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4 - COMPONENTS AND MAINTENANCE
4.6 - Optional filter and filter access
4.6.1 - Description
The Carrier unit is fitted with G1 filter as standard.
A G3 or M5 filter is also available as an option
G3 and M5 filters both comply with the M1 fire class.
Different filter access are available:
■ Unit without rectangular flange air inlet (plain inlet):
access is from the rear of the unit.
■ Unit with rectangular flange air inlet or with return air
plenum: access is from below (trapdoor).
4.6.2 - Air filter replacement
Air filters should be changed regularly. Filter life depends
on the rate at which the filter becomes clogged, which
depends upon the cleanliness of the working
environment.
If clogged filters are not changed they can increase the
air pressure drop, trapped dust particles may be given
off and entrained in the air supply, and the general
performance of the unit may be degraded (as the air
flow reduces).
NOTE: When installing a unit in a ceiling void, check
that no T-bars will obstruct filter access and
removal.
4.7 - Fresh air controller
4.7.1 - Fresh air controller with (adjustable)
constant air volume
The unit can be fitted with three ranges of constant and
adjustable fresh air flow. The 3 ranges are 15 to 50 m
50 to 100 m
/h and 100 to 180 m
3
The diameter of the spigot housing the fresh air flow
controller is 125 mm. The fresh air controller can be
modified on site by unscrewing and repositioning the
damper of the controller. See fig 17.
IMPORTANT: If the unit 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 constant fresh air
flow controller requires a differential pressure in the
range of 60 Pa to 210 Pa.
/h,
3
/h.
3
4.7.2 - Fresh air controller with variable air
volume
The unit can be equipped with a variable fresh air flow
controller from 0 to 55 l/s (0 to 200 m
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
to a CO
sensor via the Carrier numeric controller
2
(the CO
sensor is located opposite the fresh air
2
inlet).
NOTE: With the variable fresh air flow controller the
upstream pressure in the fresh air duct must be 180
Pa. It is available as an accessory.
4.7.3 - Fresh air filtration
If the unit is provided without any filter or if the fresh air
inlet is fitted in the base unit or in the return plenum, it
is the responsibility of the installer to check if the fresh
air is filtered beforehand.
4.8 - Optional water flow control
valves
These valves are either two-way or four-way type (three-
way with integral bypass). The body of the valve is
designed to withstand a 15.5 bar (1550 kPa) bar
operating pressure.
With this option, the couple (valve + actuator) is usually
normally closed (NC).Thus, the water flow is null in case
of power cut. To fill the installation, to equalise the water
circuits and to purge the units, the actuators must be
connected to the power supply and the valves must be
opened via the controller (thermostats or BMS).
For the replacement of these components refer to the
chapter 4.8.4. - ''Actuator replacement procedure''.
/h).
3
level; in this case it is connected
19
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