For homeowners, the big question often comes down to this: Should you choose a System 2, System 3, or System 4 aircon? Each option has its pros and cons, and selecting the right system depends on the size of your home, the number of rooms you want to cool, and your budget. This guide breaks it down clearly so you can make the best decision for your household.
What Do System 2, System 3, and System 4 Mean?
In Singapore, aircon “systems” refer to the number of indoor units connected to a single outdoor condenser unit.
System 2 Aircon: 1 outdoor unit + 2 indoor units
System 3 Aircon: 1 outdoor unit + 3 indoor units
System 4 Aircon: 1 outdoor unit + 4 indoor units
👉 For example, in a 4-room HDB, a System 3 setup is common: one unit in the living room and two units in the bedrooms. If you want all rooms cooled at once, you might need System 4.
Related guide: System 3 Aircon Meaning
Key Factors to Consider Before Deciding
1. Number of Rooms to Cool
System 2: Ideal for smaller house or households where only two rooms (e.g. bedrooms) need cooling.
System 3: The most popular choice for HDBs and condos, as it comfortably covers living room + 2 bedrooms.
System 4: Recommended for larger families or those who want aircon in every bedroom and the living room.
2. Room Size and BTU Requirements
Each room size requires a certain BTU (British Thermal Unit) for effective cooling. A master bedroom or living room generally needs higher BTU compared to a small bedroom.
👉 Use this as a quick guide:
Small bedroom: ~9,000 BTU
Medium bedroom: ~12,000 BTU
Living room: ~18,000 BTU
Read more: Aircon BTU Singapore Guide
3. Installation Space
HDB and condo owners often have limited space on the aircon ledge.
The outdoor condenser unit must fit properly, so make sure your ledge can support the weight and size of a System 3 or 4 unit.
Extra tip: Learn about BTO Aircon Ledges.
4. Energy Efficiency
Larger systems (System 3 or 4) don’t always mean higher electricity bills.
If you install an inverter system, it adjusts the compressor speed based on cooling needs, saving energy over time.
Related read: Inverter vs Non-Inverter Aircon
Common Mistakes Homeowners Make
Oversizing or undersizing the system – leads to wasted energy or poor cooling.
Not planning for future needs – young couples in a 4-room HDB may later want System 3 instead of System 2.
Choosing based only on price – cheaper doesn’t always mean better in the long run.
Expert Recommendations
3-Room HDB or smaller condo: System 2 is usually enough.
4-Room HDB or mid-sized condo: System 3 offers the best balance.
Larger HDB, condo, or landed property: System 4 ensures the entire home is covered.
👉 Always request a site survey before installation. Professionals can calculate the exact BTU needed per room and advise on the most efficient system.
Conclusion
The decision between System 2, System 3, or System 4 aircon in Singapore comes down to your home size, number of rooms, and budget. By understanding your cooling needs, you can save money, improve comfort, and avoid costly mistakes.
If you’re still unsure, contact Usin Aircon for a professional consultation. We’ll assess your home and recommend the best system tailored to your needs.
