Residential field testing of an aerosol-based technology for sealing ductwork.

Research over the past five years has indicated that a significant majority of the cost of residential retrofit duct sealing is in the labor required to find and seal those leaks. This paper describes the results of a field investigation of the performance and practicality of sealing residential duct leaks from the inside by means of a technique based upon injecting a fine aerosol spray into the duct system. The field results presented are from 4 7 houses located in Florida. The field measurements included estimates of the labor and costs associated with conventional sealing, minute-by-minute tracking of the aerosol sealing process, and a breakdown of the time required for the various aspects of the aerosol sealing procedure, including: 1) setup, 2) aerosol injection, 3) supplementary conventional sealing, and 4) clean-up. These field tests indicated that this aerosol apparatus and injection protocol seals 60-90 cm2 of duct leakage per hour of injection time in the first half hour of injection, depending on the type of duct system. This sealing rate decreases to 20-40 cm2/h in the second ba1f hour as the ducts became tighter, the pressures increased, and the duct velocities decreased. Overall, the technology was found to be capable of sealing approximately 80% of the leakage it encountered, assuming that catastrophic leaks such as disconnected ducts had been repaired. The entire sealing protocol, including supplementary conventional sealing, took an average of 5.5 person-hours for the entire sample. The injection process itself represented approximately 20% of this time, and thus the overall time required was found to decrease significantly as the set-up and clean-up procedures were improved.