218 / 221
CRDS ROUND
SPRING RETURN DAMPERS
SINGLE BLADE, ROUND, SPRING RETURN DAMPERS
The CRDS series are galvanized steel, single blade dampers com-
pete with a 24 Volt, spring return motor actuator. These dampers
are shipped complete and ready for installation. The CRDS can be
installed in any position in any properly sized duct. All CRDS dampers
are rated for duct systems less than 1.0” W.C.
All CRDS dampers are typically shipped as Normally Open dampers
that are powered closed and spring returned opened. The CRDS is
also unique in that it can be field converted from powered closed to
powered open in less than a couple of minutes.
A 24 Volt AC, 50/60 Hz, spring return damper motor, powers the
CRDS. The motor powers the damper closed and spring returns the
damper open for fail-safe operation. Providing power to the damper
drives the damper closed. Removing power from the motor allows the
motor to spring back to the open position.
The 24 Volt, hysteresis, synchronous motor has been tested to over
250,000 cycles to provide long life. Even replacing the motor is a
simple less than one (1) minute change by loosening the setscrew
holding the motor onto the damper.
The CRDS motor also has a simple adjustment for setting the damper
to a minimum position. A minimum position allows for excess by-pass
air. To set a minimum position, loosen the setscrew, align the set-
screw to the minimum position label and re-tighten.
Minimum Position Adjustment
The minimum position screw can also be used to determine the
damper position. The setscrew is aligned with the position of the
damper blades. When the setscrew is in line with the duct, pointed
at the Closed on the minimum position label, the damper is actually
open. When it is hidden behind the motor and stopped against the
anti-rotation post on the motor, it is Closed or at the minimum posi-
tion.
2.5”
2.5”
10”
Diameter
7/8”
7/8”
3.25”
Dimensional Drawing
24 Volts AC
Switch
Wiring Diagram
Damper Specifications
Linkage – Direct Drive
Motor Voltage – 24 Volts AC, 50 / 60 Hz, 6.5 Watts, 7VA
Torque – 35in-oz to 55in-oz
Duct Pressure – Maximum 1.0” W.C.
Damper Dimensions and Weights
Diameter
Length
Weight
Inches MM Inches MM Lbs.
Kg
5”
127
10”
254 4lbs.
1.82
6”
152
10”
254 4lbs.
1.82
8”
203
10”
254 5lbs
2.26
9”
238
10”
254 7lbs.
3.18
10”
254
10”
292 7lbs.
3.18
12”
305
10”
336 9lbs.
4.08
14”
356
10”
394 12lbs.
5.44
16”
406
10”
451 15lbs.
6.80
18”
457
10”
482 19lbs.
9.09
www.white-rodgers.com219
TECHNICAL HELP