Mars 70802 User manual

INSTALLATION AND OPERATING INSTRUCTIONS
Non-Programmable Electronic
Thermostat 2 Heat/1 Cool
Heat Pump
®
Model 70802
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WARNING!
• To prevent electrical shock and/or equipment damage, disconnect electric power to system at main fuse or cir-
cuit breaker box until installation is complete.
• This thermostat is for use on 24 VAC multi-stage heat pump systems.
• Do not use this thermostat on single stage systems or 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 cool-
ing 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
3 Amps Total Load
Control: 2 Heat / 1 Cool Heat Pump
Set Point Range: 45 F – 90 F (7.0 C – 32.0 C)
Accuracy: +/- 1 F (.5 C)
Terminations: R, C, G, Y1,W2, E, 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
Note: This thermostat is for use exclusively on 24 VAC multi-stage heat pump systems with two stages of heat-
ing and one stage of cooling.
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.
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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. A reference wiring diagram is 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 C / F switch to the desired setting (Celsius or Fahrenheit).
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.
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.
•Do not jumper across terminals at the heating or cooling system control board to test the thermostat. This
may damage the unit 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.
1) Restore the system power. The LCD (liquid crystal display) will display 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 sec-
onds.
Image shows
room temperature of 78.
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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).
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) After 5 minutes (to allow the compressor short cycle protection
delay to expire) from completing step 5, 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 tem-
perature. The LCD will display a snowflake icon to indicate A/C. The cooling system should start within sev-
eral seconds. WARNING: Do not perform this test if the outdoor temperature is below 50 F.
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 the first stage 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. The second stage heating differential is permanently set at 2 F (1 C) and cannot be adjust-
ed. This should be appropriate for most applications. However, if the system is cycling on and off too frequently,
the first stage setting can be adjusted as follows.
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.
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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 degrees. The higher the setting, the less
frequently the system will cycle.
2) When the desired setting is made, release the key and the unit will automatically store the setting after 5
seconds.
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 tempera-
ture 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.
4) The second stage heat will automatically be initiated when the thermostat is in the HEAT position and the
room temperature is less than the differential set point of the first and second stages combined. Note:
Setting the thermostat to EMER (emergency heat) setting will force the thermostat to operate both stages
simultaneously during normal heat operation. WARNING: This mode will override the compressor short
cycle protection feature. To help protect the compressor from
being damaged, set the temperature differential to 2 in order
to minimize system cycling.
Image shows temperature
differential setting of 0.5.
Image shows room temperature
of 78 and A/C set point of 68.
Image shows room temperature
of 78 and heat set point of 73.
Image shows room temperature
of 70 and heat set point of 73
with second stage heat (AUX)
initiated.
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Understanding Additional Features
• High Temperature Protection: While in the HEAT setting, 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 setting, 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 or flame icon indicates this feature has been activat-
ed. 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, gen-
tly press the reset button on the front panel using a paper clip or similar small pointed object.
•Emergency Heat: The EMER switch will force the thermostat to operate using both heating stages simulta-
neously during normal heat operation. WARNING: The compressor short cycle protection feature is dis-
abled in this mode! If this setting is selected, set the temperature differential to 2 in order to minimize sys-
tem cycling.
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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.
Blinking snowflake/flame Allow the 5 minute compressor lock-out to expire.
System turns on/offAdjust the differential setting on the thermostat.
too frequently or A high differential decreases cycle rate and a low differential increases cycle
not enough rate.
Display is not illuminated Touch the up or down arrow key. Display will illuminate for 10 seconds.
Room temperature and Normal (depending on differential setting).
set point disagree Check for drafts that could quickly change the room temperature before the
system is able to correct it.
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(Troubleshooting cont.)
SYMPTOM CORRECTIVE ACTION
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
RCGY1 W2 EBO
REV. VALVE
COOL ENERGIZED
24 VAC
TRANSFORMER
COM
HOT
FAN
COMPRESSOR
AUX HEAT
(STAGE 2)
EMERGENCY
HEAT
REV. VALVE
HEAT ENERGIZED
Typical Multi-Stage System
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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 2 Heat/1 Cool Heat Pump
®
Model 70802
70802-IM 12/14/06 3:11 PM Page 12