QUOTE(cherroy @ Dec 28 2010, 09:36 PM)
I only know there is a standard rule of word (among the installer)
1 HP is for 12 x 12 feet room.
But actual fact is all about BTU of the air-cond as different brand of air-cond deliver different BTU despite all are rated at 1HP.
BTU required = 12 x 12 x (60~80) (factor which can be varied due to room condition, like insulation, people etc, poor insulation mean higher number, just a rough guess/estimate)
If we take 60.
Then the room require 12 x 12 x 60 = 8640 BTU.
Most 1 HP has no problem to have this BTU.
If you are iPhone user, you can download the York app that I find it useful to work out how much BTU cooling capacity needed for your room.
Just specify the dimensions of the room, how many glass windows that you have in your room, and how many people that will stay in that room.

It also takes the size of the window into consideration as well, and which way that the window is facing. If it face the sun while it rises or sets, that obviously will add more cooling capacity.

My room's BTU is 11291, so I have to settle for 1.5HP aircond.
This post has been edited by mohdimran: Dec 29 2010, 01:56 AM