4.5 - Constant-volume fresh air controller
4.5.1 - Constant-volume fresh air controller
The 42BJ ICM can be fitted with a constant fresh air flow controller
allowing the introduction of fresh air and the air change rate to be
controlled.
The following range of fresh air controllers is available:
Option a:
8.3 l/s (30 m
3
/h) (-10%; +20%)
Option b:
16.6-44.4 l/s (60-160 m
3
/h) (-10%; +20%)
Options a and b:
the diameter of the spigot housing the fresh air
flow controller is 125 mm.
The 16.6 1/s (60 m
3
/h) fresh air controller may be modified on site
by relocating or removing two plastic restrictors in order to increase
the maximum constant fresh air flow capacity to 44.4 1/s (160
m
3
/h). A label on the 42BJ ICM shows how to adjust the two plastic
restrictors (Fig. 11).
Modification procedure
-
Disconnect the fresh air duct from the spigot on the unit.
-
Remove or reposition the two plastic restrictors, following the
fresh air flow controller.
-
Reconnect the fresh air duct to the spigot.
IMPORTANT: If the 42BJ ICM is fitted with a return air
temperature sensor, the constant fresh air flow rate must not
exceed 50% of the supply air flow delivered by the unit at
minimum speed.
NOTE: To operate correctly, the 8.3 l/s (30 m
3
/h) constant fresh
air flow controller requires a differential pressure in the range
50 Pa to 200 Pa. The 16.6 l/s (60 m
3
/h) constant fresh air
controller requires a differential pressure in the range 70 to
200 Pa.
4.5.2 - Fresh air controller with variable air volume
The 42BJ ICM can be equipped with an optional variable fresh air
flow controller from 0 to 55 l/s (0 to 200 m
3
/h).
This is connected to the numeric Carrier controller and can regulate
the fresh air intake in two ways:
-
either using a fixed rate set by the installer that can be
reconfigured as required
-
or based on the CO
2
level; in this case it is connected to a
CO
2
sensor via the Carrier numeric controller.
NOTE: With the variable fresh air flow controller the upstream
pressure in the fresh air duct must be 180 Pa.
4.6 -
Optional water flow control valves
These valves are two-way or three-way type, with a body designed
to withstand a 16 bar operating pressure.
4.6.1 -
Thermoelectric actuator (on/off)
The actuator is a 230 V a.c. on/off type.
NOTE: The thermoelectric actuator is supplied in the normally
closed position for both the two- and the three-way valve (way
A-AB closed for a three-way valve).
To enable the installation to be filled with water, the water circuits
to be equalised and the units to be purged, the actuators must be
connected to the power supply to open the valves via a command
from the wall thermostats or from the BMS.
4.6.2 - Actuator replacement procedure
The actuators on both the chilled water and the hot water valves
may be replaced if either develops a fault.
-
Disconnect the power supply to the unit before carrying out
any work on a unit.
-
Disconnect the actuator power supply cable equipped with
a quick connector.
-
Uncouple the faulty actuator. Refitting is by the reversal of
the procedure described above.
WARNING: Ensure that the actuator is firmly screwed to the
valve body (maximum torque 15 N·m).
4.6.3 - Valve body replacement procedure
-
Disconnect the power supply before carrying out any work
on a unit.
-
Close the isolating valves on the manifolds.
-
Unscrew the union nuts to disconnect the flexible water pipes.
-
Remove the valve actuators taking care to identify the cooling
and heating valves.
-
Remove the two-way or three-way water flow control valve
bodies. Depending how the unit is configured, the three-way
valve coupling may be fitted with a heating/cooling
changeover switch, if so do not remove it.
-
Fit the new valve body to the coil (fit new gaskets).
-
Refit the valve actuators taking care to ensure that they are
correctly fixed to the valve body.
-
Reconnect the flexible water pipes by tightening the union
nuts. Retighten all the water connections and ensure that all
gaskets have been changed and correctly fitted (maximum
torque 15 N·m).
-
Open the isolating valves on the manifolds and purge all air
from the system.
-
Check that there are no leaks and reconnect the power to
the unit.
WARNING: When replacing a valve always ensure that the
direction of flow through the valve is as shown by the arrow
on the valve body. If the direction of flow is wrong, the valve
body will deteriorate rapidly.
4.7 - Replacing the electric heater (Fig. 13)
CAUTION: It is vital to disconnect the ICM from the general
power supply before carrying out any work on the electric
heater.
If the electric heater develops a fault, the assembly must be
removed and replaced; the fan unit will have to be removed to
make this possible.
a) Refer to the fan removal procedure.
b) Remove the support assembly and the electric heater by
removing the two screws.
c) Disconnect the electric heater cable (3 wires terminating in flat
spade connectors).
d) Release the heater mounting and remove the heater.
e) Replace the defective heater.
f) Use the above procedure in reverse to install the new heater
and to reinstall the fan motor assembly.
WARNING
-
Do not touch the heater elements when the heater is
switched on.
-
Do not touch the fan wheel during the removal and re-
assembly process.
4 - COMPONENTS
12
