Sherman M, Walker I
Bibliographic info:
LBNL - USA, Home Energy, July/August 1998, pp 14-19, 1 fig, 1 tab.

Duct leakage has been identified as a major source of energy loss in residential buildings. Most duct leakage occurs at the connections to registers, plenums or branches in the duct system. At each of these connections a method of sealing the duct system is required. Typical sealing methods include tapes or mastics applied around the joints in the system. Field examinations of duct systems have typically shown that these seals tend to fail over extended periods of time. Three test methods were used to test the longevity of duct sealants: simple heating, cycling heat and pressure and cyclic aging. The most advanced method was the "aging" test, developed to evaluate the longevity of duct sealants by alternatively blowing hot (75°C, 170°F) and cold (-12°C, 10°F) air through test sections, with the apparatus cycling between hot and cold air quickly. The temperatures and cycle length were chosen to accelerate the aging process of the duct seals. The aging apparatus was able to test eight samples at a time, with the test samples constructed from standard duct fittings. The results of these tests were used to evaluate different sealants relative to each other, so that recommendations regarding duct sealants may be developed. Typical duct tape (i.e. fabric backed tapes with rubber adhesives) was found to fail more rapidly than other duct sealants.