69-1591–1
4
ELECTRONIC HEAT PUMP THERMOSTAT
Pub. No. 11-HD28D2-1
Using Thermostat Keys
Use thermostat keys to:
• Set temperature,
• Display present setting,
• Configure Installer Setup,
• Check System-Test,
• Display outdoor temperature (select models).
• Set system operation,
• Set fan operation.
See Fig. 6 for the key information.
Fig. 7. ASYSTAT 575 (automatic changeover)
System and Fan key locations.
NOTE: Always press the system and fan keys with your
fingertip or similar blunt tool. Sharp instruments
like a pen or pencil point can damage the
keyboard.
Emergency Heat
The Emergency Heat feature allows you to turn on the
electric heat section of the system by moving the
System switch to the Em. Ht. position. The LED lights
(see Fig. 7) when the thermostat is moved to the
Em. Ht. position or when the system goes into defrost.
The thermosat displays Em. Ht. when the system calls
for emergency heat.
LED indication
One LED indicator is located on the lower right bottom
of the thermostat. It indicates when a CHECK signal is
sent to the thermostat from the system. See Fig. 7.
Temperature Settings
The default setpoint for heat is 70°F (21°C) and for cool is
78°F (25.5°C). Press the increase ▲ or decrease ▼ key to
change the present setting. To change between heat and
cool, press the Information i key until the setting to be
changed appears.
Cooling Droop
Cooling system operation or cycling below the setpoint
temperature is called “Cooling Droop”. Thermostats that
provide this operation improve the comfort during
extended off periods by providing air circulation to
prevent stagnation and improved moisture removal due
to increased run time. Cooling Droop is most effective in
mild weather conditions and during nighttime operation
(low load). The effect of Cooling Droop on indoor
temperature operation typically lowers the indoor
temperature by up to one or two degrees. If the cooling
droop is not desired, it can be disabled.
Comfort R™
Comfort R helps achieve comfort with a lower humidity
level. When enabled (selected in installer setup) the
thermostat calculates a fan delay on a call for cool. The
calculated delay maximizes dehumidification and
comfort from the air conditioning system.
M10147C
i
Press to select
heating or cooling
equipment.
Em. Ht.
-Emergency heating
Heat— Heating equipment
Off — No equipment
Cool—Cooling equipment
Auto—Thermostat
automatically selects
heating and cooling
equipment.
Press to select
heating or cooling
equipment.
On— Fan runs continuously
Auto—Fan runs when
heating or cooling
equipment operates
System
System
System
Fan
Fan
Fan
TWO LED INDICATORS ON MOST MODELS.
1
1
M680
TEMPERATURE
SETTING
Fig. 6. Thermostat key locations and descriptions.
SETTINGS
System and Fan Settings
System settings control the thermostat operation as
follows:
Em. Heat: The thermostat cycles the Emergency Heat
relay and the highest heat stage. The cooling
system is off. The compressor is de-energized.
Heat: The thermostat controls the heating.
Off: Both the heating and cooling are off.
Cool: The thermostat controls the cooling.
Auto: The thermostat automatically changes between
heating and cooling operation, depending on the
indoor temperature.
Fan settings control the system fan as follows:
On: Fan operates continuously.
Auto: Equipment controls fan.
The system default setting is Heat and the fan default
setting is Auto. Use the keyboard to change to the desired
settings. See Fig. 7.