Why does the suction line need to be insulated?

expert EXPERT April 26, 2007

The large-diameter line (suction line or gas line) should be insulated along its entire length. The insulation performs two functions. 1. It prevents the suction line from sweating and dripping water inside the house. 2. The insulation also prevents the suction line attracting heat from the outdoors on its way to the condenser coil. We are trying to take heat out of the house and dump it outside. We don't want to gather outside heat and dump it into the suction line before it goes into the compressor.

Insulation may be missing because -

• it was never put on in the first place
• animals have chewed it
• service people or home inspectors have pulled it away to inspect or repair areas
• the insulation may have worn away

System performance will be adversely affected if the outdoor insulation is missing. If the indoor insulation is missing, water damage to the home may result.

Look for the insulation to be intact along its entire length. Pay particular attention to the outdoor section of the suction line.