Duct-system leakage: how much is too much? Taking the guesswork out of fan-power contingency...

Air-distribution-system leakage generally is accepted because zero leakage, while ideal, is patently impractical. How much leakage is tolerable, however, remains the subject of debate and confusion. In the case of ductwork, consideration must be given to the tradeoff between the cost of sealing--and, perhaps, verification testing--and the energy savings that come with lower fan operating power.

Other than ductwork, potential locations of air leaks include connections to diffusers, registers, and terminal boxes; fire-damper connections; access doors; and system penetrati