Bryant 187B - Manual (Page 7)

7
UTILITY RELAY *
UTILITY SIGNAL
OPEN RELAY
* SUPPLIED BY UTILITY PROVIDER
MODEL
PLUG
LLS
Liquid Line Solenoid
MODEL
PLUG
A06526
Fig. 6 -- 2--Stage Control Board
Evolution Controlled Low Ambient Cooling
This unit is capable of low ambient cooling down to 0_F
(--17.78_C) 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 less than outdoor
air temperature (+3_F / 1.67_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 is more than outdoor
air temperature (+ 25_F / 13.89_C) or outdoor coil temp
is more than 80_F (26.67_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.
— The PWM output for both high and low--stage equals the
value for low--stage operation, below 55_F (12.8_C).
Check Charge
Models 180B / 187B should be charged in high stage compressor
operation. 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.
187B
/180B