Shophouse cassette leak traced to drain line sludge, not cracked pan
Aircon case in Chinatown, Singapore: water leakage traced to drain line blocked with thick biological sludge, causing condensate to back up and overflow the pan edges after targeted diagnosis checks.
Case details
What client reported
The unit has been dripping water onto the shop floor and merchandise for the past week. Another company inspected it and said the drain pan had cracked from age. They quoted for lowering it from the ceiling to replace the pan. The unit is about fifteen years old.
What we found
Before assuming the pan had cracked, we tested the drain line and checked whether the water was overflowing the pan or leaking through it.
- Drain line was completely blocked — thick sludge had accumulated inside and no water was flowing out
- Condensate was filling the pan and overflowing at the lowest corner, dripping down along the ceiling mount
- After flushing the drain line clear with pressurised water, drainage resumed and the overflow stopped immediately
- Pan surface was inspected after draining — no cracks, holes, or visible corrosion found on the pan body
Fifteen years of continuous operation had allowed biological sludge to build up inside the drain line until it was fully blocked. With no outlet, condensate accumulated in the pan and eventually overflowed at the lowest point. The pan itself was structurally intact — the water was going over the edge, not through the pan.
What we did
The drain line flush resolved the leak completely. No pan replacement or ceiling work was needed. The client was advised to include drain flushing in their regular servicing schedule to prevent future blockages in this older unit.
The dripping stopped immediately after the drain was flushed. The original pan and cassette unit remained in place. No ceiling access or dismounting was required.
Timeline
Day 1
Cassette dripping onto merchandise — told drain pan had cracked and needed ceiling work
Day 1
Flushed the drain line and confirmed water flow before inspecting the pan for cracks
Day 1
Drain line flushed clear, pan confirmed intact — dripping stopped immediately
What we learned
Cassette drips — blocked drain vs cracked pan in older units.
- A cracked pan allows water to seep through the pan body even when the drain line is flowing. A blocked drain forces water to overflow the pan edges. Both produce dripping, but the overflow pattern and drip location differ.
- In older commercial cassette units, biological sludge accumulates in the drain line over years of continuous operation. The warm, damp environment inside the drain is ideal for growth. Regular drain flushing prevents this.
- Before recommending a pan replacement that requires ceiling access and significant labour, the drain line should be flushed first. If the dripping stops and the pan surface shows no cracks, the pan was never the issue.
Best next step
If your unit is behaving similarly, start with the service path that fits this case before approving broader scope.
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