Carrier SINGLE PACKAGE ROOFTOP 48HC Installation Instructions Manual

Also see for 48TC*D: Service and maintenance instructions Installation instructions

32Economizer ControlsIndoor Air Quality (CO 2 ) Sensor —The indoor air quality sensor accessory monitors spacecarbon dioxide (CO2 ) levels. This information is used tomonitor IAQ levels. Several types of sensors are available,for wall mounting in the space or in return duct, with andwithout LCD display, and in combination with spacetemperature sensors. Sensors use infrared technology tomeasure the levels of CO2 present in the space air.The CO2 sensors are all factory set for a range of 0 to2000 ppm and a linear mA output of 4 to 20. Refer to theinstructions supplied with the CO2 sensor for electricalrequirements and terminal locations. See Fig. 46 fortypical CO2 sensor wiring schematic.8 7 6 5 4 3 2 12 1H G 24 VACOR24 VDCNC ALARMRELAYCONTACTSCOMNO }0-10VDCSIG COM4-20mA++-+ -J3 J4C08635Fig. 46 -- Indoor/Outdoor Air Quality (CO 2 ) Sensor(33ZCSENCO2) -- Typical Wiring DiagramTo accurately monitor the quality of the air in theconditioned air space, locate the sensor near a return--airgrille (if present) so it senses the concentration of CO2leaving the space. The sensor should be mounted in alocation to avoid direct breath contact.Do not mount the IAQ sensor in drafty areas such as nearsupply ducts, open windows, fans, or over heat sources.Allow at least 3 ft (0.9 m) between the sensor and anycorner. Avoid mounting the sensor where it is influencedby the supply air; the sensor gives inaccurate readings ifthe supply air is blown directly onto the sensor or if thesupply air does not have a chance to mix with the room airbefore it is drawn into the return airstream.Wiring the Indoor Air Quality Sensor: For each sensor,use two 2--conductor 18 AWG (American Wire Gage)twisted--pair cables (unshielded) to connect the separateisolated 24 vac power source to the sensor and to connectthe sensor to the control board terminals.To connect the sensor to the control, identify the positive(4 to 20 mA) and ground (SIG COM) terminals on thesensor. See Fig. 46. Connect the 4--20 mA terminal toterminal TB3--9 and connect the SIG COM terminal toterminal TB3--11. See Fig. 47.J4J5-5J5-3911TB3TB3IAQ Sensor PL24 VAC4-20mASIG COMC11156Fig. 47 -- Indoor CO 2 Sensor (33ZCSENCO2)ConnectionsRefer to Form 33CS--67SI, PremierLink Installation,Start--up, and Configuration Instructions, for detailedconfiguration information.Outdoor Air Quality Sensor (PNO 33ZCSENCO2 plusweatherproof enclosure) —The outdoor air CO2 sensor is designed to monitor carbondioxide (CO2 ) levels in the outside ventilation air andinterface with the ventilation damper in an HVAC system.The OAQ sensor is packaged with an outdoor cover. SeeFig. 48. The outdoor air CO2 sensor must be located in theeconomizer outside air hood.COVER REMOVED SIDE VIEWC07135Fig. 48 -- Outdoor Air Quality Sensor CoverWiring the Outdoor Air CO 2 Sensor: A dedicatedpower supply is required for this sensor. A two--wire cableis required to wire the dedicated power supply for thesensor. The two wires should be connected to the powersupply and terminals 1 and 2.To connect the sensor to the control, identify the positive(4 to 20 mA) and ground (SIG COM) terminals on theOAQ sensor. See Fig. 46. Connect the 4 to 20 mAterminal to the TB3--13 terminal of the 48HC. Connect theSIG COM terminal to the TB3--11 terminal of the 48HC.See Fig. 49.48HC