Mars 70801 Installation And Operating Instructions Manual

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Model 70801

INSTALLATION AND OPERATING INSTRUCTIONS

Non-Programmable Electronic
Thermostat Heat/Cool

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Compatible with low voltage single stage gas, oil or electric heating or cooling systems and single stage
heat pumps. For use on 24VAC systems (not to exceed 30VAC) and 250mv to 750mv millivolt heating
only systems.

WARNING!

• To prevent electrical shock and/or equipment damage, disconnect electric power to system at main
fuse or circuit breaker box until installation is complete.

• Do not use this thermostat on applications with voltages above 30VAC.

• Wiring must conform to all local and national building/electrical codes and ordinances.

• Do not short (jumper) across terminals on the gas valve or at the system control to test the installation.
This will damage the thermostat and void the warranty.

• This thermostat is equipped with automatic compressor protection to prevent damage due to short
cycling. The short cycle protection provides a 5-minute delay between heating (heat pump models) or
cooling cycles to prevent the compressor from being damaged.

• Do not switch the system to cool if the outdoor temperature is below 50 F (10 C). This may damage
the cooling system and may cause personal injury.

• This thermostat should be used only as described in this manual.

SPECIFICATIONS

Electrical Rating: 24 Volt AC (18-30 VAC)

1 Amp Maximum per Terminal

2 Amps Total Load
Control: 1 Heat / 1Cool Non-Heat Pump
Set Point Range: 45 F – 90 F (7.0 C – 32.0 C)
Accuracy: +/- 1 F (.5 C)
Terminations: RC, RH, C, G, Y, W, B, O
Power: 24VAC

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Removing The Existing Thermostat

1) CAUTION: Make certain the power to the system has been disconnected.

2) Remove the cover of the old thermostat and locate the wires that are connected to the terminal board.

IMPORTANT: Before removing these wires, NOTE (ON A PIECE OF PAPER) THE COLOR OF EACH WIRE
AND THE CORRESPONDING TERMINAL MARKING ON THE OLD THERMOSTAT.

3) Remove the wires from the terminals. Remove the old thermostat and mounting base from the wall.

Installing The New Thermostat

1) CAUTION: Make certain the power to the system has been disconnected.

2) If this is a new installation, locate the thermostat 4 to 5 feet above the floor in accordance with applicable

codes. Select a location that provides good airflow. Avoid locations in direct sunlight, near sources of heat,
or near air vents. NOTE: The display is designed to be best viewed from a front downward angle.

3) Remove the back plate of the thermostat by gently depressing the bottom locking tab and swinging the back

plate up and away.

4) Place the back plate against the wall in the desired mounting location with the thermostat wires protruding

from the wall through the large rectangular whole in the back plate.

5) Mark placement of the (2) mounting holes (oval shaped holes in back plate) on the wall, remove the back

plate, and drill (2) 3/16” holes.

6) Tap supplied plastic anchors into the holes.

7) Secure the back plate to the wall with the supplied screws making certain the thermostat wires have been

inserted through the large rectangular hole in the back plate.

8) Carefully attach the thermostat wires to the appropriate connections on the terminal board on the back plate.

Use the notes taken from step 2 of Removing The Existing Thermostat to determine their location on the new
thermostat. Reference wiring diagrams are available in the back of this manual.

9) Carefully place the thermostat body face down on a soft surface to expose the main circuit board. Gently set

the following switches in the correct position for the application.

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• GAS / ELECTRIC: Configures the thermostat to either gas/oil or electric heating systems.

• C / F: Sets the display in either Celsius or Fahrenheit.

• NORM / HP: Configures the thermostat for normal heating/cooling systems or heat pump systems (single

stage).

10) Attach the thermostat body to the back plate by resting the top of the thermostat body on the two clips on

the upper portion of the back plate. Then gently press the front body into place until the bottom locking
tab snaps into place. NOTE: The terminal board pins must be properly aligned with the sockets on the
terminal board (on the back plate) in order for the front body to properly snap into place.

11) Set the system switch to the OFF position.

12) Set the fan switch to the AUTO position.

13) Remove the clear plastic film from the display.

Testing The New Thermostat

WARNING!

• Do not switch the system to cool if the outdoor temperature is below 50 F (10 C). This may damage the

cooling system and may cause personal injury.

• This thermostat is equipped with automatic compressor protection to prevent damage due to short cycling.

The short cycle protection provides a 5-minute delay between heating (heat pump models) or cooling
cycles to prevent the compressor from being damaged.

1) Restore the system power. The LCD (liquid crystal display) will dis-

play the room temperature. The LCD will illuminate at the touch of
the red or blue arrow keys. LCD will return to its normal state after
10 seconds.

2) Set the fan switch to the ON position. The system blower should start.

3) Set the fan switch to the AUTO position. The system blower should stop.

4) Set the system switch to the HEAT position and depress the red arrow key until the temperature set point

is at least 3 degrees above the room temperature. The LCD will display a flame icon to indicate heat.
The heating system should start within several seconds (the system blower may not come on immediate­ly).

Image shows
room temperature of 78.

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