Operation - Honeywell T8411R Manual

To set the °F/°C indication and heat cycle rate:
1. If the room temperature is displayed
in °F, set the temperature setpoint to
52°F. If the room temperature is dis-
played in °C, set the temperature
setpoint to 11°C.
2. Press the keys simultaneously
for more than two seconds to light all
segments on the display and to
enter installer setup mode. When
the keys are released, a two-digit
software code is displayed.
OPTIONAL SYSTEM CHECKOUT
When the heat or cool outputs are turned on, the five-minute
off-timer safety feature is bypassed.
When in steps 2. and 3. only, the
heat or cool outputs on and off. Change the SYSTEM switch
setting to test heat or cool outputs. No action takes place If the
system switch is in the Off position.
The following examples of system settings show a two digit
software code on the display. The code shown is only an
example; codes can vary.
System setting at Heat:
To turn heat on, press the
To turn auxiliary heat on, press the
To turn auxiliary heat off, press the
time.
To turn heat off, press the
System setting at Cool:
To turn cool on, press the
To turn cool off, press the
3. Press the key. Factory information is displayed. Infor-
mation displayed varies by model. This information is
only for factory use.
4. Press the key again to display °C or °F.
5. Press the key to change the °C or °F indi-
cation.
NOTE: Stage one heat and cool cycle rates are
fixed at 3 cph. Only stage two heat cycle
rates are selectable.
6. Press the key to display the heat cycle rate
of 3, 6, or 9. If the desired cycle is displayed,
press the key to exit the installer setup
M14683
M18426
key can be used to turn
key.
M18431
key.
M18432
key a third
M18433
key a fourth time.
M18434
key.
M18435
key.
M18434
M14688
M14689
M14690
T8411R ELECTRONIC HEAT PUMP THERMOSTAT
mode. To change the heat cycle rate, press the
scroll between 3, 6, and 9. Stop scrolling when the
desired rate is displayed.
7. Press the
ing algorithm configuration
default.
8. Press the
cooling algorithm to C1 or C3.
C1 = Standard cooling algorithm.
C3 = Aggressive cooling algorithm (can cause
overshooting).
9. Press the
(CC) is displayed. A typical example is
shown, but CC varies by model. This informa-
tion is for factory use only.
10. Press to save all changes, exit installer
setup mode and return to normal operation.
NOTE: After exiting installer setup mode, change the set-
point to the desired room temperature.

OPERATION

The T8411R Thermostat provides two-stage heat and one-
stage cool temperature control with proportional plus integral
control to eliminate droop.
Comfort Period
In mild weather, the heat pump cycles continuously to maintain the
Aux Ht
sensed temperature within 1°F of the setpoint. In moderate weather,
the heat pump cycles longer, minimizing the need for auxiliary
heat. The heat pump runs the majority of the time in severe
weather and only shuts off for brief periods using auxiliary
heat to maintain temperature within 1°F of setpoint.
Thermal Performance
During severe weather, the T8411R actually controls closer to
the setpoint than a conventional control. This is because the
heat anticipator is replaced by two electronic control
strategies— cycling by heat anticipation and proportional plus
integral (P+I) control.
Electronic cycling by heat anticipation acts like a traditional heat
anticipator except that it never needs adjusting for various con-trol
circuit load currents. It cycles off the heating system slightly before the
room temperature reaches the setpoint to keep heat that remains in the
ductwork from overheating the room.
In severe weather, a conventional control with a heat
anticipator tends to turn off the system too soon so the
effective setpoint is somewhat below the setpoint. In very cold
weather, the difference between setpoint and effective control
point can be 5°F or 6°F (2°C or 3°C) with a conventional
control. This phenomenon is called droop.
Proportional plus integral action eliminates droop by adjusting
the on time of the stage until the control point matches the
setpoint. The T8411R maintains the space temperature within
1°F of the setpoint.
This zero droop performance provides improved occupant
comfort and energy savings. Occupants do not need to
continually adjust thermostat settings to maintain desired
temperature, even during severe weather.
7
key to display cool-
key again to change
key again. Current configuration
key to
or
M18421
M18420
68-0185—2