Bryant instruction manual Check Charge, Defrost Hold, Forced Defrost, Quiet Shift, 286A / 288A

286A / 288A

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:

SThe ODF fan delay defeat can be toggled by shorting the forced defrost pins for >15 seconds while in the standby

mode (status LED on solid). The LED will start to flash when the toggle has taken place.

SStatus code 4 shows the fan delay defeat is active (no delay) S Status code 3 shows that it is not active (20 second delay)

The code will continue to be displayed until after the short is removed. Once the short is removed, there is a 5 second wait before the code is cancelled. The code that is flashing will finish before going back to sold LED. the control is shipped with the ODF fan delay defeat NOT active. the change in status is remembered until toggled to a new status. A power down / power up sequence will not reset the status. It may be necessary to do the toggle twice to cycle to the desired state of defeat.

Defrost Hold

In a non-communicating system, if the thermostat becomes satisfied (Y1 or Y1 and Y2) before the defrost cycle is terminated, the control will “hold” in defrost mode and finish the defrost cycle on the next call for heat.

On 286A and 288A models, with communicating Evolution Control, defrost hold is not needed in a communicating system because the User Interface will complete the defrost cycle before shutting down the system.

Forced Defrost

With non-communicating (non-Evolution) control, forced defrost can be initiated by manually shorting the 2-pin header labeled FORCED DEFROST (see Fig 6) on the control board for 5 seconds then releasing.

On 286A and 288A with communicating (Evolution) control, forced defrost is initiated with the User Interface.

On all models, during a Forced Defrost:

SIf coil temperature is at defrost temperature of 32_F (0_C), and outdoor air temperature is below 50_F (10_C), a full

defrost sequence will occur.

SIf coil temperature or outdoor air temperature does not meet the above requirements, an abbreviated 30 second defrost will occur.

Quiet Shift

Quiet Shift is a field-selectable defrost mode which may eliminate occasional noise that could be heard at the start of the defrost cycle and restarting of the heating cycle. With a non-communicating system, this feature must be enabled by selecting the 3rd position of the 3-position dip switch. For 286A and 288A models with communicating (Evolution) systems, it must be enabled at the User Interface. When activated, the following sequence of operation will occur. Reversing valve will energize and compressor will turn off for 30 seconds, then turn back on to complete defrost. At the end of the defrost cycle, the reversing valve de-energizes, compressor will turn off for another 30 seconds, and the fan will turn off for 40 seconds, before starting in the heating mode.

Liquid-Line Solenoid Accessory

In heat pump long-line applications, a liquid-line solenoid is required to control refrigerant migration in the heating mode. The solenoid should be installed near the outdoor unit with the arrow facing the outdoor unit. This is the direction of flow control. See application manual for long-line application details.

Accessory Liquid Solenoid with Evolution Communicating Control: When using the Evolution Control, the liquid-line solenoid output is provided at the Y1 connection. Connect the solenoid as shown in the wiring label diagram. This is a 24vac output that is energized whenever the compressor is energized. It closes, in the compressor off mode, to prevent refrigerant migration into the unit through the liquid-line.

On Models with Accessory Liquid Solenoid Using a Non-Communicating Thermostat: The liquid solenoid is connect to the Y1 and C terminal connections. The liquid solenoid closes, in the compressor off mode, to prevent refrigerant migration into the unit through the liquid-line.

Check Charge

All 286A units must be charged in high stage only.

Factory charge amount and desired subcooling are shown on unit rating plate. Charging method is shown on information plate inside unit. To properly check or adjust charge, conditions must be favorable for subcooling charging. Favorable conditions exist when the outdoor temperature is between 70_F and 100_F (21.11_C and 37.78_C), and the indoor temperature is between 70_F and 80_F (21.11_C and 26.67_C). Follow the procedure below:

Unit is factory charged for 15ft (4.57 m) of lineset. Adjust charge by adding or removing 0.6 oz/ft of 3/8 liquid line above or below 15ft (4.57 m) respectively.

For standard refrigerant line lengths (80 ft/24.38 m or less), allow system to operate in cooling mode at least 15 minutes. If conditions are favorable, check system charge by subcooling method. If any adjustment is necessary, adjust charge slowly and allow system to operate for 15 minutes to stabilize before declaring a properly charged system.

If the indoor temperature is above 80_F (26.67_C), and the outdoor temperature is in the favorable range, adjust system charge by weight based on line length and allow the indoor temperature to drop to 80_F (26.67_C) before attempting to check system charge by subcooling method as described above.

If the indoor temperature is below 70_F (21.11_C), or the outdoor temperature is not in the favorable range, adjust charge for line set length above or below 15ft (4.57 m) only. Charge level should then be appropriate for the system to achieve rated capacity. The charge level could then be checked at another time when the both indoor and outdoor temperatures are in a more favorable range.

NOTE: If line length is beyond 80 ft (24.38 m) or greater than 20 ft (6.10 m) vertical separation, See Long Line Guideline for special charging requirements.

Heating Check Chart Procedure

To check system operation during heating cycle, refer to the Heat Pump Charging Instructions label on outdoor unit. This chart indicates whether a correct relationship exists between system operating pressure and air temperature entering indoor and outdoor units. If pressure and temperature do not match on chart, system refrigerant charge may not be correct. Do not use chart to adjust refrigerant charge.

NOTE: In heating mode, check refrigerant charge only when pressures are stable. If in doubt, remove charge and weigh in correct refrigerant charge.

NOTE: When charging is necessary during heating season, charge must be weighed in accordance with unit rating plate, ±0.6 oz./ft. of 3/8-in. liquid-line above or below 15 ft., respectively.

EXAMPLE:

To calculate additional charge required for a 25-ft. line set:

25 ft. - 15 ft. = 10 ft. X 0.6 oz./ft. = 6 oz. of additional charge.

10