Total Leakage Duct Pressurization Test

In the previous page on the basic duct leakage testing procedure we said that you pressurize the duct system and measure the airflow through the fan.

Total leakage duct pressurization test.

Disregards size of ductwork static pressure i e. Verification can take place via either a post construction test or a rough in test for the post construction test leakage measurement must be made across the entire system including the manufacturer s air handler enclosure with all register boots taped or sealed at a test pressure of 0 1 inches w g. If 1300 ft2 duct area 3 cfm leakage 100 ft2 300 ft2 duct area 13 cfm leakage 100 ft2 test pressure requirements problem. 25 pa across the system including manufacturer s air handler enclosure all registers taped or otherwise sealed post construction test.

The result of a total duct leakage test is a measurement of cfm25. However the blower for the test apparatus would have to produce 24 cfm at 10 to 12 static. Duct leakage measurements of flow requirements problem. Watch this 5 minute video for a quick look at how to use the tec duct blaster to conduct a total leakage duct pressurization test.

To find the total duct leakage that s basically all you do. The amount of air flow in cubic feet per minute required to pressurize the ducts to 25 pa of pressure. For our example with a seal class of c for the low pressure duc t the leakage would be about 2 cfm. Ducts shall be pressure tested to determine air leakage by either of the following.

The only other thing you need to make sure you do is keep the spaces where the ducts are at the same pressure as the outdoors as much as you can anyway. Test pressure higher than duct design. Smacna 2012 hvac leakage test manual shows the recommended leakage class. Total leakage measured with a pressure differential of 0 1 inch w g.

Leaky ducts will require a higher flow rate to achieve this pressure than tight ducts. The fan speed is increased to attain a pressure of 25 pa in the ducts. A duct leakage tester consists of a calibrated fan for measuring an air flow rate and a pressure sensing device to measure the pressure created by the fan flow. Total leakage measured with a pressure differential of 0 1 inch w g.

Thus it is not worth the cost of testing the low pressure duct for leakage. Both the 2009 and 2012 iecc require duct tightness to be verified.