Honeywell CHRONOTHERM IV DELUXE T8624D Product Data page 17

Operation Sequence
The thermostat energizes specific terminals depending what
the Fan and System are set to. The LCD will display the time,
room temperature, system and fan selection. Symbols will be
displayed when the heating, cooling or fan is energized. See
Table 10 for specific information.
NOTE: Not all the thermostat models have all the terminals
listed in the Energize column.
Table 10. Multistage System Sequence of Operation.
Selection
Fan System Call
Auto Off None
On Off None
Auto Cool None
Auto Cool or Stage 1
Auto Cooling
Auto Cool or Stage 2
Auto Cooling
Auto Heat None
Auto Heat or Stage 1
Auto heating
Auto Heat or Stage 2
Auto heating
Auto Auto None
a
G is energized and fan symbol is displayed on duel fuel
models when set for electric heat.
b
Based on last piece of equipment called (cooling = O or
heating = B) and Installer Setup selection.
Equipment Protection
As part of the operational sequence, the thermostat
microprocessor also incorporates minimum off time for all
heating and cooling stages. Using the minimum off time
assures that rapid cycling of equipment does not occur, which
extends equipment life. Minimum off times are set in the
Installer Setup.
Thermostat Operation
Startup
When power to the thermostat is turned on, a startup and
initialization program begins. The startup occurs only on initial
powerup. After total loss of power for an extended period, the
current time and day may need to be set, but the user
program is held. See Table 11 for the default values.
NOTE: Immediately following initialization, the user can
enter new setpoints to be used in place of the
default values.
T8624D CHRONOTHERM
Energize Display
None None
G
O None
O, G and Y1
and
O, G, Y1 and
Y2
and
B None
a
B, G and W1
and
a
B , G , W1
and W2
and
b None
O or B
®
IV DELUXE PROGRAMMABLE THERMOSTAT
Table 11. Default Time, Setpoint and Fan Settings.
Period Time
Wake 6:00 AM 70°F (21°C)
Leave 8:00 AM
Return 6:00 PM 70°F (21°C)
Sleep 10:00 PM
Adaptive Intelligent Recovery® Feature
Adaptive Intelligent Recovery® control assures that the
comfort setting is achieved at the programmed time
regardless of weather conditions. Conventional recovery,
however, starts recovery at the beginning of the programmed
time period and used the equipment to achieve the comfort
settings as soon as possible.
Adaptive Intelligent Recovery® control calculates the
recovery ramp based on the number of degrees away from
the desired setpoint, previous equipment performance, and
weather history to initiate recovery at the optimal time to
achieve the comfort setting at the desired time.
Once the recovery ramp is intersected, the setpoint changes
from the setback setpoint to the comfort setpoint. This change
snaps on both stages of the equipment and runs both stages
until the setpoint is reached. If the setpoint is reached too
early or too late, the ramp is adjusted for the next days'
recovery. See Fig. 13.
70°F
60°F
SLEEP
HEATING MODE
Fig. 13. Gradual temperature change in recovery.
17
Heat Cool
Setpoint Setpoint Setting
78°F Auto
(25.5°C)
62°F 85°F Auto
(16.5°C) (29.5°C)
78°F Auto
(25.5°C)
62°F 82°F Auto
(16.5°C) (28°C)
SETPOINT
TEMPERATURE
ACTUAL
TEMPERATURE
WAKE
M6185A
68-0166—1
Fan