Mars 70801 Operating instructions

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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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•
•
•
10)
11)
12)
13)
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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).
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.
Set the system switch to the OFF position.
Set the fan switch to the AUTO position.
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 disImage shows
room temperature of 78.
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).
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5) Set the system switch to the OFF position. The system should
shut down within several seconds. The LCD will again display
only the room temperature.
6) Set the system switch to the COOL position and depress the
blue arrow key until the temperature set point is at least 3
degrees below the room temperature. The LCD will display a
snowflake icon to indicate A/C. The cooling system should start
within several seconds. WARNING: Do not perform this test if
the outdoor temperature is below 50 F.
Image shows room temperature
of 70 and HEAT set point of 73.
Image shows room temperature
of 78 and A/C set point of 68.
7) Set the system switch to the OFF position. The system should shut down within several seconds. The LCD
will again display only the room temperature.
Programming The User Settings
Temperature Differential is factory set at .5 F (0.25 C) for both heating and cooling cycles. The room temperature must change .5 F (0.25 C) from the set point temperature before the thermostat will initiate a call for heat
or A/C. This should be appropriate for most applications. However, if the system is cycling on and off too
frequently, the setting can be adjusted as follows.
1) With the system setting in the OFF position, simultaneously
depress the red and blue arrow keys. The LCD (liquid crystal
display) will display the temperature differential setting. Using
the red and blue arrow keys set the differential to the desired
setting of .5, 1, or 2. The higher the setting, the less frequently the system will cycle.
Image shows temperature
differential setting of 0.5.
2) When the desired setting is made, release the key and the unit will automatically store the setting after 5 seconds.
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Operating The New Thermostat
1) Set the System switch to either the HEAT or COOL position and the Fan switch to either the AUTO or ON
position. NOTE: In AUTO, the system blower will run only when the A/C or heat is running. In ON, the
system blower will operate continuously.
2) Use the red and blue arrow keys to select the desired temperature set point.
3) The LCD (liquid crystal display) displays the room temperature on
the left and the set point temperature on the right. Note: The set
point temperature may sometimes differ slightly from the room
temperature due to a rapidly changing room temperature or a differential setting of 1 or 2.
Image shows room temperature
of 78 and A/C set point of 68.
Understanding Additional Features
•
High Temperature Protection: While in the HEAT position, if the room temperature reaches 93 F (34 C),
the thermostat will automatically shut off. In the unlikely event the room temperature reaches 99 F (37 c),
a mechanical bimetal switch will shut off the thermostat.
•
Low Temperature Protection: While in the HEAT position, if the room temperature drops below 40 F (4
C), the thermostat will automatically initiate a call for heat.
•
Compressor Protection: To protect the system compressor(s) from damage, the thermostat features a 5
minute delay. After the cooling system (or heat pump turns off), the thermostat will not allow it to re-start
until the 5 minute delay expires. A blinking snowflake indicates this feature has been activated. Once the
5 minute delay expires, the snowflake will illuminate continuously and the system will be able to re-start
when called upon.
NOTE: For the purpose of unit installation, this delay can be overridden by
depressing the RESET button. This will erase any programmed settings.
•
System Reset: The thermostat can be reset to factory software settings. All user entered settings will be
lost. The reset will also override the 5 minute compressor protection feature. To reset the thermostat, gently press the reset button on the front panel using a paper clip or similar small pointed object.
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Troubleshooting
SYMPTOM
CORRECTIVE ACTION
Display is blank
Check thermostat wiring & connections.
Check circuit breaker/fuse panel.
No heat
Set system switch to HEAT and raise set point above room temperature.
Check thermostat wiring and connections.
Check pilot light or HSI system on furnace.
No cool
Set system switch to COOL and lower set point below room temperature
If snowflake is blinking, allow the 5 minute compressor lock-out to expire.
Check thermostat wiring & connections.
System turns on/off
too frequently or
not enough
Adjust the differential setting on the thermostat.
A high differential decreases cycle rate and a low differential increases
cycle rate.
Display is not illuminated
Room temperature and
set point disagree
Touch the up or down arrow key. Display will illuminate for 10 seconds.
Normal (depending on differential setting).
Check for drafts that could quickly change the room temperature
before the system is able to correct it.
System fan runs continuously
Set fan switch to AUTO.
Check thermostat wiring & connections.
HI is displayed
Reduce room temperature or allow a newly installed thermostat to
acclimate. HI indicates a room temperature reading greater than
90 F (32 C).
LO is displayed
Increase room temperature or allow a newly installed thermostat to
acclimate. LO indicates a room temperature reading less than 45 F (7 C).
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Wiring Diagrams
Install Jumper
RC
RH
Typical 4-Wire System
C
G
Y
FAN
CONTROL
W
HEAT
CONTROL
COOL
CONTROL
HOT
24 VAC
TRANSFORMER COM
8
B
O
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Wiring Diagrams
Typical 5-Wire System
RC
RH
C
HOT
G
Y
FAN
CONTROL
COOL
CONTROL
COOL 24 VAC
TRANSFORMER
W
HOT
COM
9
B
O
HEAT
CONTROL
HEAT 24 VAC
TRANSFORMER
COM
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Wiring Diagrams
Typical 2-Wire Millivolt System
RC
RH
C
G
W
Y
B
O
HEAT
CONTROL
HOT
24 VAC
TRANSFORMER
COM
Typical Single Stage Heat Pump System
RC
RH
Install Jumper
C
G
W
Y
FAN
CONTROL
B
Install Jumper
COMPRESSOR
CONTROL
HOT
24 VAC
TRANSFORMER
10
O
REV. VALVE
COOL ENERGIZED
REV. VALVE
HEAT ENERGIZED
COM
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Warranty
ONE YEAR LIMITED WARRANTY
Motors & Armatures Inc. warrants each new MARS thermostat against any defects due to
non-conforming material or workmanship for a period of one year after the original date of
purchase by a professional service technician and does not include the cost of removal or
re-installation. This warranty extends to the contractor or dealer who purchased the
product from a wholesaler. For warranty claims, consumers should contact the contractor
or dealer who installed the thermostat.
This warranty and Motors & Armatures’ liability does not include damage to merchandise or
thermostat resulting from accident, alteration, neglect, misuse, improper installation, or any
other failure to follow Motors & Armatures’ installation and operating instructions. Contact
Motors & Armatures Inc. for full details on product warranty policy.
Motors & Armatures Inc.
250 Rabro Drive East
Hauppauge, NY 11788
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INSTALLATION AND OPERATING INSTRUCTIONS
Non-Programmable Electronic Thermostat Heat/Cool
Model
70801
®