Retrotec DucTester 341 - Manual (Page 10)

Page 10 of 83
©Retrotec Inc. 2014
1. Why measure Duct Leakage?
1.1 Energy loss
Leaky ducts pose health, safety and comfort problems and account for about 25% of the total energy
lost in a typical house. Because it’s “by far the most cost effective way to save energy” (EPA quote),
building codes now demand higher performance. Although visual duct inspections may be allowed in
some states, duct testing provides an easier, faster, verifiable pass /fail test result. In many instances, it
has a greater impact on energy use than air leaks anywhere else in the house or building enclosure. The
single largest cause of performance problems in small commercial buildings is often duct leakage.
The Duct Leakage Test Report software (in Excel) available from Retrotec can be used to estimate the
energy loss from duct leakage, as described in section 10.8.
1.2 Duct sealing saves money
A study completed in Florida examined 46 homes. They found that sealing the duct leakage reduced air
conditioner use by an average of 17%. This lead to savings of $110 per year, and the repairs were a
onetime cost of $200. Repeatedly, studies show that sealing leaky duct systems is one of the most cost-
effective measures that a home owner can take. Heating or cooling, the same holds true in all climates.
Another study in Arkansas noticed an average savings of 22% on heating bills when duct leakage sealing
was performed.
1.3 Problems from duct leakage:

Leaky return ducts pull unconditioned air into the duct system, and reduce the efficiency and
capacity of the HVAC system.

Conditioned (and expensive) air is lost directly to the outside, a crawlspace, or an attic.

If moist air is pulled into return leaks, the dehumidification system is overwhelmed and the
building will be uncomfortable.

An inefficient duct system will result in people seeking alternative sources of heating or cooling,
including increased use of electric heaters and fans.

Dangerous gases, mold spores, insulations fibers, dust, and other contaminants can be drawn
into the duct system and are blown into conditioned spaces.