Duct Connection Spigots; Duct Connection Rectangular Flanges; Optional Filter And Filter Access; Fresh Air Controller - Carrier 42NL series Installation, Operation And Maintenance Instructions

4.3.2 - Coil inlet/outlet and cooling/heating side
positions
Water inlets/outlets, all sizes : Fig. 14.
WARNING: Carefully observe the direction indicated by
the arrow on the valves, based on the valve type.

4.4 - Duct connection spigots

These are manufactured from high density plastic with a
VO fire rating, more or less equivalent to class M1 (French
standard). They are encased inside the unit. The ducts should
be fixed to these spigots using circular collars or adhesive.
Screws and rivets should not be used.
WARNING: In order to guarantee good air tightness, the
duct should overlap the whole of the spigot.
Make sure that the maximum supply air temperature does
not exceed 60°C.
Do not lift or support the unit using the spigots, place loads
on the spigots during installation or operation.

4.5 - Duct connection rectangular flanges

When connecting rectangular flanges to the inlet and the
outlet make sure that the duct is pushed closely the unit.

4.6 - Optional filter and filter access

4.6.1 - Description
The Carrier unit is fitted with G1 filter as standard. As an
option, a G3 or a M5 Filter can also be provided according
to EN 779 standard. The G3 and M5 filter are compliant to
M1 fire rating (according to NFP 92-507 standard).
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.
22

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
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.
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 inlet).
2
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, 50
3
/h.
3
/h).
3
level; in this case it is connected