The right type of compressor is also importent!
I have worked on reciprocating comp. which where on a two stage system with NH3. The compressors where not ment to run at low kapacity and when they did the discharge temp. was around 130-150°C. The result was poor oil return to the compressors because of a poor seporation. Way to much oil went to the system and made some problem there. Nothing could be done exept we change to a better oil which and got a little bit better oilreturn.
So pic the right compressor if you are running on low kapacity f.e. coldroom during the night and using NH3. Otherwise you will have problem with discharge temp.