Carrier 25HPA6 Install Accessories, Start-Up, System Functions And Sequence Of Operation

Airflow Selection for FV4C Fan Coils Using Non-Communicating (Non-Infinity) Thermostats

The FV4C provides high- and low-stage blower operation to match the capacities of compressor at high- and low-stage. To select recommended airflow, refer to FV4C Installation Instructions. The FV4C utilizes an Easy Select control board that allows the installing technician to select proper airflows. For adjustments to control board, select appropriate HP SIZE and CFM ADJUST setting. This fan coil has an adjustable blower off delay factory set at 90 sec for high- and low-stage blower operation.

When using a communicating (Infinity) control, dipswitch adjustments are not necessary. Airflows are determined by Infinity Control setup. The fan coil is the FE4A.

For other combinations of equipment consult Product Data Digest.

Install Accessories

Refer to the individual instructions packaged with kits or accessories when installing.

When using a communicating control with the fan coil or the furnace, dip switch adjustments are not necessary. The outdoor unit configuration and the indoor airflows are determined by communicating control setup.

Start-Up

!CAUTION

UNIT OPERATION AND SAFETY HAZARD

Failure to follow this caution may result in minor personal injury, equipment damage or improper operation.

Observe the following:

1.Do not overcharge system with refrigerant.

2.Do not operate unit in a vacuum or at negative pressure.

3.Do not disable low pressure switch

4.Dome temperatures may be hot.

!CAUTION

PERSONAL INJURY HAZARD

Failure to follow this caution may result in personal injury.

Wear safety glasses, protective clothing, and gloves when handling refrigerant.

!CAUTION

ENVIRONMENTAL HAZARD

Failure to follow this caution may result in environmental damage.

Federal regulations require that you do not vent refrigerant to the atmosphere. Recover during system repair or final unit disposal.

Follow these steps to properly start up the system:

1.After system is evacuated, fully open liquid and vapor ser- vice valves.

2.Close electrical disconnects to energize system.

3.Set room thermostat or User Interface at desired temperat- ure. Be sure set point is below indoor ambient temperature and is set low enough to energize desired stage.

4.Set room thermostat or User Interface to HEAT or COOL and fan control to AUTO or ON, as desired. Wait for appro- priate time delay(s). Operate unit for 15 minutes. Check re- frigerant charge.

NOTE: Systems using only a non-communicating (non-Infinity) thermostat, Carrier electronic thermostats are equipped with a 15-minute staging timer. This timer prevents the two-stage system from operating at high stage until unit has been operating in low stage for 15 minutes, unless there is at least a ±5°F (±2.8°C) difference between room temperature and thermostat set point. To force high stage (after a minimum of 2 minutes in low stage), adjust the set point at least ±5°F (±2.8°C) below room ambient.

System Functions And Sequence Of Operation

The 25HPA6 models utilize either an Infinity Communicating User Interface or a 2-stage cooling indoor thermostat. With a call for first stage cooling, the outdoor fan and low-stage compressor are energized. If low-stage cannot satisfy cooling demand, high-stage is energized by the second stage of indoor thermostat. After second stage is satisfied, the unit returns to low-stage operation until first stage is satisfied or until second stage is required again.

When both first stage and second stage cooling are satisfied, the compressor will shut off. Therefore, with first stage of cooling Y1 is powered on; and with second stage of cooling Y1 and Y2 are powered on. When a 2-stage unit is operating at low-stage, system vapor (suction) pressure will be higher than a standard single-stage system or high-stage operation.

When the outdoor ambient is more the 100_F (37.8_C), the outdoor fan will continue to run for one minute after compressor shuts off. This reduces pressure differential for easier starting in the next cycle.

With non-communicating (non-Infinity) systems, with first stage of cooling, Y1 and O are powered on; and with second stage of cooling, Y1, Y2, and O are on. For these systems, with first stage of heating Y1 is on and for second stage of heating, Y1 and Y2 are on. When the reversing valve is energized, O is powered on.

Communication and Status Function Lights

For Infinity Control only, Green communications (COMM) Light

A green LED (COMM light) on the outdoor board (see Fig. 6) indicates successful communication with the other system products. The green LED will remain OFF until communication is established. Once a valid command is received, the green LED will turn ON continuously. If no communication is received within 2 minutes, the LED will be turned OFF until the next valid communication.

Amber Status Light

An amber colored STATUS light is used to display the operation mode and fault codes as specified in the troubleshooting section. See Table 4 for codes and definitions.

NOTE: Only one code will be displayed on the outdoor unit control board (the most recent, with the highest priority).

Crankcase Heater Operation

The crankcase heater is energized during off cycle below 65°F (18.33°C).

Outdoor Fan Motor Operation

The outdoor unit control energizes outdoor fan anytime compressor is operating, except for defrost or low-ambient cooling. The outdoor fan remains energized if a pressure switch or compressor overload should open. Outdoor fan motor will continue to operate for one minute after the compressor shuts off when the outdoor ambient is greater than or equal to 100°F (37.78°C). This reduces pressure differential for easier starting on next cycle.

The outdoor fan motor is a PSC type. A fan relay on the control board turns the fan off and on by opening and closing a high voltage circuit to the motor. It does not change speeds between low and high stage operation.

25HPA6

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