If refrigerant piping surface temperatures drop below the dew point, what action is recommended?

• A. Insulation should be used
• B. Insulation is optional
• C. Insulation should be avoided
• D. Increase refrigerant charge

Answer: (A)

Condensation forms on a surface when that surface is cooled below the surrounding air’s dew point. Refrigerant piping can become extremely cold, so its surface often drops below the room’s dew point and moisture from the air condenses on or around the pipe. Insulating the piping slows heat transfer from the room to the pipe, helping keep the outer surface at or above the dew point and preventing moisture from forming. This not only stops sweating on the pipe but also improves energy efficiency by reducing heat gain to the cold line. (A vapor barrier is usually included with the insulation to prevent moisture from migrating into the insulation.)