Honeywell PC8900A Manual page 35

Adaptive Intelligent Recovery™ Operation
Adaptive Intelligent Recovery™ operation is Honeywell's
trademark for the way the Comfort Center™ system controls
the heating and cooling equipment during recovery from an
energy savings setting (SLEEP, LEAVE) to a comfort setting
(WAKE, RETURN). This provides additional energy savings.
The advantages are:
• Comfort setting is achieved at the programmed time and
maintained regardless of the weather conditions;
occupants come home and wake up in comfort.
• Drafts from low temperature discharge air are minimized
during occupied periods.
• Comfort Center™ control system automatically uses the
more economical first stage of the heat pump as the
primary heat source during the heat mode recovery,
avoiding the use of the expensive second-stage of heating
(auxiliary heat).
• Comfort and energy savings can be achieved in both
heating and cooling.
• Reduces heat pump and air conditioner compressor
cycling, extending equipment life.
Adaptive Intelligent Recovery™ operation is used during
recovery from energy savings. It is bypassed when configured
for conventional recovery but not when setpoint is temporarily
changed. When Adaptive Intelligent Recovery™ operation is
bypassed, the system operates the stages of equipment like a
conventional control.
PC8900A Used with W8900A,C Remote Module
(Conventional Heat/Cool Applications)
During recovery, the Comfort Center™ program calculates the
amount of time required to bring the living space from the
current room temperature (achieved in the energy savings
mode) to the comfort temperature programmed for the comfort
mode. When that time is reached, the present setpoint
changes from the energy savings setpoint to the comfort
setpoint. The result is that the living space temperature is at
the programmed setpoint at the programmed time, providing
the occupants with the maximum comfort. See Fig. 33.
PC8900A Used with W8900B Remote Module
(Heat Pump Applications)
During recovery, the Comfort Center™ program works to
achieve comfort in the same manner, by calculating the
amount of time required to bring the living space from the
current room temperature to the comfort temperature
programmed for the comfort mode. The living space
temperature reaches the programmed setpoint at the
programmed time so the occupants achieve maximum
comfort.
Another way the Comfort Center™ program minimizes
auxiliary heat usage is by having two recovery ramps: one for
stage-one compressor and one for auxiliary heat.
Fig. 33. Heat pump Adaptive Intelligent Recovery™ ramp.
Operation
Seasonal weather changes allow the Adaptive Intelligent
Recovery™ ramp to change on a daily basis and still meet the
comfort needs of the occupants. In the fall, heating loads are
light so recovery begins very late in the energy savings period.
As fall changes to winter, loads increase and the Adaptive
Intelligent Recovery™ ramp shifts so recovery begins earlier
each day. Conversely, recovery begins later each day as
heating loads decrease from winter to spring. See Fig. 34 and
35.
70 F
60 F
SLEEP
Fig. 34. Fall to winter Adaptive
Intelligent Recovery™ ramp.
70 F
60 F
SLEEP
Fig. 35. Winter to spring Adaptive
Intelligent Recovery™ ramp.
Energy Savings Period
In mild to moderate weather, the PC8900A calls on the heat
pump only when the sensed temperature falls below the
setpoint. Under mild to moderate conditions, the more
costly auxiliary heat is not needed. In severe weather, the heat
pump cycles only when the sensed temperature falls below
setpoint and auxiliary heat cycles continuously. See Fig. 36
through 38.
35
COMPRESSOR SETPOINT
AUXILIARY HEAT SETPOINT
ROOM TEMPERATURE
WAKE
M6406A
SETPOINT
TEMPERATURE
ACTUAL
TEMPERATURE
WAKE
M6185A
SETPOINT
TEMPERATURE
ACTUAL
TEMPERATURE
WAKE
M6186
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