Refrigerant lines for rooftop condensing units must penetrate the roof at some point. There are proper ways to create this penetration, and others are not-so-appropriate. A proper penetration sheds storm water, but also allows for removal and replacement of the line-set without disturbing the roof surface. A “goose-neck” opening, pictured here, accomplishes this purpose. A line-set penetration that relies on spray foam, or tar, or any other liquid-applied filler or waterproofing material will eventually leak causing damage to the building interior and to HVAC equipment.
Also, an HVAC service technician when faced with a line-set that is firmly set in liquid-applied sealant may not be equipped to adequately ‘re-seal’ the penetration after replacing the line-set; or he likely may be discouraged from replacing the line-set altogether as it can be difficult to remove an old refrigerant line after it has been cemented in place for years.