It is important to start off with a clean air duct system before applying the Aeroseal product. Air duct cleaning companies then can assure the customer of the very best product going forward. In addition, if the duct is not cleaned air duct cleaners will be introducing more velocity in the air stream because it has been sealed. Therefore, any dust or debris in the duct system prior to sealing may be blown into the conditioned space.
Yes, duct work in a slab is difficult to seal with great results, in order for duct work in a slab to be effective the duct work has to be laid in a porous material like pea stone. Or there has to be other duct work in the home that can benefit from the process. Aeroseal is not designed to keep water out of the duct work, and in many slab duct work situations that seems to be the problem. Aeroseal should not be applied to duct work that is too restrictive on the cold air return side of the duct system. Largely because the furnace is getting the air it needs from the leakage. If the return side is designed improperly and the duct work is sealed, the furnace is starved for air, making it run harder and in efficient, this could also cause the AC coil to freeze up, perhaps back draft or even more likely to cause uneven pressures in the home.
To Schedule an Aeroseal, Call 1-800-AIR-DUCT!