Older condo leaked after servicing: drain insulation left open in trunking

The leak started after service, but the drain was not choked. In humid coastal condos, exposed cold drain sections can sweat inside trunking. Water near trunking often gets treated as a choke, even when the drain path is clear.

By Team Snowflake | Updated 28 Jul 2026

Case summary

Daikin Wall-mounted9 years oldCondoMarine Parade, Singapore

Concern: The owner thought the drain was blocked again because water appeared along the trunking.
Found: Drain insulation left open after service, causing condensation inside trunking
Key check: Checked whether water came from the drain tray or formed on the exposed insulated section
Result: The trunking stayed dry after the insulation was corrected and the unit ran normally. Removing the exposed cold surface stopped moisture from forming inside the trunking. The owner also had a clear explanation for why the leak began right after servicing and what to check if it ever returned.

What we were told

Water appeared along the bedroom trunking the day after servicing. The aircon still cooled and there was no water spilling from the front of the unit.

What we checked

We checked whether the indoor tray was overflowing. It was not. The water was forming inside the trunking near an exposed cold section. The timing after service told us to inspect disturbed insulation and covers. The coastal humidity made condensation more plausible because any exposed cold section inside trunking can sweat quickly. We left the unit running while the trunking was open, so we could see whether water came from the drain path or formed on the outside surface.

Drain tray flowed normally during a water test.
Trunking was wet around a section of exposed drain insulation.
The insulation wrap had been left open after servicing.
No pipe crack or drain choke was found.

What we found

A cold section of the drain route was exposed inside humid trunking. Moisture condensed on that exposed area and collected until it dripped out of the trunking. The open insulation created a cold spot inside an enclosed, humid space. Moisture in the trunking air condensed on that surface, then collected and dripped out as if the drain had overflowed. The water was real, but it was forming outside the drain path rather than leaking from inside it. That distinction mattered because the drain tray could pass water normally, so repeated flushing would not stop the sweating at the exposed cold section. Once the insulation gap was visible, the leak timing after service made sense.

What fixed it

We dried the trunking, rewrapped the exposed section, and confirmed the drain tray still flowed properly. No chemical wash or pipe replacement was needed. We corrected the insulation first, then ran the unit long enough to check both drainage and sweating. That separated the fix from a simple flush and avoided recommending chemical wash for a problem it would not solve. This was important because a drain flush can look successful while the cold exposed section continues to sweat after the technician leaves.

Outcome

The trunking stayed dry after the insulation was corrected and the unit ran normally. Removing the exposed cold surface stopped moisture from forming inside the trunking. The owner also had a clear explanation for why the leak began right after servicing and what to check if it ever returned.

What this case teaches us

Post-service faults need the reassembly checked

After servicing, check disturbed covers, hoses, insulation, and drain joints first. After servicing, disturbed insulation matters as much as disturbed drain hoses.
A trunking drip can be condensation on an exposed cold section, not always drain overflow. Water can form on the outside of a cold drain route even when the drain itself is clear.
The first wet point tells us whether to flush, reseat, or reinsulate. Tell us if the leak started after work was done. That changes the first checks and can keep the repair smaller.

Questions this case answers

Trunking is wet a day after servicing but the aircon is still cold. Why?

Water can form on the outside of a cold drain section rather than escape from inside it. In this coastal condo the drain tray flowed normally during a water test, yet the trunking was damp around a stretch of insulation left open. Humid air condensed on that cold spot and collected until it dripped.

Is a wet trunking always a blocked drain?

No, and treating every trunking drip as a choke wastes a visit. Flushing proves water can move; it does nothing about moisture forming on an exposed cold surface. Neither crack nor blockage turned up here. Rewrapping the bare section and drying the trunking ended it, with no pipe work and no chemical wash.

Should I mention that work was done just before the leak began?

Always. That single detail reorders the checks and usually keeps the repair smaller. Disturbed covers, hoses, insulation and drain joints move to the front of the queue. Here the timing pointed straight at insulation rather than the drain path, so nothing further down the run had to be dismantled.

Why would a flush look successful while the drip still returns?

Because the drain was never the source. A flush can pass cleanly while an exposed cold section keeps sweating after everyone leaves. Watching the trunking with the unit running separated the two: water was forming on an outside surface, not spilling from inside the pipe. Closing the insulation gap ended it.

Ready to get started?

Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.

WhatsApp us