Duct Testing
Why Is Duct Leakage Important?
Leaks in forced air duct systems are now recognized as a major
source of energy waste in both new and existing houses. Studies
indicate that duct leakage can account for as much as 25% of total
house energy loss, and in many cases has a greater impact on energy
use than air infiltration through the building shell. Just as
important, duct leakage can prevent heating and cooling systems from
doing their job properly, resulting in hot or cold rooms, and
humidity problems. Worse yet, duct leaks can create air quality
problems by pulling pollutants and irritants directly into the
house.
Here are just a few of the problems resulting from duct
leakage:

- Leaks in the supply ductwork cause expensive conditioned air
to be dumped into the attic, crawlspace or garage instead of
into the house.
- Return leaks pull outside air (hot in summer, cold in
winter) into the duct system reducing both efficiency and
capacity. In humid climates, moist air being drawn into return
leaks can overwhelm the dehumidification capacity of air
conditioning systems causing homes to feel clammy even when the
air conditioner is running.
- Heat pumps are particularly susceptible to comfort
complaints from duct leakage, especially during the heating
season. Duct leaks can cause the air coming from heat pumps to
feel luke-warm or even cold during the winter. In addition,
leaky ductwork has been found to greatly increase the use of
electric strip heaters in heat pumps during the heating season.
- Leaks in return ductwork draw air into the house from
crawlspaces, garages and attics bringing with it dust, mold
spores, insulation fibers and other contaminants.
- Household depressurization from duct leaks and imbalanced
duct systems can cause spillage of combustion products (from
furnaces, water heaters and fireplaces) into the house.
For More information Check out this Video
Duct Sealing for Comfort, Energy and Indoor Air Quality from
Energy Experts on
Vimeo.

Excellent booklet from PG&E in California covering duct testing is available as a
download.
Click on the logo to download.