Carrier Official Manual and Wiring Guide for Gas Heater Models

J4-1 or J4-4 + 24 VDC Supply Voltage
J4-2 or J4-5 (-) 4 to 20 mA Current Loop Output
to RTU-OPEN
		SPAN
		ZERO
4-20 VAC GND 0-5V
mA	or	or
	VDC	0-10V

Relative Humidity Sensor (Polarized Male Connector)

48HC

C10839

Fig. 66 - Duct Relative Humidity Sensor Typical Wiring

Humidistat: The accessory humidistat provides the RTU Open insight to the relative humidity in the space. The humidistat reads the RH level in the space and compares it to its setpoint to operate a dry contact. The humidistat is a dedicated input on the configurable input 9 and tells the RTU Open when the RH level is HIGH or LOW. The normal condition for humidity is LOW. A normally open humidistat is the factory default control for the Humidi-MiZerRoption.

To wire in the field:

SJ5-8 = 24 VAC source for dry contact S J5-7 = Signal input

Smoke Detector/Fire Shutdown (FSD) —

On 48HC units equipped with factory-installed Smoke Detector(s), the smoke detector controller implements the unit shutdown through its NC contact set connected to the unit’s CTB input. The FSD function is initiated via the smoke detector’s Alarm NO contact set. The RTU Open controller communicates the smoke detector’s tripped status to the BAS building control. See Figs. 58 and 59, the RTU Open wiring schematics.

The Fire Shutdown Switch configuration, MENU→Config→Inputs→input 5, identifies the normally open status of this input when there is no fire alarm.

Connecting Discrete Inputs —

Filter Status: The filter status accessory is a field-installed accessory. This accessory detects plugged filters. When installing this accessory, the unit must be configured for filter status by setting MENU→Config→Inputs→input 3, 5, 8, or 9 to Filter Status and normally open (N/O) or normally closed (N/C). Input 8 or 9 is recommended for easy of installation. Refer to Fig. 57 and Fig. 58 or 59 for wire terminations at J5.

Fan Status: The fan status accessory is a field-installed accessory. This accessory detects when the indoor fan is blowing air. When installing this accessory, the unit must be configured for fan status by setting MENU→Config→Inputs→input 3, 5, 8, or 9 to Fan Status and normally open (N/O) or normally closed (N/C). Input 8 or 9 is recommended for easy of installation. Refer to Fig. 57 and Fig. 58 or 59 for wire terminations at J5.

Remote Occupancy: The remote occupancy accessory is

afield-installed accessory. This accessory overrides the unoccupied mode and puts the unit in occupied mode. When installing this accessory, the unit must be configured for remote occupancy by setting MENU→Config→Inputs→input 3, 5, 8, or 9 to Remote Occupancy and normally open (N/O) or normally closed (N/C).

Also set MENU→Schedules→occupancy source to DI on/off. Input 8 or 9 is recommended for easy of installation. Refer to Fig. 57 and Table 9 for wire terminations at J5.

Power Exhaust (output): The relay used by the RTU Open board to control power exhaust is a dry contact which means it does not have 24vac. This 24vac must be connected to the relay to allow it to operate the power exhaust relay in the PE accessory. A 24vac source must be provided to J11-2 on the RTU Open control board. This can be provided by the unit’s transformer from various sources. The “R” terminal on the unit’s low voltage terminal board (LVTB) is a logical source. Refer to Fig. 57 and Fig. 58 or 59 for wire terminations at J11.

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