Retrotec Commercial 441 and 451 DucTester - Manual (Page 29)

Page 29 of 56
©Retrotec Inc. 2015
6. Finding duct leaks
Locating leaks in the ducts can be a tricky process, and there are a number of methods that are used.
6.1 Using a smoke puffer
Smoke puffers work similarly to theatrical smoke for finding leaks, but on a much smaller scale. The
chemical smoke of Retrotec’s Air Current Tester is the same density as air, and therefore does not move
unless there is air movement. Puff out a small amount of smoke near suspected leaks, (for example,
near joints, or in front of registers), while the DucTester is connected to the ducts and running, and
notice the smoke either being blown away or being sucked in, depending on the direction of the test.
6.2 Using theatrical smoke
The use of theatrical smoke can be a very effective way to find leaks in a duct system. A theatrical
smoke machine is used to inject non-toxic chemical smoke through the DucTester fan, and into the duct
system. Walking around to check the duct systems will point out obvious leak locations where smoke
appears. This can help find hard-to-detect leaks in attics and crawlspaces. Using this type of detection is
called theatrical for a reason – it is quite a sight to see for homeowners and builders.
Caution: Make sure not to inject the smoke directly into the fan motor, but instead into the edge of the
fan housing. Also, make sure to clean any residue away from the flow sensors, motor and fan housing
when the show is over. The particles can block the sensors needed for measurements.
6.3 Using an infrared camera
An infrared camera can graphically display areas where cold air is infiltrating into a house or building, or
show from the outside, where hot air is exfiltrating. The camera can also show zones that are poorly
insulated, and would otherwise be invisible without opening up wall sections.
6.4 Using a wet hand
Sometimes, a damp hand is more than enough to feel the movement of air around a leak. Wet skin will
feel cool or cold in the path of moving air.