www.belimo.com
CRA24-... • en-gb • 2013-05-15 • Subject to changes
19 / 24
Technical data sheet
CRA24-..
Introduction
The CRA24-B1P is a 3-step switch without control functions or overrides.
The various operating modes are set by pressing the button on the front.
The corresponding functions are described in detail in the following.
Function overview
Supply
AC 24V / 50/60 Hz
Application
– Air volume control in the comfort zone
Operation
– Mode selection switch: COMF – MIN – MAX
– Mode indication LED: COMF – MIN – MAX
– Hidden rotary knob for setpoint adjustment: 30…70% air
1 output
– 2…10V system output: Belimo VAV controller, damper actuator
Functions
– Air volume control
Installation
Surface mounting with flush-mounted or surface-mounted connection
Air volume control
The air volume can be pre-selected and set to minimum, variable (dial: 30 … 70%) and
maximum using the push-button and the rotary knob under the controller front. This is especially
suitable for applications requiring a defined air exchange.
Settings with ZTH-GEN
The operating volumetric flow setting
min
/
max
of the VAV controllers can be modified/checked
with the help of the ZTH-GEN.
Application with damper actuator instead of
VAV controllers
Use of damper actuators is usually possible but it must still be taken into account that this
application cannot detect and regulate pressure changes in the air duct system (pre-
pressure-dependent operation).
Type: LM24A-MF / NM24A-MF
The MIN/MAX levels of the MF actuator can be programmed with the ZTH-GEN service tool or
the Belimo PC-Tool and then be loaded in L/NM24A-MF.
Note
The MIN / MAX levels
cannot
be changed when
using an -SR standard actuator (mode 0 … 10V),
e.g. LM24A-SR!
Operating mode COMF (nominal ventilation)
Operating mode MIN (reduced ventilation)
Operating mode MAX (intensive ventilation)
• The air volume can be set in the range of
30…70% of the operating volume
current range
min
…
max
programmed on the VAV
controller.
Setting of the VAV controller (example):
–
min
50 m
3
/h
–
max
100 m
3
/h
– Setting range of the rotary knob: 65…85 m
3
/h
• Air volume setting:
– CRA24-B1P → Potentiometer under the front
cover
• The connected VAV units are set to the
minimum air volume (
min
) selected on the
controller.
• The connected VAV units are set to the
maximum air volume (
max
) selected on the
controller.
Y [V]
10
2
4.4
7.6
ao1
Y [V]
10
2
ao1
Y [V]
10
2
ao1
Max
Comfort
Min
COMF
Max
Minimum
Min
COMF
Max
Maximum
Min
COMF
Volumetric flow
max
70%
30%
min
Volumetric flow
max
min
Volumetric flow
max
min
Functions
CRA24-B1P
