TrueZONE
APPLICATION
®
The TrueZONE
Bypass constant pressure regulating damper
(CPRD) is a round static pressure relief damper. It is used in
forced-air bypass applications to relieve excess static
pressure when some of the zone dampers are closed. The
damper is installed in a duct that delivers air to the return or a
dump zone. The damper automatically opens and closes to
maintain a desired static pressure.
The CPRD uses a calibrated spring to regulate the bypass air
accurately when any number or combination of zones is
calling. Conventional, weighted arm, bypass dampers may
operate properly when one zone is calling; however, when
different combinations of zones are calling, they bypass too
much or too little. This can cause callbacks when
homeowners complain of air noise.
Selecting the Correct CPRD
1. Size the bypass damper by subtracting the cfm of the
smallest zone from the cfm of the system.
2. Consult Table 1 to determine the CPRD to use.
3. Example:
Bypass CFM = Total System CFM - Smallest Zone CFM
DIMENSIONS
Regulator
A
Model
in
mm
CPRD8 8
203.2
9.65
CPRD10 10
254
11.42
CPRD12 12
305
13.18
CPRD14 14
355
14.96
®
Bypass (CPRD)
E
Damper
Table 2. CPRD Dimensions.
B
C
in
mm
in
mm
245
1.50
38
290
1.50
38
235
1.50
38
380
1.50
38
INSTALLATION INSTRUCTIONS
SPECIFICATIONS
Construction:
Galvanized steel, see Table 2
Temperature Range:
Ambient: 0F–165F (-17C–73C)
Storage: 30F–150F (-1C– 65C)
Table 1. Damper Sizing
Bypass
Damper
CPRD8
CPR8
CPRD10
CPR10
CPRD12
CPR12
CPRD14
CPR14
D
C
A
D
E
in
mm
in
mm
11.54
292.84 4.65
118
13.50
343
4.65
118
15.47
392.84 4.65
118
17.36
441
4.65
118
Replacement
Regulator
Maximum Airflow
600 CFM
1000 CFM
1400 CFM
1700 CFM
B
M34207
Gauge
26
26
24
22
69-2770EFS-03