Retrotec Commercial 441 and 451 DucTester - Manual (Page 55)

Page 55 of 56
©Retrotec Inc. 2015
Appendix F: Glossary
Term Definition
“ wg See “in WC”
CFM Units: Cubic feet per minute (the units of volumetric flow)
Construction Class Unless construction class is otherwise specified it means a static pressure
classification in the SMACNA HVAC-DCS. Those classifications pertain to
maximum operating pressure in the duct as follows:
0.5″ wg maximum
0.6″ to 2″ wg maximum
1.1″ to 2″ wg maximum
2.1″ to 3″ wg maximum
3.1″ to 4″ wg maximum
4.1″ to 6″ wg maximum
6.1″ to 10″ wg maximum
Control Port Ethernet port on a Retrotec fan, labeled “Control”
Depressurization The process of creating a negative pressure in the enclosure by blowing air out of it. Air is
drawn in from outside to replace it, showing up as “geysers” when checked with an air
current tester.
Digital Gauge A gauge with an electronic pressure sensor and digital display that is capable of reading in
tenths of a Pascal.
Duct Class see Pressure Class
Fan Pressure The pressure difference between the inlet side of the fan and the interior of the fan.. This
pressure can be read as “PrB” from Channel B on the gauge. It is used by the computer to
calculate the air flow rate through the Blower Door.
Fan Top Part on the fan where the fan’s tubing, Control Cable, and power connections are.
The Fan Top for the Model 200 refers to the two mounted red plates attached to the sides
of the fan. Attached behind them are Printed Circuit Boards (PCBs). In this manual, we will
refer to the “Control PCB assembly” as the one that has “Control” printed on the mounting
plate. We will refer to the “Power PCB assembly” as the one with the power switch on it,
and has “Mains Power” printed on it.
HVAC Heating Ventilating and Air conditioning.
In WC Inches of Water Column, Water Gauge, “wg and in WC are all equivalent terms. “in WC” is
used throughout this manual for consistency. This is a common unit of pressure used in the
USA although elsewhere, Pascals (Pa) are more common. One in WC = 249 Pa and is the
amount if pressure that will support a column of water for one inch of height.
Inches Of Water Column See “in WC”
Leakage A general term used to describe holes or the area of holes in in the envelope around an
enclosure.
Leakage Area This is the same as “Leakage” but expressed in sq ft or m 2 .
Leakage Class, C
l
C
L
= F (leakage rate in CFM/ 100 sq ft) divided by the Pressure in in WC to
the 0.65 Power. C
L
= F / P 0.65
Leakage Constant and Leakage Classification are equivalent terms.
Leakage Classification Same as Leakage Class
Leakage Constant Same as Leakage Class
Leakage Factor, F F is the allowable leakage in CFM/ 100 sq ft = C
L
* P 0.65
Where P is the test pressure in in WC and C
L
is the Leakage Class.
` Leadership in Energy and Environmental Design
Manual Speed Control
Knob The dial that is on a Fan Top to control fan speed