Acson good reliable, long lasting but compressor tends to become noisy after few yrs. FYI ACSON & YORK made under one roof same factory at OYL... So ACSON & YORK same... If for office use ok la since compressor far outside wont be so disturbing, if house better get Panasonic price almost same also. Mitsubishi better but bit expensive.

You don't need 3-phase even if u add another 1hp.
Normally 1hp ~ 4amps
1.5hp ~ 7amps

So your hse ((7amps x 2 = 14amps) + (4amps) )=28amps

Normally a house fuse (d big fuse beside TNB meter) is 32amps, but we can buy a 60-63amps at any electrical shop and change it ourselves, but make sure your cables are good quality ones. In my house i changed it to 63amps and using 2x2hp 1x1.5hp 1x1hp with a single phase... If ur total house amps exceeds 55amps then maybe you can tink of upgrading to 3-phase. To check ur total house current load u will need a clamp meter, and check it at the incoming of ur house near the TNB meter