Airflow Selections for 187B / 286B / 180B /289B Using Non-Communicating (Non-Evolution) Thermostats
Airflow Selection for 315AAV/355AAV Furnaces
The 315AAV/355AAV variable-speed furnaces provide high-and low-stage blower operation to match the capacities of the compressor at high and low stages. To select the recommended airflow and for adjustments to the manual switches labeled SW1-5, AC, and CF on the control board, refer to the furnace Installation Instructions. The 315AAV/355AAV utilizes a control center that allows the installing technician to select the proper airflows. The HP switch determines the airflow during high-stage compressor operation. Airflow for high- and low-stage can be calculated at either 350 CFM per ton or 400 CFM per ton, based on the positions of SW1-5.
When using communicating (Evolution) control, dipswitch adjustments are not necessary on furnaces. Airflows are determined by Evolution Control setup.
Airflow Selection for FV4 Fan Coils for 180B, 187B, 286B, 289B Using Non-Communicating (Non-Evolution) Thermostats
The FV4 provides high- and low-stage blower operation to match the capacities of compressor at high- and low-stage. To select recommended airflow, refer to FV4 Installation Instructions. The FV4 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.
For other combinations of equipment consult Product Data Digest.
GENERAL INFORMATION
Low Ambient Cooling
When this unit is operating below 55_F outdoor temperature, provisions must be made for low ambient operation.
Evolution Controlled low ambient cooling:
This unit is capable of low ambient cooling without a kit ONLY when using Evolution control. A low ambient kit is not required, and the outdoor fan motor does not need to be replaced for Evolution controlled low ambient operation. The Evolution Control provides an automatic evaporator coil freeze protection algorithm that eliminates the need for an evaporator freeze thermostat. Low ambient cooling must be enabled in the User Interface set up. Fan may not begin to cycle until about 40_F OAT. Fan will cycle based on coil and outdoor air temperature.
Evolution controlled low ambient mode operates as follows:
SFan is OFF when outdoor coil temp is < (outdoor air temperature + 3_F) or outdoor fan has been ON for 30 minutes. (Fan is turned off to allow refrigerant system to stabilize.)
SFan is ON when outdoor coil temp > (outdoor air temperature + 25_F) or outdoor coil temp > 80_F or if outdoor fan has been OFF for 30 minutes. (Fan is turned on to allow refrigerant system to stabilize.)
SLow pressure switch is ignored for first 3 minutes during low ambient start up. After 3 minutes, if LPS trips, then outdoor fan motor is turned off for 10 minutes, with the compressor running. If LPS closes within 10 minutes then cooling continues with the outdoor fan cycling per the coil temperature routine listed above for the remainder of the cooling cycle. If the LPS does not close within 10 minutes, then the normal LPS trip response (shut down cooling operation and generate LPS trip error) will occur.
For 180B/289B models, the PWM output for both high and low stage equals the value for low stage operation below 55_F.
Defrost
This control offers 5 possible defrost interval times: 30, 60, 90, 120 minutes, or AUTO.
With non-communicating thermostats, these are selected by dip switches on the unit control board. With communicating thermostats, the Evolution Control User Interface. The Evolution Control selection overrides the control board dip switch settings.
AUTO defrost adjusts the defrost interval time based on the last defrost time as follows:
SWhen defrost time <3 minutes, the next defrost interval=120 minutes.
SWhen defrost time 3-5 minutes, the next defrost interval=90 minutes.
SWhen defrost time 5-7 minutes, the next defrost interval=60 minutes.
SWhen defrost time >7 minutes, the next defrost interval=30 minutes.
The control board accumulates compressor run time. As the accumulated run time approaches the selected defrost interval time, the control board monitors the coil temperature sensor for a defrost demand. If a defrost demand exists, a defrost cycle will be initiated at the end of the selected time interval. A defrost demand exists when the coil temperature is at or below 32_F for 4 minutes during the interval.
The defrost cycle is terminated when the coil temperature reaches 65_F or 10 minutes has passed.
On 286B models, defrost will occur in low- or high-stage as demanded by the thermostat or User Interface regardless of OAT
On 289B models, when OAT is >25_F (-3.9_C), defrost will occur in low- or high-stage as demanded by the thermostat or User Interface.
On 289B models, if OAT is ≤25_F (-3.9_C), defrost will occur in high-stage only, regardless of thermostat or User Interface demand, and will terminate at 50_F (10_C) coil temperature with a minimum of 2.5 minutes in defrost.
If the coil temperature does not reach 32_F (0_C) within the interval, the interval timer will be reset and start over.
SUpon initial power up the first defrost interval is defaulted to 30 minutes. Remaining intervals are at selected times.
SDefrost is only allowed to occur below 50_F (10_C) outdoor ambient temperature.
The outdoor fan output (ODF) will remain off for 20 seconds after termination. This delay will allow time for the system to capture the heat from the outdoor coil and reduce the “steam cloud” effect that may occur on transition from defrost to the heating cycle. The outdoor fan output OFF delay of 20 seconds may be defeated to enable the fan to energize immediately at the time of termination and 12 seconds prior to the reversing valve de-energizing, through the User Interface setup screen available with SYSTXBBUID01-C UI, or forced defrost pins as follows: