Carrier 50PCH specifications Pre-Start-Up

Wiring a Supply Air Temperature (SAT) Sensor — The SAT sensor is required for reheat applications.

If the cable used to wire the SAT sensor to the controller will be less than 100 ft, an unshielded 22 AWG (American Wire Gage) cable should be used. If the cable will be greater than 100 ft, a shield 22 AWG cable should be used. The cable should have a maximum length of 500 ft.

To wire the SAT sensor to the controller:

1.Wire the sensor to the controller. See Fig. 18-20.

2.Verify that the Enable SAT jumper is on.

3.Verify that the Enable SAT and Remote jumper is in the left position.

Wiring an Indoor Air Quality (IAQ) Sensor — An IAQ sensor monitors CO2 levels. The WSHP Open controller uses this information to adjust the outside-air dampers to provide proper ventilation. An IAQ sensor can be wall-mounted or mounted in a return air duct. (Duct installation requires an aspi- rator box assembly.)

The sensor has a range of 0 to 2000 ppm and a linear 4 to

20 mA output. This is converted to 1 to 5 vdc by a 250-ohm, 1/4 watt, 2% tolerance resistor connected across the zone con- troller’s IAQ input terminals.

NOTE: Do not use a relative humidity sensor and CO2 sensor on the same zone controller if both sensors are powered off the board. If sensors are externally powered, both sensors may be used on the same zone controller.

If the cable used to wire the IAQ sensor to the controller will be less than 100 ft, an unshielded 22 AWG (American Wire Gage) cable should be used. If the cable will be greater than 100 ft, a shield 22 AWG cable should be used. The cable should have a maximum length of 500 ft.

To wire the IAQ sensor to the controller:

1.Wire the sensor to the controller. See Fig. 18-20.

2.Install a field-supplied 250-ohm, 1/4 watt, 2% tolerance resistor across the controller’s RH/IAQ and Gnd terminals.

3.Verify the the RH/IAQ jumper is set to 0 to 5-vdc.

Wiring a Relative Humidity (RH) Sensor — The RH sensor is used for zone humidity control (dehumidification) if the WSHP unit has a dehumidification device. If not, the sensor only monitors humidity.

NOTE: Do not use a relative humidity sensor and CO2 sensor on the same zone controller if both sensors are powered off the board. If sensors are externally powered, both sensors may be used on the same zone controller.

If the cable used to wire the RH sensor to the controller will be less than 100 ft, an unshielded 22 AWG (American Wire Gage) cable should be used. If the cable will be greater than 100 ft, a shield 22 AWG cable should be used. The cable should have a maximum length of 500 ft.

To wire the RH sensor to the controller:

1.Strip the outer jacket from the cable for at least 4 inches.

2.Strip 1/4 in. of insulation from each wire.

3.Wire the sensor to the controller.

PRE-START-UP

System Checkout — When the installation is complete, follow the system checkout procedure outlined below before starting up the system. Be sure:

1.Voltage is within the utilization range specifications of the unit compressor and fan motor and voltage is balanced for 3 phase units.

2.Fuses, breakers and wire are correct size.

3.Low voltage wiring is complete.

4.Piping and system flushing is complete.

5.Air is purged from closed loop system.

6.System is balanced as required. Monitor if necessary.

7.Isolation valves are open.

8.Water control valves or loop pumps are wired.

9.Condensate line is open and correctly pitched.

10.Transformer switched to lower voltage tap if necessary.

11.Blower rotates freely — shipping support is removed.

12.Blower speed is on correct setting.

13.Air filter is clean and in position.

14.Service/access panels are in place.

15.Return-air temperature is between 40 to 80 F heating and 50 to 110 F cooling.

16.Air coil is clean.

17.Control field-selected settings are correct.

AIR COIL — To obtain maximum performance, clean the air coil before starting the unit. A ten percent solution of dish- washer detergent and water is recommended for both sides of the coil. Rinse thoroughly with water.

PSC (Permanent Split Capacitor) Blower Speed Selection — The PSC blower fan speed can be changed by moving the blue wire on the fan motor terminal block to the desired speed as shown in Fig. 28. The 50PC units are designed to deliver rated airflow at nominal static (0.15 in. wg) on medium speed (factory setting) and rated airflow at a higher static (0.4 to 0.5 in. wg) on high speed for applications where higher static is required. Low speed will deliver approx- imately 85% of rated airflow at 0.10 in. wg. An optional ‘high static’ blower is available by using the special option code in the model nomenclature.

NOTE: Blower performance is shown in Tables 8-10.

CONNECT THE BLUE WIRE TO:

H FOR HIGH SPEED FAN

M FOR MEDIUM SPEED FAN

L FOR LOW SPEED FAN

BLU

MEDIUM FACTORY SETTING

H M L a50-6805ef

FAN MOTOR

Fig. 28 — Blower Speed Selection

Table 8 — 50PCV Blower Performance with

Wet Coil

COIL FACE VELOCITY	WET COIL REDUCTION
(fpm)	(in. wg)
200	0.030
250	0.055
300	0.080
350	0.100
400	0.120
450	0.140
500	0.160

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