© 2002 Digital Security Controls Ltd.
1-800-387-3630 • www.dsc.com
Printed in Canada 29034522 R001
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Mode
Fan
Outdoor
Day/Night
HS-EMS400
Single-Compressor Heat Pump Thermostat
Operating Instructions
Introduction
The HS-EMS400 Digital Communicating Thermostat is designed to pro-
vide accurate control and display of room temperature. The thermostat nor-
mally displays room temperature, mode of operation (i.e. Day or Night),
and whether Cooling or Heating is currently on. The six buttons on the
front of the unit allow complete control of the thermostat. You may specify
different Heating and Cooling setpoints, and change them easily by pushing
a button. Temperature can be displayed in either °C or °F. The thermostat
also allows you to select either continuous fan operation, or fan operation
only during operation of the heating/cooling device(s).
Modes of Operation
Select the desired mode of operation by toggling the MODE button:
—indicates Cooling system only. “COOL” is displayed for 5 seconds.
—indicates Heating system only. “HEAT” is displayed for 5 seconds.
—indicates both the Heating and Cooling (automatic). “AUTO” is
displayed for 5 seconds).
(flashing)—indicates Cool is ON.
(flashing)—indicates Heat is ON.
Eht - indicates Emergency Heat
OFF—shuts off thermostat. Heating and Cooling systems will not operate.
Fan operation is still possible.
Caution:
Avoid using the OFF mode during cold weather to prevent dam-
age from freezing.
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Temperature Control
Cooling:
Select the temperature you want the thermostat to maintain while in Cool
mode, press the mode button until Cool mode is selected, then press the
or
buttons until the desired temperature is displayed. The cooling set-
point temperature is displayed for 5 seconds.
Heating:
Select the temperature you want the thermostat to maintain while in Heat
mode, press the mode button until Heat mode is selected, then press the
or
buttons until the desired temperature is displayed. The heating set-
point temperature is displayed for 5 seconds.
Auto:
The thermostat will automatically switch from heating to cooling as deter-
mined by the selected setpoints in heating and cooling.
NOTE: The thermostat will not allow less than 1 C (2 F) difference
between the heating and cooling setpoints.
Fan Control
The Fan will come on automatically when the system is operating, but there
is no indication of this on the display. To select continuous Fan operation,
press the FAN button and the display will show
. This is recommended
for electronic air cleaners and continuous ventilation requirements.
Outdoor (ODT) Button
When the outdoor temperature sensor option is connected to your thermo-
stat, you can display the current outdoor temperature by pressing the but-
ton. If this option is not connected, the thermostat will display _ _
with
no numbers.
Emergency Heat Indication
The center LED at the top of the thermostat lights when the system calls for
Emergency (Auxiliary) Heat.
Day/Night Button
The Day/Night button is used to select the Occupancy setting. When first
installed, the thermostat is set to Day occupancy setting and the display will
show the
symbol and the Day temperature. By pressing the Day/Night
button you can change to the Night occupancy setting and the display will
show the
symbol and the Night temperature. This button can be used to
toggle between Day and Night modes. Within each mode the temperature
can be modified. The thermostat will remember any new settings.
Celsius/Fahrenheit
Simultaneously press
and
to toggle between Celsius ( C) and Fahr-
enheit ( F) temperature display.
Optional Indoor/Outdoor Remote Sensors
The thermostat can accept indoor and outdoor remote temperature sensors
(EMS-ITS and EMS-OTS) for monitoring of temperatures where these
sensors are located.
Connecting indoor sensors disables the temperature sensor on the thermo-
stat thereby increasing the flexibility of where the thermostat can be
located. For temperature averaging over a large area, a minimum of two
indoor sensors are required.
Indoor and outdoor sensors are available separately. For more details about
installing these sensors, please refer to the Installation Instructions included
with the sensors.
Temperature Accuracy
Full accuracy is only achieved after the thermostat has been installed and
powered for at least one hour.
Power Failures
No battery is required to maintain the temperature setpoints in the case of a
power loss, regardless of duration.
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