Aircon Trunking vs Concealed Piping in a Reno (2026)

Every aircon system needs pipes: refrigerant lines, a drainage pipe and electrical cabling running from the outdoor condenser to each indoor fan coil unit. The question in a renovation is not whether those pipes exist, but whether you see them. Run them along the wall in white casing and you have trunking. Bury them inside a false ceiling or boxed-up wall and you have concealed piping. It sounds like a small cosmetic call, but it affects your budget, your reno sequence and how painful a future leak will be — so it is worth deciding properly.

What aircon trunking actually is

Trunking is the rectangular PVC casing you see running along walls and ceilings in many HDB flats. Inside it sit the insulated copper refrigerant pipes, the condensate drainage pipe and the wiring that connects each fan coil to the condenser. The casing protects the insulation, keeps everything tidy and can be painted over to blend into the wall.

Installers like trunking because it is quick, standard and serviceable. If insulation degrades or a joint leaks, the casing pops open, the fault is visible and the repair is contained. For most flats where the aircon is installed without a major renovation, exposed trunking is the default — and honestly, once painted to match the wall, most people stop noticing it.

What concealed piping involves

Concealed piping hides the same pipes inside the structure of your renovation: above a false ceiling, inside an L-box, or within a carpentry box-up running along the top of a wall. The fan coil unit appears to float on the wall with nothing leading to it, which is the clean, showroom look many homeowners want.

The catch is sequencing. The pipes must be laid before the ceiling boards close, which means your aircon installer has to coordinate with your interior designer or contractor early — typically right after hacking and masonry, alongside electrical wiring. If you confirm your aircon vendor late, you either delay the ceiling works or lose the option to conceal. If you are renovating an HDB flat, factor this into your HDB renovation timeline from week one.

Cost: what the difference really is

The piping itself costs roughly the same either way — you pay per metre of pipe run regardless of where it sits. The difference is everything around it. Concealment needs false ceilings or box-ups (charged per foot run of carpentry or plastering), access coordination, and sometimes longer pipe routes to keep runs hidden. As a very rough 2026 guide, expect concealment to add a few hundred dollars to over a thousand per fan coil unit depending on how much ceiling work is involved, on top of the aircon system price. Exposed trunking is usually included in a standard installation quote.

Because ceiling carpentry is often bundled into your overall reno quote, ask for it to be itemised. It is one of those line items that quietly inflates, and it helps to see it in context of your total renovation cost for your flat type.

The leak question: the real trade-off

Here is the part that matters more than looks. Aircon pipes fail in two common ways: the foam insulation around the refrigerant lines degrades and causes condensation, or the drainage pipe chokes and water backs up. With trunking, you see the drip, open the casing, and fix it in an afternoon.

With concealed piping, the first symptom is often a yellow-brown stain spreading across your false ceiling — sometimes weeks after the leak started. Fixing it can mean cutting open the plasterboard, repairing the pipe, then patching and repainting. That is not a reason to avoid concealment, but it is a reason to do it properly:

• Insist on good-grade insulation with sealed joints — thin or poorly taped insulation is the main cause of condensation stains.
• Ask for a gradient-checked drainage run so condensate flows out rather than pooling inside the ceiling.
• Request access panels near joints and the fan coil connections, so future servicing does not require demolition.
• Pressure-test before closing up. A reputable installer will test the refrigerant lines before the ceiling is boarded.

Aesthetics and resale considerations

Concealed piping wins on looks — there is no debating a clean ceiling line versus a painted casing. In condos with high ceilings or cove lighting, the pipes often hide inside ceiling features you were building anyway, so the marginal cost is small. In HDB flats with lower ceilings, a full false ceiling to hide pipes costs you both money and headroom; a slim L-box along one wall is the usual compromise.

For resale, buyers rarely reward concealed piping with a higher price, but visible, yellowed trunking snaking across a living room can date a flat. If you are renovating with resale in mind, tidy trunking painted to match the wall is perfectly acceptable; spend the concealment budget where buyers actually notice, like kitchens and bathrooms.

Which setup suits which renovation

Choose exposed trunking if: you are not doing a full renovation, you want the lowest cost and easiest maintenance, you are a landlord fitting out a rental unit, or your ceiling height is precious. It is also the sensible choice if you are replacing an old system in a lived-in home, since concealment would mean new carpentry and repainting.

Choose concealed piping if: you are doing a full reno with false ceilings or L-boxes anyway, you value the clean look, and you are willing to pay for quality materials and insist on inspection access. If you are buying a new system as part of the reno, our guide to choosing an aircon for an HDB flat covers sizing and system types.

A hybrid is common too: conceal the runs in the living and dining area where guests see them, and use trunking in bedrooms and service areas where nobody looks up.

Maintenance either way

Whichever route you pick, the pipes are only half the story — regular servicing keeps the drainage clear and catches insulation problems early, which matters doubly when the pipes are hidden. Budget for scheduled servicing (see our breakdown of aircon servicing costs in Singapore) and treat any musty smell, dripping or ceiling discolouration as a same-week problem, not a someday problem.

Keep your installer’s piping diagram or photos taken before the ceiling closed. Five years later, when a technician needs to trace a pipe run, those photos can save you from exploratory hacking.

The bottom line

Trunking is cheap, honest and easy to fix; concealed piping is beautiful but unforgiving of poor workmanship. If you conceal, pay for quality insulation, drainage gradient checks and access panels — and photograph everything before the ceiling closes. Decide early, because this choice locks into your reno sequence within the first couple of weeks. Planning a renovation and want quotes that itemise the aircon works properly? Tell us about your project below and get matched with a renovation contractor.