Retrotec Commercial 441 and 451 DucTester - Manual (Page 28)

Page 28 of 56
©Retrotec Inc. 2015
5.10 Cannot achieve test pressure
If the DucTester fan reaches 100% speed on the “Range 74” Range Ring before reaching the target
pressure, the fan is not providing enough air flow to reach the target pressure. Perform the following to
reach the target pressure:
1. Remove a Range Ring.
2. Change Range Configuration setting on the gauge to match the fan.
3. Re-adjust DucTester fan speed.
If there is no Range Ring installed (i.e., “Open” with no more Range Rings to remove), and the desired
test pressure cannot be reached at maximum speed:
4. If the duct pressure is close to the required test pressure (within 5 Pa), use the [@] key to extrapolate
to what the flow would be at the desired pressure.
5. Try the Duct Leakage to Outdoors test, which will neutralize duct leakage to the house.
6. Look for large disconnects in the duct system by pressurizing the house with the Blower Door and
putting smoke in front of the registers. Registers with high velocity smoke movement are a good
indication of a potential disconnect behind that register. Fixing the disconnect in the ducts may
reduce the leakage enough to continue testing the duct system.