Retrotec DucTester 341 - Manual (Page 57)

Page 57 of 83
©Retrotec Inc. 2014
12.4 Measure with a DucTester on the air handler cabinet
Measure the supply plenum pressure using the Static Pressure Probe supplied with each DucTester. Put
the end of the blue tube with the probe into the supply plenum, connect the other end of the blue tube
to the “Input A” (blue) port and read the pressure from Channel A on the gauge.
Attach the DucTester to the cabinet using cardboard and tape so it is blowing into the air handler on the
Open range. Set Pressure to the previously measured value. Press
[Set Pressure] and enter the
previously measured supply plenum pressure. Press the [@] key until the supply plenum pressure
appears as “CFM@”. Read the “CFM@” result on the gauge.
For example, if the pressure in the supply plenum is 70 Pa, Press [Set Pressure] , [70] , [Enter] to get the
DucTester to recreate the original pressure in the plenum. Press the [@] key until “CFM @ 70 Pa”
appears on the display. The CFM result displayed will be corrected for what the airflow will be during
normal operation (the supply pressure in the plenum measured at the start of the test).
If “---“appears the pressure in the plenum is too high to get an accurate reading. Repeat the procedure
but move the Static Pressure Probe to measure the pressure farther away from the air handler.
12.5 Measure with a gauge and a flow grid
A unique Retrotec feature allows the gauge to be used with flow grids from other manufacturers.
Measure the supply plenum pressure using the Static Pressure Probe supplied with each DucTester. Put
the end of the blue tube with the probe into the supply plenum, connect the other end of the blue tube
to the “Input A” (blue) port and read the pressure from Channel A on the gauge.
Install the flow grid into the filter slot per manufacturer instructions, which includes connecting the
green and yellow tubes to the gauge. Press
[Set Pressure] and enter the just measured supply plenum
pressure, even though the gauge is not controlling anything. Press the [@] key until the supply plenum
pressure appears as “CFM@”. Read the “CFM@” result on the gauge.
For example, if the pressure in the supply plenum is 70 Pa, Press [Set Pressure] , [70] , [Set] to get the
DucTester to recreate the original pressure in the plenum. Press the [@] key until “CFM @ 70 Pa”
appears on the display. The CFM result displayed will be corrected for what the airflow will be during
normal operation (the supply pressure in the plenum measured at the start of the test).
If “---“appears on the display as the result, the pressure in the plenum is too high to get an accurate
reading. Remove the probe from the plenum, read the CFM on Channel B and use the table that came
with the flow grid to correct the flow to match the pressure measured in the supply.
12.6 Measure using air handler blower curves
If air handler blower curves are available, they will show system flow versus pressure across the air
handler, from supply to return. To determine the pressure across the air handler, measure the pressure
between the air handler cabinet on the return side and the supply plenum.
You may need the results in units other than Pascals, often inches WC, depending on what pressure
units are used on the air handler blower curves. Do this by pressing [Settings] [Result to be Displayed]
and toggle the [Pressure] button until the desired units is displayed, such as inches of Water Column (in
WC).
You could manually convert Pascal readings by dividing the pressure in Pascals by 250 for inches Water
Column.