Total Leakage Duct Pressurization Test

If 1300 ft2 duct area 3 cfm leakage 100 ft2 300 ft2 duct area 13 cfm leakage 100 ft2 test pressure requirements problem.

Total leakage duct pressurization test.

Disregards size of ductwork static pressure i e. Total leakage measured with a pressure differential of 0 1 inch w g. For our example with a seal class of c for the low pressure duc t the leakage would be about 2 cfm. Thus it is not worth the cost of testing the low pressure duct for leakage.

The amount of air flow in cubic feet per minute required to pressurize the ducts to 25 pa of pressure. 1 of flow on 3900 cfm system 39 cfm. Ducts shall be pressure tested to determine air leakage by either of the following. Duct leakage measurements of flow requirements problem.

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. Test pressure higher than duct design. The result of a total duct leakage test is a measurement of cfm25. 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.

To find the total duct leakage that s basically all you do. 25 pa across the system including manufacturer s air handler enclosure all registers taped or otherwise sealed post construction test. Smacna 2012 hvac leakage test manual shows the recommended leakage class. The fan speed is increased to attain a pressure of 25 pa in the ducts.

Both the 2009 and 2012 iecc require duct tightness to be verified. 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. If the test is at 6 static pressure for leakage class 3 compliance i e 9 6 cfm per 100 s f with 6 orifice differential and 6 duct test pressure the meter could only indicate 24 cfm. However the blower for the test apparatus would have to produce 24 cfm at 10 to 12 static.

Leaky ducts will require a higher flow rate to achieve this pressure than tight ducts. A duct leakage tester is a diagnostic tool designed to measure the airtightness of forced air heating ventilating and air conditioning hvac ductwork.