Carrier 50HCQA04-06, Installation Instructions Manual

43

4. Press the   (Menu Up/Exit) button to complete the action

and return to the previous menu.

NOTE: If the alarm still exists after clearing it, it is redisplayed

within 5 seconds.
SMOKE DETECTORS
Smoke detectors are available as factory-installed options on

50HCQ models. Smoke detectors may be specified for Supply

Air only or for Return Air without or with economizer, or in

combination of Supply Air and Return Air. Return Air smoke

detectors are arranged for vertical return configurations only. All

components necessary for operation are factory-provided and

mounted. The unit is factory-configured for immediate smoke

detector shutdown operation; additional wiring or modifications

to unit terminal board may be necessary to complete the unit and

smoke detector configuration to meet project requirements.
Units equipped with factory-optional Return Air smoke detec-

tors require a relocation of the sensor module at unit installa-

tion. See Fig. 51 for the as-shipped location.

Completing Return Air Smoke Sensor Installation

1. Unscrew the two screws holding the Return Air Smoke

Detector assembly. See Fig. 52, Step 1. Save the screws.

2. Turn the assembly 90 degrees and then rotate end to end.

Make sure that the elbow fitting is pointing down. See Fig.

52, Step 2.

3. Screw the sensor and detector plate into its operating posi-

tion using screws from Step 1. See Fig. 52, Step 3. 

4. Connect the flexible tube on the sampling inlet to the sam-

pling tube on the basepan.

Fig. 51 — Return Air Smoke Detector,

Shipping Position

Additional Application Data

Refer to the application data document “Factory Installed

Smoke Detectors for Small and Medium Rooftop Units 2 to 25

Tons” for discussions on additional control features of these

smoke detectors including multiple unit coordination.
RTU OPEN CONTROLLER (FACTORY OPTION)
For details on operating 50HCQ units equipped with the facto-

ry-installed RTU Open controller option, refer to the Factory-

Installed Option RTU Open Multi-Protocol Controller Con-

trols, Start-Up, Operation and Troubleshooting manual.
CONTROLLER OPTIONS

Low Ambient

If the unit comes with Electro-Mechanical (EM) control, then

no adjustment is necessary. 
If the unit comes with the RTU Open control option, then refer

to its installation control manual for details on adjusting “Cool-

ing Lock-Out” setting and configure for the specific job re-

quirements.

Step 12 — Adjust Factory-Installed Options

SMOKE DETECTORS
Smoke detector(s) will be connected at the Controls Connec-

tions Board, at terminals marked “Smoke Shutdown.” Cut

jumper JMP 3 when ready to energize unit.
ECONOMI$ER IV OCCUPANCY SWITCH
See Fig. 53 for general EconoMi$er IV wiring. External occu-

pancy control is managed through a connection on the Controls

Connections Board.
If external occupancy control is desired, connect a time clock

or remotely controlled switch (closed for Occupied, open for

Unoccupied sequence) at terminals marked OCCUPANCY.

Cut jumper JMP 2 to complete the installation.

Step 13 — Install Accessories

Available accessories include:
• Roof  curb

• Thru-base connection kit (must be installed before unit is

set on curb)

• Electric heaters and single-point connection kits

• Manual outside air damper

• Two-position motorized outside air damper

• EconoMi$er

®

 IV (with control)

• EconoMi$er2 (without control/for external signal)

• Power Exhaust

• Differential dry-bulb sensor (EconoMi$er IV)

• Outdoor enthalpy sensor

• Differential enthalpy sensor

• CO

2

 sensor

• Smoke Detector (Return Air and/or Supply Air)

• Louvered hail guard

• Motormaster

®

 head pressure controls

• Phase monitor control
Refer to separate installation instructions for information on in-

stalling these accessories.

RETURN AIR 

S

MOKE DETECTOR

(A

S

S

HIPPED)