Had a contractor replace stolen suction and liquid lines running from the condenser to the coil. Unfortunately, he did a hack job where the lines meet the furnace, it has been leaking condensation on the outside of the furnace do to improper insulation. I called him back, he came out and just added more foil tape and rubber insulation. I have since fixed the insulation problem, running it farther into the furnace and have cut new sheet metal to cover the opening. I am now left with a 1/4 gap (at most) around both lines after running new sheet metal. I am looking for recommendations on the best way to seal this gap. From all recollection, it seems like the duct seal (mastic) is used by most pros, where it is built up thick around the lines. But i am not sure if this is industry standard or just the jobs that I have seen. Anyone familiar with the proper way the seal this gap. Keep in mind this was an added a/c unit by a previous owner and it does/did not have the new suction line fittings like most newer ac/furnaces have.