Hi all I want to replace my current air conditional with new. I do have System 3 now and I plan to install aircon to my living room to avoid the haze situation (hopefully that it wont happen yearly). There is some option that I have here: Option 1: - System 4 to include all 3 rooms and living room. - Question will be what BTU is needed for living room (standard 5I HDB flat) Option 2: - System 3 for 3 bedrooms - single unit for living hall Any input is good and if you have any prefer contractor do recommend me. I'm looking in quality of work and cost. Thanks for viewing and thanks for input in advance.