
The characteristics are also not identical so you may also get head problems with a surging centrifugal compressor.
Why do...
The 85F (29.4C) cooling water temperature happens to be the ARI rating condition for chiller packages. ARI also stipulates 3 gpm/ton (53L/s/MW) condenser flow for this rating condition. The purpose of the ARI standard (550/590-98) to to ensure that there is a benchmark by which chiller packages...
The benefit of VSD centrifugal chillers will largely depend on its utilization range. If your application does have varying loads and also low ambient temperatures, it will suit VSD chillers. Remember that VSD chillers are efficient at part load with low ambient temperatures (cool condenser...