Bryant LEGACY 580J - Manual (Page 49)

49
SEQUENCE OF OPERATION (cont.)
On the initial power to the EconoMi$er IV control, it will
take the damper up to 2--1/2 minutes before it begins to
position itself. After the initial power--up, further changes
in damper position can take up to 30 seconds to initiate.
Damper movement from full closed to full open (or vice
versa) will take between 1--1/2 and 2--1/2 minutes. If free
cooling can be used as determined from the appropriate
changeover command (switch, dry bulb, enthalpy curve,
differential dry bulb, or differential enthalpy), then the
control will modulate the dampers open to maintain the
mixed--air temperature setpoint at 50_F (10_C) to 55_F
(13_C). If there is a further demand for cooling (cooling
second stage -- Y2 is energized), then the control will
bring on compressor stage 1 to maintain the mixed--air
temperature setpoint. The EconoMi$er IV damper will be
open at maximum position. EconoMi$er IV operation is
limited to a single compressor.
Heating —
The sequence of operation for the heating is the same as
an electromechanical unit with no economizer. The only
difference is how the economizer acts. The economizer
will stay at the Economizer Minimum Position while the
evaporator fan is operating. The outdoor--air damper is
closed when the indoor fan is not operating.
Refer to Service and Maintenance Manual for further
details.
Optional Perfect Humidityt Dehumidification System
Units with the factory equipped Perfect Humidity option
are capable of providing multiple modes of improved
dehumidification as a variation of the normal cooling
cycle.
The Perfect Humidity option includes additional valves in
the liquid line and discharge line of each refrigerant
circuit, a small reheat condenser coil downstream of the
evaporator, and Motormaster variable--speed control of
some or all outdoor fans. Operation of the revised
refrigerant circuit for each mode is described below.
NOTE: x = refrigerant circuit A, B, or C.
Normal Cooling
Refrigerant flows from the outdoor condenser through the
normally open Cooling Valve (CV.x) to the expansion
device. Reheat1 Valve (RH1.x) and Reheat2 Valve
(RH2.x) are closed.
Reheat1 (Subcooling Mode) -- 580J17--28
This mode increases latent cooling and decreases sensible
cooling compared to normal cooling. Refrigerant flows
from the outdoor condenser, through the normally open
Reheat1 Valve (RH1.x), and through the reheat condenser
coil to the expansion device. Cooling Valve (CV.x) and
Reheat2 Valve (RH2.x) are closed.
Reheat2 (Hot Gas Reheat Mode) -- 580J17--28
This mode provides maximum latent cooling with little to
no sensible capacity. This mode can operate to provide
dehumidification when there is no cooling demand. Like
Reheat1 mode, refrigerant flows from the outdoor
condenser, through the normally open Reheat1 Valve
(RH1.x), and through the reheat condenser coil to the
expansion device. The Cooling Valve (CV.x) is closed.
Reheat2 Valve (RH2.x) is open which provides some
compressor discharge gas to the reheat condenser to
further increase the reheat of the evaporator airstream.
COMP
COND COIL PERFECT HUMIDITY COIL
EVAP COIL
INDOOR ENTERING
AIR
OUTDOOR AIR
METERING
DEVICE
CLOSED VALVE
OPEN VALVE
RH1.x
RH2.x
CV.x
a48-8172
C11151
Normal Cooling Mode -- Perfect Humidity System (580J17--28)
580J