Formation of water droplets on the surface of cold water pipes in air conditioning systems.

Article details

Formation of water droplets on the surface of cold water pipes in air conditioning systems. (Condensation on Chilled Water Pipes)
It is a common problem in air conditioning systems. Especially in areas where High relative humidity, such as Thailand

🔍 Causes of water droplets

The formation of water droplets is a result of condensation of water vapor in the air (Condensation) when the water vapor in the air comes into contact with the surface of the cold water pipe at a temperature lower than the dew point of the air in that area.
 • The cold water pipe has a low temperature (e.g. 7°C).
 • The air around the pipe has high humidity.
 • The dew point of air may be 15–20°C.
 • When the water vapor in the air comes in contact with the cooler surface of the pipe, It will condense into water droplets.

⚠️ Effects of water droplets
 • Water drips onto the floor, making the floor slippery. There was an accident.
 • Destroy ceilings, walls, or decorative materials.
 • Stimulates fungal growth.
 • Reduces the efficiency of the air conditioning system.

✅ How to fix and prevent

1. Insulate cold water pipes correctly.
 • Use closed cell insulation such as PE Foam or PU Foam.
 • Choose the appropriate thickness, such as:
 • If the water temperature is cold 6–8°C → use insulation thickness 19–25 mm.
 • The insulation must have no gaps and no steam leaks.

2. Seal the joints tightly.
 • Use insulating tape or specialized glue (Adhesive) to seal the joints.
 • Seal all leak points where steam can penetrate.

3. Install the vapor barrier (Vapor Barrier).
 • Used as a protective layer to prevent water vapor from penetrating the insulation.
 • Recommended use of aluminum foil. or specific moisture-proof materials

4. Improve ventilation.
 • Increase ventilation to reduce humidity in the area.
 • May install ventilation fans or humidity control systems. (Dehumidifier)

5. Check the humidity in the engine room or ceiling.
 • Control Relative Humidity not to exceed 60%.
 • Install temperature and humidity meters. to plan protection

📌 Summary

The formation of water droplets on the surface of cold water pipes is caused by moisture in the air coming into contact with the surface at a temperature lower than the dew point. The important solution is Choose the correct insulation Install firmly and prevent water vapor from penetrating. Including controlling humidity in the surrounding area