Buying a new aircon? What to check before you install it

A new aircon is a long-term decision, and much of the regret comes from getting the basics wrong at the buying stage — the wrong size, too few indoor units, or a layout the flat can't support cleanly. A quick note on how we work: we install the unit you buy — we're an installation and servicing specialist, not a retailer — so you're free to shop the best deal. Once it's in, regular aircon servicing keeps it running cold for the full decade. Here's what to check first.

1. BTU — match the cooling to the room

BTU is the cooling capacity. Too small and it never gets cold while running flat-out; too big and it short-cycles and wastes power. As a rough starting point, match the room to the capacity below. Do not buy from this table alone: floor area, afternoon sun, glazing, ceiling height, occupancy and open-plan connections all affect the cooling load.

Ask the installer to show the room-by-room load assumption and the selected outdoor unit's capacity when several indoor units run at once. "System 3" describes the number of connected indoor units, not a guarantee that all three receive their headline capacity simultaneously.

2. System type — how many indoor units

"System 2/3/4" means one outdoor condenser serving 2, 3 or 4 indoor units. Undersize the condenser for the simultaneous load and you risk a unit that's never quite cold enough. Count the rooms you actually want cooled, how often they run together and pick to suit — and check your condenser ledge can take the size of unit a bigger system needs.

3. Pipe run and trunking

The copper distance between the indoor units and the condenser affects both cost and performance — longer runs need more copper, careful insulation and, beyond the manufacturer's pre-charge allowance, an additional measured refrigerant charge during commissioning. That is different from a later refrigerant top-up used to address low charge after a leak check. Think about where the trunking will run, too; a tidy install plans the casing route so it isn't an eyesore across your wall.

4. Ledge space and drainage

Check the condenser ledge actually fits the outdoor unit with airflow clearance, and that there's a proper condensate drainage path so the indoor units don't drip — a poorly planned path is a common cause of an aircon leaking water later on. Internal drainage with a pump is an option where gravity drainage isn't available.

5. Electrical supply

The selected system must match the circuit, isolator, breaker and available load at the DB box. On older flats with a full board, that can mean electrical work alongside the aircon install. An EMA Licensed Electrical Worker should assess and carry out any new or modified wiring; the aircon model or indoor-unit count is not enough to size it safely.

6. HDB installer and reporting requirements

HDB's air-conditioner installation guidelines vary with the flat's electrical provision and installation arrangement. Exterior units must be handled by a BCA-trained aircon installer, and owners may need a permit and/or the AC-02 completion report. Confirm the requirement for your block before work starts and keep the completed paperwork.

How install-only works

Once you've bought the unit, we dismantle the old system if any, mount the new indoor and outdoor units, run and insulate the copper, sort the drainage and wiring, vacuum and pressure-test, then test-run and check the cold output before handover. Installation starts from $350 for a System 1 with standard piping; bigger systems depend on the pipe runs and removal. See our aircon service for the full scope.

The takeaway

Get the BTU and system size right for your rooms, check the ledge, pipe run, HDB requirements and power before you buy. Use a BCA-trained installer for the aircon work and an EMA Licensed Electrical Worker where wiring changes are needed. Send us your floor plan or a few photos and we'll confirm what needs an on-site check before quoting.