Carrier 50TC installation instructions Economizer controls, Enthalpy Switch HH57AC077 Connections

When the PremierLink is configured for Thermostat Mode, these functions are not available: Fire Shutdown (FSD), Remote Occupied (RMTOCC), Compressor Safety (CMPSAFE), Supply Fan Status (SFS), and Filter Pressure Switch (FILTER).

Economizer controls —

Outdoor Air Enthalpy Control (PNO HH57AC077) -

The enthalpy control (HH57AC077) is available as a field-installed accessory to be used with the EconoMi$er2 damper system. The outdoor air enthalpy sensor is part of the enthalpy control. (The separate field-installed accessory return air enthalpy sensor (HH57AC078) is required for differential enthalpy control. See Fig. 35.)

Locate the enthalpy control in the economizer hood. Locate two GRA leads in the factory harness and connect these leads to enthalpy control sensors 2 and 3. See Fig. 35. Connect the enthalpy control power input terminals to economizer actuator power leads RED (connect to TR) and BLK (connect to TR1).

Enthalpy		CTB
		ECON
Switch
2	GRA	6
3	GRA	7

Factory Wiring Harness

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Fig. 35 - Enthalpy Switch (HH57AC077) Connections

The outdoor enthalpy changeover setpoint is set at the enthalpy controller.

Differential Enthalpy Control — Differential enthalpy control is provided by sensing and comparing the outside air and return air enthalpy conditions. Install the outdoor air enthalpy control as described above. Add and install a return air enthalpy sensor.

Return Air Enthalpy Sensor — Mount the return-air enthalpy sensor (HH57AC078) in the return-air duct. The return air sensor is wired to the enthalpy controller (HH57AC077). See Fig. 36.

ENTHALPY CONTROLLER			RED		S (OUTDOOR
					+	AIR
			BRN
A B C	TR	TR1		BLK		ENTHALPY
						SENSOR)
D	SO	+		RED
	SR	+			S (RETURN AIR
					+	ENTHALPY
	2	3				SENSOR)
		1		GRAY/ORN
LED					WIRE HARNESS
				GRAY/RED	IN UNIT
NOTES:

1.Remove factory-installed jumper across SR and + before connecting wires from return air sensor.

2.Switches shown in high outdoor air enthalpy state. Terminals 2 and 3 close on low outdoor air enthalpy relative to indoor air enthalpy.

3.Remove sensor mounted on back of control and locate in outside airstream.

C06019

Fig. 36 - Outside and Return Air Enthalpy Sensor

Wiring

To wire the return air enthalpy sensor, perform the following:

1.Use a 2-conductor, 18 or 20 AWG, twisted pair cable to connect the return air enthalpy sensor to the enthal- py controller.

2.At the enthalpy control remove the factory-installed resistor from the (SR) and (+) terminals.

3.Connect the field-supplied RED wire to (+) spade connector on the return air enthalpy sensor and the (SR+) terminal on the enthalpy controller. Connect the BLK wire to (S) spade connector on the return air enthalpy sensor and the (SR) terminal on the enthalpy controller.

NOTE: The enthalpy control must be set to the “D” setting for differential enthalpy control to work properly.

Indoor Air Quality (CO2 sensor) — The indoor air quality sensor accessory monitors space carbon dioxide (CO2) levels. This information is used to monitor IAQ levels. Several types of sensors are available, for wall mounting in the space or in return duct, with and without LCD display, and in combination with space temperature sensors. Sensors use infrared technology to measure the levels of CO2 present in the space air.

The CO2 sensors are all factory set for a range of 0 to 2000 ppm and a linear mA output of 4 to 20. Refer to the instructions supplied with the CO2 sensor for electrical requirements and terminal locations. See Fig. 37 for typical CO2 sensor wiring schematic.

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