Bryant 187B System Functions And Sequence Of Operation, Compressor Crankcase Heater, Start-Up

Final Wiring Check

IMPORTANT: Check factory wiring and field wire connections to ensure terminations are secured properly. Check wire routing to ensure wires are not in contact with tubing, sheet metal, etc.

Compressor Crankcase Heater

When equipped with a crankcase heater, furnish power to heater a minimum of 24 hr before starting unit. To furnish power to heater only, set thermostat to OFF and close electrical disconnect to outdoor unit.

A crankcase heater is required if refrigerant tubing is longer than 80 ft. (24.38 m). Refer to the Application Guideline and Service Manual Longline Section-Residential Split-System Air Conditioners and Heat Pumps.

Airflow Setup for Evolution Control Furnace or FE Fan Coil (communicating)

When using an Evolution User Interface, airflow is automatically selected based on equipment size. See User Interface Installation Instructions for available adjustments.

Airflow Selections (ECM Furnaces - non commu- nicating)

The ECM Furnaces provide blower operation to match the capacities of the compressor during high and low stage cooling operation. Tap selections on the furnace control board enable the installing technician to select the proper airflows for each stage of cooling. Below is a brief summary of the furnace airflow configurations

1.The Y2 call for high stage cooling energizes the “Cool” tap on the control board. The grey wire from cool tap is connec- ted to tap 5 on the motor. Refer to the furnace Product Data to find the corresponding airflow. If the airflow setting for high cooling needs to be switched from tap 5 to a different tap, jumper a connection from the cool tap to the desired tap so that the Y2 signal is communicated via the cool tap to the desired speed tap.

2.The Y1 call for low stage cooling energizes the “Fan” tap on the control board. The red wire from the fan tap is con- nected to tap 1 on the motor. Refer to the furnace Product Data to find the corresponding airflow. If the airflow setting for low cooling needs to be switched from tap 1 to a differ- ent tap, jumper a connection from the Fan tap to the desired tap so that the Y1 signal is communicated via the Fan tap to the desired speed tap. The Y1 setting will also govern the continuous fan airflow for the furnace.

Refer to the literature for the furnace for further details.

Airflow Selection for Variable Speed Furnaces (non-communicating)

The variable speed furnaces provide blower operation to match the capacities of the compressor during high and low stage cooling operation. The furnace control board allows the installing technician to select the proper airflows for each stage of cooling. Below is a summary of required adjustments. See furnace installation instructions for more details:

1.Turn SW1--5 ON for 400 CFM/ton airflow or OFF for 350 CFM/ton airflow. Factory default is OFF.

2.The A/C DIP switch setting determines airflow during high stage cooling operation. Select the A/C DIP switch setting corresponding to the available airflow shown in the furnace Installation Instructions that most closely matches the re- quired airflow shown in the air conditioning Product Data for HIGH speed.

3.The CF DIP switch setting determines airflow during low stage cooling operation. Select the CF DIP switch setting corresponding to the available airflow shown in the furnace installation instructions that most closely matches the re-

quired airflow shown in the air conditioning Product Data for LOW speed. If a higher or lower continuous fan speed is desired, the continuous fan speed can be changed using the fan switch on the thermostat. Refer to the furnace Installa- tion Instructions for details of how to use this feature.

Airflow Selection for FV4C Fan Coils (non-com- municating)

The FV4 provides high- and low-stage blower operation to match the capacities of the compressor at high- and low-stage.

To select recommended airflow, refer to the FV4C Installation Instructions. The FV4C utilizes an Easy Select control board that allows the installing technician to select proper airflows. 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 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 personal injury, equipment damage or improper operation.

S Do not overcharge system with refrigerant.

S Do not operate unit in a vacuum or at negative pressure. S Compressor 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 and observe the following:

S Front seating service valves are equipped with Schrader valves.

SYSTEM FUNCTIONS AND SEQUENCE OF OPERATION

The 180B / 187B models utilize either an Evolution 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. 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 than 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.

187B / 180B

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