Retrotec DucTester 341 - Manual (Page 53)

Page 53 of 83
©Retrotec Inc. 2014
11. Find air leaks in the ducts
Locating leaks in the ducts can be a tricky process, and there are a number of methods that are used.
11.1 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.
11.2 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.
11.3 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.
11.4 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.
11.5 Using a Pressure Pan
If a Blower Door system is available, checking all the registers with a Pressure Pan, prior to doing a duct
leakage test, can be useful for finding the leakiest part of the system, and for determining the most
conservative location for the DucTester system pressure pickup. A pressure pan test can also locate
large disconnects in the duct system, which may prevent the acquisition of a useful result in a full duct
leakage test. Set the Building Pressure to 25 Pa, and cover the register with the Pressure Pan connected
to the blue port of the DM-2; readings over 1 Pa indicate some leakage, readings over 5 Pa is severe
leakage at that register and 25 Pa indicates a complete disconnect.
Figure 39: Pressure Pans, large and small shown