When you start shopping for a new air-conditioner in Singapore, you’re immediately hit with a wave of confusing jargon. “System 2,” “System 3,” “System 4”… what does it all actually mean? It’s enough to make anyone’s head spin.
At Vedha, we believe in keeping things simple. So, let’s demystify this once and for all. Think of your aircon system like your home Wi-Fi. You have one central Wi-Fi router that sends a signal to multiple devices—your phone, your laptop, your smart TV. An aircon system works the same way.
This guide will walk you through the differences between System 2, 3, and 4, helping you choose the perfect, most cost-effective system for your HDB flat or condo.
“System 2, 3, 4? Simple Lah.” – What It Really Means
The concept is actually very straightforward. The “System” number simply refers to how many indoor units (the fancoils on your walls) are connected to a
single outdoor unit (the compressor on your AC ledge).
- System 2: 1 outdoor unit connects to 2 indoor units.
- System 3: 1 outdoor unit connects to 3 indoor units.
- System 4: 1 outdoor unit connects to 4 indoor units.
The most important thing to understand is that the outdoor unit is the “heart” of the entire system. It does all the heavy lifting of removing heat from your home. The power and capacity of this single outdoor unit determines how well all the indoor units will perform.
Which System for Your Home?
The right choice depends entirely on your home’s layout and your family’s cooling needs.
For the 3-Room HDB Flat (approx. 65 sqm) For most 3-room flats, a
System 2 is the most practical and cost-effective choice. A common setup is one unit for the master bedroom and one for the living room. This focuses your budget and cooling power on the areas you use most. Only upgrade to a System 3 if the second bedroom is used daily, for example as a home office or a child’s room.
For the 5-Room HDB Flat (approx. 110 sqm) A
System 4 seems like the default choice here to cover the three bedrooms and living room. But you must be aware of the
“Underpowered Condenser Trap.” Many homeowners choose four powerful indoor units, but the total cooling power (BTU) they demand exceeds the maximum capacity of the single outdoor unit. When all units are switched on, the system struggles, and every room feels weaker than expected.
- Technician’s Tip: For high-usage families in 5-room flats, consider two separate systems (like a System 3 for the bedrooms and a System 1 for the living room). This costs more upfront but guarantees powerful, dedicated cooling.
For the 2-Bedroom Condominium (approx. 70 sqm) With their compact layouts, a
System 2 is almost always the perfect fit for a 2-bed condo. It provides targeted cooling for the two bedrooms, uses less electricity, and fits perfectly on the limited space of a condo AC ledge.
Cost vs. Performance
- Upfront Cost: The price rises significantly with each additional indoor unit. A System 4 can cost more than double a System 2.
- Running Costs: With modern inverter technology, running just one indoor unit on a System 4 is not significantly more expensive than on a smaller system. The outdoor unit intelligently scales its power to match the demand. Your electricity bill is mainly determined by your usage habits—how many rooms you cool at once.
- The Biggest Risk (The Single Point of Failure): A multi-split system relies entirely on one outdoor unit. If that single compressor fails, your entire home will be without air-conditioning, a major inconvenience during a heatwave.
Final Checklist
- The Outdoor Unit is King: Always check the BTU cooling capacity of the outdoor unit. Ensure it is powerful enough to handle the number of indoor units you plan to run simultaneously.
- The 5-Tick Rule: As of 1 April 2025, all new multi-split systems sold in Singapore must be 5-tick rated. Choosing a 5-tick model now is a smart way to “future-proof” your investment and is the only way to use your S$400 Climate Vouchers.
- Don’t DIY the Decision: This is a complex calculation. Getting it wrong leads to years of inefficient cooling and high bills.
The Vedha Solution: The Perfect System, Guaranteed
Choosing the right aircon system is a complex balance of power, layout, and budget. It’s a decision you shouldn’t have to make alone.
At Vedha Construction, our expertise is your peace of mind. Our experienced technicians provide a free, no-obligation site survey to analyze your floor plan and understand your family’s unique needs. We’ll recommend a perfectly sized and balanced system—whether it’s a System 2, 3, or 4—that is both effective and fully compliant with all HDB and BCA regulations.
Stop guessing and get an expert recommendation. Call Vedha Construction at 96540044 today to schedule your free site survey!
We specialize in Aircon installation, repair, and service. We have all type & model of recon compressor, full set & fancoil. Our technicians are highly proficient in their respective field and repairs and fixes aircon of various brands.
