Step-by-Step Procedure
Complete Total Duct Leakage Test First
- Seal all registers and pressurize ducts to +25 Pa using the DucTester as usual.
Set Up House Pressurization
Ensure the blower door (or similar) is set to pressurize the house to +25 Pa relative to outdoor pressure.
Tube the house reference (typically the blue/Channel A port) so it reads building pressure.
Enable Target Pressures
- On the gauge: use
Set Pressure 25 Pafor both the duct (DucTester) and house (blower door) fans—ensuring both systems reach +25 Pa simultaneously.
([turn0search4], [turn0search3])
Neutralize House-Duct Pressure Difference
With both systems at +25 Pa, the gauge sees no pressure difference between house and duct—this isolates leakage to outdoors only.
Record Leakage Flow
Read the CFM displayed on Channel B; this directly represents duct leakage to the outdoors.
Why This Method is “Hard”
Manual balancing required: You must adjust both fan speeds precisely and maintain +25 Pa on each—with no automated control.
No @Pressure use: Extrapolation must be turned off, since it would otherwise try to guess “zero difference” and return invalid results.
([turn0search4])
Pro-Tips for Accuracy
Watch for fluctuations: If reading varies more than ±2 Pa, increase time averaging and allow time to stabilize.
([turn0search3])Ensure all registers remain sealed to avoid false readings from bypass leakage.
Make sure the gauge’s device and range settings match the DucTester’s installed plate.
(Standard gauge setup procedures)
