Carrier 42NL series Installation, Operation And Maintenance Instructions

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

Contents

Carrier 42NL series Installation, Operation And Maintenance Instructions Manual pdf 22 page image

22ENGLISH4.3.2 - Coil inlet/outlet and cooling/heating sidepositionsWater inlets/outlets, all sizes : Fig. 14.WARNING: Carefully observe the direction indicated bythe arrow on the valves, based on the valve type.4.4 - Duct connection spigotsThese are manufactured from high density plastic with aVO fire rating, more or less equivalent to class M1 (Frenchstandard). They are encased inside the unit. The ducts shouldbe fixed to these spigots using circular collars or adhesive.Screws and rivets should not be used.WARNING: In order to guarantee good air tightness, theduct should overlap the whole of the spigot.Make sure that the maximum supply air temperature doesnot exceed 60°C.Do not lift or support the unit using the spigots, place loadson the spigots during installation or operation.4.5 - Duct connection rectangular flangesWhen connecting rectangular flanges to the inlet and theoutlet make sure that the duct is pushed closely the unit.4.6 - Optional filter and filter access4.6.1 - DescriptionThe Carrier unit is fitted with G1 filter as standard. As anoption, a G3 or a M5 Filter can also be provided accordingto EN 779 standard. The G3 and M5 filter are compliant toM1 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 returnair plenum: access is from below (trapdoor).4.6.2 - Air filter replacementAir filters should be changed regularly. Filter life dependson the rate at which the filter becomes clogged, whichdepends upon 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, check thatno T-bars will obstruct filter access and removal.4.7 - Fresh air controller4.7.1 - Fresh air controller with (adjustable) constantair volumeThe unit can be fitted with three ranges of constant andadjustable fresh air flow. The 3 ranges are 15 to 50 m3/h, 50to 100 m3/h and 100 to 180 m3/h.The diameter of the spigot housing the fresh air flowcontroller is 125 mm. The fresh air controller can be modifiedon site by unscrewing and repositioning the damper of thecontroller. See fig 17.IMPORTANT: If the unit is fitted with a return airtemperature sensor, the constant fresh air flow rate mustnot exceed 50% of the supply air flow delivered by the unitat minimum speed.NOTE: To operate correctly the constant fresh air flowcontroller requires a differential pressure in the range of60 Pa to 210 Pa.4.7.2 - Fresh air controller with variable air volumeThe unit can be equipped with a variable fresh air flowcontroller from 0 to 55 l/s (0 to 200 m3/h).This is connected to the numeric Carrier controller and canregulate the fresh air intake in two ways:• Either using a fixed rate set by the installer that canbe reconfigured as required• Or based on the CO2 level; in this case it is connectedto a CO2 sensor via the Carrier numeric controller(the CO2 sensor is located opposite the fresh air inlet).NOTE: With the variable fresh air flow controller theupstream pressure in the fresh air duct must be 180 Pa. Itis available as an accessory.4.7.3 - Fresh air filtrationIf the unit is provided without any filter or if the fresh airinlet is fitted in the base unit or in the return plenum, it isthe responsibility of the installer to check if the fresh air isfiltered beforehand.4.8 - Optional water flow control valvesThese valves are either two-way or four-way type (three-waywith integral bypass). The body of the valve is designed towithstand a 15.5 bar (1550 kPa) 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 4.8.4. - ‘‘Actuator replacement procedure’’.