I quite rarely get involved with the installation of ceiling cassettes as I'm a service engineer, and deal with quite a bit of refrigeration as well as air conditioning. The thing that I always seem to take quite a while with is hanging ceiling cassettes. Usually I remove the tiles etc, put the threaded rods in and make a frame from channel before hanging another four rods to hold the cassette, but I'm sure there must be better ways than this as I seem to take quite a while to get the cassette centred. I know this probably sounds a bit trivial but any better ideas would be gratefully received.