How can I hide aircon trunking in an HDB flat?

How to hide aircon trunking in an HDB flat: the options

You have four practical ways to hide the pipes: leave standard trunking but paint it to match the wall, run it tight along the cornice and ceiling line, cover it with carpentry, or box it into a false ceiling. Which one suits you depends on where your fan coils sit compared with the condensing unit on the ledge. In a 4-room BTO, for example, the pipe run from the ledge to a far bedroom may cross the corridor ceiling, and that long stretch is usually the part owners want gone.

A neat route costs less effort to hide than a messy one, so the installer's choices matter as much as the cover. For the wider rules on ledges and installers, see our guide to HDB aircon installation rules.

What HDB requires of aircon piping

Whatever you use to hide the pipes has to sit on top of a route that meets HDB's rules. On its air-conditioner installation works page, HDB says all aircon piping must run internally, pipe joints must be insulated, and condensate must discharge into a floor trap in the flat. There is to be no hacking through reinforced concrete.

The same page says air-conditioners must be installed by a Building and Construction Authority (BCA) trained air-conditioning condensing unit installer, and the installation report goes to the HDB Branch within 14 days after installation. The aircon ledge is to be used strictly for the condensing unit only, so you cannot park the piping, a pump or storage there to free up space indoors.

In practice, this means the concealment question is really about the indoor part of the route. Bring these points up with the installer before the site visit ends, not after the pipes are fixed. Our aircon installation FAQ covers more of the questions owners raise at this stage.

Aircon piping in a false ceiling

A false ceiling box is the cleanest look, and it is the option most likely to cause trouble if it is built without thought. The usual aircon piping false ceiling setup is a narrow L-shaped box along a corridor or the edge of the living room, with the refrigerant pipes and the drain pipe running inside.

Three things deserve attention:

• Access panels. Ask for panels at bends, joints and the point where pipes enter each room. Without them, a technician may have to cut the board to reach a fault.
• Hidden leaks. A dripping joint or blocked drain above a ceiling can go unnoticed until a brown stain appears or the board sags.
• Condensate slope. The drain pipe needs a steady fall towards the floor trap. A box built too shallow can force the pipe flat, and water may sit in it.

If you already see damp patches, our page on aircon leaking water explains the common causes.

Planning before installation

The right time to hide pipes is before they go up. Once trunking is fixed, every change means removing and rerunning it. Sit down with your floor plan and decide three things first.

Start with the indoor unit positions. A fan coil placed on the wall nearest the ledge needs a much shorter run than one on the opposite side of the room. Next, agree the route itself: which walls, which ceiling line, and where it passes through to other rooms. Finally, mark where the power point and isolator for each unit will go, so the wiring and the pipe cover can be planned together rather than as two separate lines.

If your renovation contractor is building carpentry or a false ceiling, get them and the aircon installer talking early. Our aircon installation quote checklist lists what to confirm in each quote.

Existing trunking: tidy fixes

Already living with white trunking across the wall? You have a few low-disruption choices. Painting the cover to match the wall is the simplest, and many owners in older flats do it during a repaint. Ask the painter which paint suits the trunking material, and keep the clip-on lids free so they still open.

A cabinet or shelf can also screen a short vertical drop, as long as it does not press on the pipes.

For a bigger change, wait until you replace the units. A reinstall is the natural moment to ask the installer to re-route along a neater line. Quotes for this depend on the length of the new route and the work involved; our guide to aircon installation cost in HDB explains what goes into them.

Keeping access for servicing

A hidden route still has to be serviced. HDB's guide to maintaining air-conditioners says to have the condensing unit serviced regularly by a licensed service provider, to ask whether its brackets need replacing because of rust and corrosion, and to clean the air filters to keep airflow optimal.

None of that works if the fan coil is boxed in tightly or the access panel sits behind a fixed wardrobe. Leave clear space around each indoor unit, keep panels free of shelves and décor, and tell the technician where they are. When you book aircon servicing, mention the false ceiling so they come prepared.

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