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Section 1. General Specification - DualAir® Unit
1.1 Basic Information
1.1.2 Description
The DualAir® combined heating and cooling unit is formed by four sections combined into a single
unitand deliveredas acomplete assemblyreadyfor installationon site.The DualAir®unit isdesigned
to be installed with the air flow from right to left as shown in Fig 1.1. Units with opposite air flow
direction are available by special order.
The four sections are as follows:-
1.1.3 Gas Fired Heater Section
The heater section is a CUHD/A 300 or the CUHD/A 380 automatic ignition unit heater and contains
the burner controls, the electrical terminal box for the system, the control relays for the operation of
the heater/cooling equipment, and the transition piece between the heater and the fan compartment.
The heater is an open flued gas fired heater of flue type B11 for vertical flue.
The On/Off heaters are Cat II 2H3+ appliances for use with Natural Gas or L.P.G. as stated on the
heater data plate (Modulating and High/Low burners are Cat I2H for use with Natural Gas only), and
are intended for indoor installation only. They must be installed and commissioned in accordance
with local regulations and the requirements of Section 3 of these Instructions.
Apermanent electricalsupply of400 volts50 Hz,threephase andNeutral isrequired forthe operation
of the heater and fan and all models must be earthed. (Note the burner operates on 230v 50 Hz taken
internally from the above supply).
1.1.4 Fan Section
The fan section houses the double-inlet, belt-drive centrifugal blower fan and three phase electric
motor. This section of the cabinet is fully insulated with foil faced glass fibre insulation.
The fan rotation is counter clockwise viewed from the control side as marked on the fan case.
1.1.5 Cooling Coil
DualAir® units can be fitted with either a DX or Chilled Water cooling coil:
1.1.5.1 DX Coil
The DX cooling coil is installed into the DualAir® unit with the two refrigerant circuits sealed ready for
site connection. There are no other refrigerant controls supplied with the coil and all refrigerant pipe-
work and controls must be supplied by the installer to suit the equipment being installed with the
condenser units.
DXcoils aredesignedfor operationat anambienttemperature of28°Cusing R22orR407C refrigerant
evaporating at 6°C.
Theinstallation ofthecooling condensersandtherefrigerantcircuitsmustbe carriedoutin accordance
with the condenser manufacturers instructions.
