Carrier 42NH Installation, Operation And Maintenance Instructions

Also see for 42NH series: Installation, operation and maintenance instructions Original instructions

Contents

15English4.2.2 - Coil inlet/outlet and cooling/heating side positionsWater inlets/outlets, all sizes : Fig. 15.WARNING: Carefully observe the direction indicated bythe arrow on the valves, based on the valve type.4.3 - Optional filter and filter access4.3.1 - DescriptionThe Carrier unit is fitted with G1 filter as standard. As anoption, a G3 Filter can also be provided (85% gravimetricfilter) according to EN 779 standard. The G3 filter iscompliant to M1 fire rating (according to NFP 92-507standard).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 : access is frombelow (trapdoor).4.3.2 - Air filter replacementAir filters should be changed regularly. Filter life depends onthe rate at which the filter becomes clogged, which dependsupon the cleanliness of the working environment.If clogged filters are not changed they can increase the airpressure drop, trapped dust particles may be given off andentrained in the air supply, and the general performance ofthe unit may be degraded (as the air flow reduces).NOTE: When installing a unit in a ceiling void, checkthat no T-bars will obstruct filter access and removal.4.4 - Optional water flow control valvesThese valves are either two-way or four-way type (three-way with integral bypass). The body of the valve isdesigned to withstand a 16 bar operating pressure.With this option, the couple (valve + actuator) is usuallynormally closed (NC).Thus, the water flow is null in case ofpower cut. To fill the installation, to equalise the watercircuits and to purge the units, the actuators must beconnected to the power supply and the valves must beopened via the controller (thermostats or BMS).For the replacement of these components refer to thechapter ‘‘4.4.1. - Actuator replacement procedure’’.The electrothermal actuator provides an on/off control.The actuator supply is 230 V a.c.4.1.3 - Fan wiring4.1.3.1 - Multi-speeds unit with electrical box optionThis option allows the installer to connect the unit to aterminal board inside a electrical box. The electrical boxcan be opened with a screw driver.Three of the available five speeds are connected -(maximum speed = R1, minimum speed = R5). See Fig. 13.which describes wiring colors.The control box option permits changing the speed wiringwithout access to the motor. See Fig. 13.4.1.3.3. Multi-speed unit with HDb or ntC controllerWhen the unit is delivered with an HDB or a NTCcontroller, three of the five speeds are connected to aMOLEX connector: see Fig. 14 for HDB and NTC wiring.The numbering and the colors of the wiring are similar tothe electrical box (see Fig. 13).4.2 - Water coil4.2.1 - Coil removal procedureWARNING: Disconnect the power supply to the unit beforecarrying out any work on the unit.• Close the isolating valves on the manifolds.• Empty the water in the unit by opening the drainvalve (see Fig. 15)• Unscrew the union nuts to disconnect the flexiblewater pipes.• Remove the valve actuators taking care to identify thecooling and heating valves.• Disconnect the flexible condensate drain pipe held inplace by a collar (the collar is not supplied by Carrier).• Remove the two-way or four-way water flow controlvalve bodies. Depending on the unit configuration thefour-way valve coupling may be fitted with a heating/cooling changeover switch. If so, do not remove it.• Loosen the four fixing screws. Pull out the drain panand coil assembly (the drain pan remains attached tothe unit for approximately 100 mm) until the coil iscompletely detached. Then remove the coil from thedrain pan.• Replacement is by the reversal of the procedure des-cribed above. Ensure that all gaskets are changed (newgaskets fitted) and that the inlet and outlet connectionsto the coil are made correctly using an appropriatesealing compound applied to the valve body.• Bleed all air from the coil during refilling.WARNING: Take care when tightening the valve body tothe coils (15 N·m is sufficient) to ensure they are notdamaged.