Frequently Asked Questions - DucTesters | Retrotec

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My duct test using DW/143 is not compliant, what am I doing wrong?


FanTestic checks that you have held the ducts at the test pressure for at least 900 seconds. If you do not, the test will show as not compliant. If you did a manual test and are entering the information into FanTestic, be sure to enter the time over which the test pressure was held. If this is greater than 900 and your other test conditions are correct, the test will show compliant.

Compliance means the test conditions comply with the stated requirements for a test in DW/143. Pass or fail means that the measured results are within the required level.

Is using a positive duct test pressure advantageous?


The main disadvantage to positive duct test pressure is that it blows off register seals or makes them leak. An LBL study showed a wide dispersion of results when the same duct test was repeated many times. Depressurizing will allow the use of lower sticking masking materials that are less likely to pull off the paint. In some cases plastic food wrap will work.

The main advantage to positive duct test pressure is that the flex duct doesn't contract as much. In cases where the flex runs to the ceiling this contraction effect might cause problems.

Testing using...

I have pinholes in my Model 240 or 340 DucTester flex ducts.


​One question we get a lot is about leaking flex duct that connects the ducTester to the return. We have tested the most ripped up flex available in our warehouse; it had way bigger pinholes and it measured 0.68 CFM at 25 Pa. When you measure a typical leakage of 100 CFM at 25 Pa or more, this is not even 1%. So we believe it is not worth spending money on replacing.

How do I know how many fans I need for a Blower Door or Enclosure Integrity Test?


We have created two tools to help you ​figure out how many fans you will need for your test.

To access them, click on the link below:

Then, scoll down to the Tester Tools section and download either the Blower Door or Enclosure Integrity version of the Number of Fans Calculator .

Next, open the file in excel and "Enable Editing" when a security warning appears.

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