Carrier 42NH Installation, Operation And Maintenance Instructions

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

Contents

14Englishlevel the unit (Figs. 7 and 8).Adjust the hanger nuts so that the unit is inclined 0.5%towards the condensate drain pan. In the other direction(air flow direction) the unit must be perfectly level (Figs. 7and 8).Condensate drain pipe (Fig. 9): Use a flexible pipe with aninside diameter of 16 mm and provide a constant fall of20 mm/m over the whole horizontal pipe run. Install a 50mm (minimum) siphon to prevent gases and odours fromflowing back into the ceiling void.WARNING: After drain pipe connection, controlclamping of the drain pipe and be sure there is no waterleakage.If several units are connected to a common collector, a devicemust be installed (Fig. 10). Before operating the unit, ensurethat the water flows into the internal condensate drain pan bypouring some water into it. If problems are detected, checkthe drain pipe slope and look for possible obstructions. Inall cases the connection duct(s) at the unit outlet must beinsulated to prevent any condensate formation on the walls.NOTE: The pressure losses of these ducts must be compa-tible with the unit performance. The duct must be as smoothas possible. Avoid sharp bends. Check that there are noleaks or kinks, and that there is no dirt or installationdebris inside the ducts. Debris within the ducts mightdamage the fan wheel and the damper in the air diffusers.When installation is complete - i.e. when the 42NH isattached to the ceiling, air ducts are complete, watermani-folds are in position with stop valves ready on theconnection stubs, and electrical installation is prepared -then connect the water pipe (3/4’’ gas screw connector).NOTE : Each fan-coil units shall be connected withwater flexible pipes in order to avoid any damage due tovibrations.Ensure that a gasket (not supplied by Carrier) is installedbetween the screw connector and the stop valve.When all units are installed, open the stop valves on themanifolds, bleed and then pressurize the circuits. To bleedthe coils, slightly loosen the bleed screws. The installationcan then be started.NOTE: Do not switch on the power until all connectionsare made and earthed.3.3 - Removal procedureSwitch off the unit power supply at the isolator providedfor the purpose during installation (isolator not suppliedby Carrier).• Disconnect the power supply and connection cables.• Close the isolating valves on the manifolds.• Disconnect the flexible water pipes by unscrewing thegas connectors.WARNING: Since the flexible water pipes do not havedrain valves, a receiver must be provided to allow thecooling coil to be drained.• Disconnect the supply air ducts.• Disconnect the flexible condensate drain pipe. Drainthe siphon into a suitable vessel.• Support the unit lightly and release it by unscrewingthe four nuts on the threaded hangers. Lower the unitcarefully.4 - COMPONENTS AND MAINTENANCE4.1 - Fan motor assembly4.1.1 - Fan assembly removal procedureWARNING: Disconnect the power supply to the unit beforecarrying out any work on the unit.Identify and note the wired fan speeds. If the fan developsa fault the whole assembly must be removed and replaced(Fig. 11).• Remove the filter.• Remove the fan access panel.• Disconnect the fan assembly power supply cables(power and control wiring for variable-speed motor).• If necessary remove the controller (fixed with screws)to gain access to the maintenance screws of the panelsupporting the fan.• The fan assembly and its panel are held in place byfour torx screws (T20). Remove these screws and slidethe assembly down.• Remove the fan motor assembly.NOTE: Be careful not to touch the fan blades duringthe removal process to avoid unbalancing the fans.• For units with the electric heater option, disconnectthe power supply cable to the heater. Withdraw thecable through the cable gland.• Unscrew the electric heaters.• Replacement of the fan motor assembly is by thereversal of the above procedure.WARNING: The electrical connections to the fan motormust be made in accordance with the labels on theconnector block.4.1.2 - Capacitor replacement procedure• Disconnect the power supply to the unit before carryingany work on the unit.• Remove the filter.• Remove the fan motor assembly access panel.• Remove the capacitor that is attached to the motorchassis assembly.• Disconnect the capacitor by withdrawing the flat spadeconnectors from the back of the capacitor.• Replacement of the capacitor assembly is by the reversalof the above procedure.