I read some 9k -> 12k system upgrades.
Be careful of using a 12k FCU in a small MBR of new BTOs. It might be sized too big.
This causes higher RH % levels.
Not a local article, but it gets the idea across.
http://www.energyvanguard.com/blog-b...-Is-a-Bad-Idea
The converse is true. Undersizing an aircon causes low humidity but insufficient cooling.
You can try to use 2 x 9000 btu/hr aircon FCUs from 2 rooms. Third Bedroom you close the door. The 2 bedrooms with 9k FCU open the doors and use 2 fans to pump the air to the living room. Observe your thermo/hygrometer. Temperature would not drop a lot, but RH% would drop a lot.
This is because the coils are working 100% and very much maintained below the dew point temperature, but the cooling btu/hr is insufficient.