Bryant Evolutiont Series s with Puronr Refrigerant 286A User Manual

Page 9

UTILITY RELAY

UTILITY SIGNAL

OPEN RELAY

SUPPLIED BY UTILITY PROVIDER

MODEL
PLUG

A06525

LLS

Liquid Line Solenoid

MODEL
PLUG

A06526

Fig. 6 -- 2--Stage Control Board

GENERAL INFORMATION
Low Ambient Cooling

When this unit is operating below 55_F (12.78_C) 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

(4.4 _C) OAT. Fan will cycle based on coil and outdoor air
temperature.
Evolution controlled low ambient mode operates as follows:

Fan is OFF when outdoor coil temp is < (outdoor air temperature

+ 3_F / 1.7_C) or outdoor fan has been ON for 30 minutes. (Fan

is turned off to allow refrigerant system to stabilize.)

Fan is ON when outdoor coil temp > (outdoor air temperature +

25_F / 13.9_C) or outdoor coil temp > 80_F/26.7_C or if

outdoor fan has been OFF for 30 minutes. (Fan is turned on to

allow refrigerant system to stabilize.)

Low 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 288A models, the PWM output for both high and low stage
equals the value for low stage operation below 55_F (12.8_C).

Defrost

This control offers 5 possible defrost interval times: 30, 60, 90, 120

minutes, or AUTO.
These are selected by dip switches on the unit control board or by

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:

When defrost time <3 minutes, the next defrost interval=120

minutes.

When defrost time 3--5 minutes, the next defrost interval=90

minutes.

When defrost time 5--7 minutes, the next defrost interval=60

minutes.

When 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 (0_C) for 4 minutes
during the interval.
The defrost cycle is terminated when the coil temperature reaches

65_F (18.33_C)or 10 minutes has passed.
On 286A models, defrost will occur in low-- or high--stage as

demanded by the thermostat or User Interface regardless of OAT
On 288A 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 288A 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.

Upon initial power up the first defrost interval is defaulted to

30 minutes. Remaining intervals are at selected times.

Defrost is only allowed to occur below 50_F (10_C)outdoor

ambient temperature.

286A

/288A