Why does an inspector note refrigerant lines that pass through a wall without a sleeve or seal?

Where refrigerant lines pass through an exterior wall they create a penetration in the building envelope, and an unsealed one is an open path. Air moves through it in both directions, driven by wind and stack effect, carrying moisture that can condense within the wall cavity. Water runs in along the lines during driving rain, particularly where the penetration is not sloped or sleeved, and wets the sheathing and insulation behind the cladding. And the opening is a ready entry for insects and small rodents, which is one of the more common ways pests get into a wall. A sleeve with an appropriate sealant closes all three paths while still allowing the lines to move slightly with temperature. The inspector reports the unsealed penetration as a building envelope defect rather than a mechanical one.

An unsealed penetration is an open path through the envelope, admitting air and the moisture it carries, water running in along the lines during rain, and insects or rodents. A sleeve and sealant close all three.

Penetrations through the building envelope require sealing to control air and water movement and to exclude pests. Refrigerant line sets passing through exterior walls are sleeved and sealed while allowing for thermal movement.

Every Hole Is a Path — for air, for water and for anything with legs. Seal it or all three use it.

Check the line set insulation while you are there. Missing or ultraviolet-degraded insulation on the suction line is an efficiency and condensation finding that usually accompanies this.

• •Treating the penetration as a mechanical rather than an envelope finding
• •Overlooking degraded line set insulation at the same location
• •Missing other unsealed envelope penetrations nearby