Retrotec DucTester 200 Series Residential Applications - Manual (Page 64)

Page 64 of 91
©Retrotec Inc. 2015
blocked with a drop of water which still allows the gauge to work but the readings are only a fraction of
what they should be. This test will identify those problems and takes only minutes.
Water in tube Pinched tube
1. Press [Exit] and then [Time Average] until “4s” appears.
2. Press [Mode] until both channels display pressure (in Pascals).
3. Connect the yellow tube between the red and yellow ports on the gauge.
4. If the readings are within 2% and don’t drop rapidly, the yellow tube is not blocked or
leaking and the gauge is accurate.
5. Disconnect the yellow tube and connect the Blue tube from Blue to Green ports to check
that tube and the negative side of the gauge.
6. Disconnect the Blue tube and connect the Green tube from the Green port to the Red Port
to check that tube and the negative versus positive calibration of the gauge.
If both channels don’t display the same pressure or the pressure drops rapidly the tubes are
blocked or leaking. Water can be whipped or blown out of tubes and crimped tubes can be adjusted.
If the readings are different, either one tube is blocked or the gauge is faulty. Try another tube to see if
it’s the tube or the gauge. Check each tube separately. If differences on the gauge persist with different
tubes connected, repeat the test against another gauge. Only then should a gauge return be
considered.
Pressure dropping to zero in 10 seconds or less indicates a leak somewhere; try another tube and try the
same tube on a different port to see which piece is faulty, the tube or the gauge. If the tube end is
damaged, slice 1/8 inch off the tube and try again.
The tubes have now all been checked, removing that major source of error.
11.3 Field Check the DucTester as a system
This check will ensure that the DucTester is connected properly, and will ensure that the measured
results for flow are within 10% of the true value when using the DucTester as a system with Flex Duct.
The flow verification plate is optional equipment, since a temporary one can be easily manufactured
using thin, solid, cardboard with a 4" x 4 5/8" square hole (18.6 sq in) cut in the center. If making your
own, a 1/4 inch diameter hole should be made in one corner of the plate, as far away from the larger
hole as possible, into which the blue tube can be inserted.