Cassette aircon vs wall-mounted side by side
The HDB rules in the table come from its building works guidelines and air-conditioner installation guidelines. For other systems, see aircon types or compare a portable, window or split aircon.
| Point | Ceiling cassette | Wall-mounted |
|---|---|---|
| Where it sits | In a false ceiling | On a wall |
| Needs a false ceiling | Yes | No |
| HDB false ceiling rules apply | Yes: minimum 2.4 metres clearance, non-combustible materials, no gas pipe inside (HDB) | No |
| Piping and condensate | Piping runs internally, condensate to a floor trap in the flat (HDB) | Piping runs internally, condensate to a floor trap in the flat (HDB) |
| Servicing access | Through the ceiling panel | At the wall unit |
False ceiling requirements
HDB's renovation guidelines for building works set three conditions for false ceilings: a minimum clearance height of 2.4 metres from the finished floor, non-combustible materials only, and no gas pipe enclosed within the false ceiling. The clearance rule does not apply to toilets and bathrooms.
Ask your contractor whether your room height leaves 2.4 metres from the finished floor below the false ceiling. If your flat already has one, ask whether it meets these conditions and whether it can take a cassette.
Installation rules in HDB flats
Under HDB's air-conditioner installation guidelines, flat owners are responsible for the proper installation, safety and stability of their aircon. A Building and Construction Authority (BCA)-trained air-conditioning condensing unit installer must install it, and an installation report goes to the HDB Branch within 14 days. All aircon piping must run internally, pipe joints must be insulated, and condensate must discharge into a floor trap in the flat.
The same HDB guidelines say you and the installer must check that the total running current of the condensing units does not exceed the approved electrical rating. In flats with a 30 amp main switch, a new 15A power point or 20A isolator for the aircon needs an electrical permit. Flats with a 40 amp main switch, or upgraded under the Main Upgrading Programme (MUP) or Home Improvement Programme (HIP), need no permit.
HDB's electrical works guidelines do not allow wiring to be embedded in reinforced concrete slabs, beams, columns, walls, wall plaster or other finishes. New wiring runs in surface trunking, above a false ceiling or behind carpentry.
Installation prices depend on the job, so read aircon installation cost in HDB flats before you collect quotes.
Servicing access and cost
A ceiling cassette is serviced through its ceiling panel, and a wall-mounted unit at the wall. Ask each company whether it services cassettes and how it reaches the drain pan.
The HomezyPro directory has no cassette servicing prices yet: fewer than 3 companies in it publish one. Ask for a cassette quote and check what the visit covers. For published servicing lines, see aircon servicing prices.
The National Environment Agency (NEA) energy saving tips say to check the aircon filter once a month and clean or replace it when necessary, service units regularly and get them inspected annually. With a cassette, ask where the filter sits and how you can reach it safely.
Airflow, sizing and room layout
NEA's tips on buying energy-efficient appliances say to choose the right cooling capacity. Its rule of thumb: capacity in kW equals the total aircon floor area in square metres divided by 5. Multiply by 3,412 for British thermal units per hour (BTU/hr). A 15 square metre bedroom works out to 3 kW, or 10,236 BTU/hr. Try the aircon BTU calculator for your room.
NEA says a larger aircon may be needed for rooms with double ceiling height, a large window area such as full-height glass, windows facing the sun (east-west) or extra heat sources such as bar fridges. Oversized units cost more to run and may not dehumidify well, while undersized units do not cool or dehumidify adequately. See aircon BTU and room size for more.
For split and multi-split aircons, NEA's Energy Label is affixed to the outdoor unit. It rates efficiency from 1 to 5 ticks and shows annual energy consumption in kWh and full load cooling capacity in kW. Compare these on the models you are offered.
Then look at the room. Ask each installer where they would place each type, given your bed, sofa or desk, and where the air would go.
NEXT STEP
See aircon companies in the directory with their published prices, the areas they say they cover and their sources.
Compare aircon companiesWhich one should you choose?
Work through these questions:
- Is there, or will there be, a false ceiling that meets HDB's rules on clearance, materials and gas pipes?
- Does your room height leave at least 2.4 metres below that false ceiling?
- Where is your furniture, and where should the air go?
- Can the servicing company reach the unit, and does it service cassettes?
- What do installers quote for each type, including ceiling and electrical work?
If there is no false ceiling and you do not plan one, a wall-mounted unit needs no ceiling work. When you collect quotes for aircon installation, ask each company to price both types for the same room.
Questions
Can I install a cassette aircon in an HDB flat?
HDB's false ceiling and air-conditioner installation rules apply, so check with your HDB Branch first. Under HDB's building works guidelines, the false ceiling needs at least 2.4 metres clearance, non-combustible materials and no enclosed gas pipe. HDB's installation guidelines require a BCA-trained installer and a report to the HDB Branch within 14 days.
Do I need a false ceiling for a cassette aircon?
Yes. A ceiling cassette sits in a false ceiling, so you need one. In an HDB flat, HDB's building works guidelines say the false ceiling must leave at least 2.4 metres from the finished floor, use non-combustible materials and enclose no gas pipe. A wall-mounted unit needs no ceiling work.
Is a cassette aircon harder to service?
It is serviced differently. A technician works through the ceiling panel, while a wall-mounted unit is serviced at the wall. Ask each company whether it services cassettes and how it reaches the drain pan. Also ask where the filter sits, because NEA advises checking the aircon filter once a month.
How much does cassette aircon servicing cost?
Fewer than 3 companies in the directory publish a cassette servicing price, so there is no published range yet. The cost depends on the job. Ask several companies for a cassette servicing quote, check what each visit covers and compare quotes for the same number of units.
Which type is more energy efficient?
Compare the models you are offered rather than the types. NEA's Energy Label rates aircons in ticks and shows annual energy consumption in kWh. NEA's buying tips say appliances with more ticks are generally more energy efficient, and suggest looking at life cycle cost: purchase price plus annual energy cost multiplied by lifespan in years.
Can a cassette aircon be installed in a toilet or kitchen?
Check with your HDB Branch and installer first. HDB's 2.4 metre clearance rule for false ceilings does not apply to toilets and bathrooms, and HDB's electrical works guidelines say power points should not be installed within bathrooms or toilets. In any room, including a kitchen, HDB's building works guidelines do not allow a gas pipe to be enclosed within a false ceiling.
Practical guidance for planning a home job in Singapore. Company prices come from the HomezyPro directory, each linked to its source; rules and safety points link to the agency or manufacturer that sets them. This is not a site inspection, a quote or professional advice for your home.
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