White Rodgers Thermostat 1E78 -140 Installation Instructions Manual

White Rodgers Thermostat 1E78 -140 Installation Instructions Manual

Installation Instructions for Heating & Air Conditioning 1E78 Non-Programmable Thermostat

White Rodgers Thermostat 1E78 -140 Table of CONTENTS

Thermostat Details..............................1
Removing Old Thermostat..................1
Mounting and Wiring...........................2
Check Thermostat Operation..............3


Typical System Compatibility Chart


Standard Heat Only Two Wire Gas or Oil Fired Systems (24 volt)


Electronic Ignition Heat Only Two Wire Systems (24 volt)


Electronic Ignition Heat Only Gas or Oil Fired Systems (24 volt)


Standard Heat/Cool Systems (24 volt)


Heat/Cool Systems Electric Heat (24 volt)


Heat Only Electric Heat Systems (24 volt)


Cool Only Systems (24 volt)


Heat Pump Systems (No Aux. or Emergency Heat)


Hot Water Zone Heat Only (Two Wire) Systems


Hot Water Zone Heat Only (Three Wire) Systems


Line Voltage Heating or Baseboard 110/240 Volt Systems


Millivolt Systems Floor or Wall Furnaces


VDC Mobile Home Application


Multistage Systems


Systems Exceeding 30VAC, 1.5 Amp







White Rodgers THERMOSTAT 1E78 -140 DETAILS

white rodgers THERMOSTAT 1E78 -140 DETAILS

NOTE: Earlier models refer to 37-7006 for jumper locations.


Before removing wires from old thermostat’s switching subbase, label each wire with the terminal designation it was removed from.

  1. Remove Old Thermostat: A standard heat/cool thermostat consists of three basic parts:
    • The cover, which may be either a snap-on or hinge type.
    • The base, which is removed by loosening all captive screws.
    • The switching subbase, which is removed by unscrewing the mounting screws that hold it on the wall or adaptor plate.
  2. Shut off electricity at the main fuse box until installation is complete. Ensure that electrical power is disconnected.
  3. Remove the front cover of the old thermostat. With wires still attached, remove wall plate from the wall. If the old thermostat has a wall mounting plate, remove the thermostat and the wall mounting plate as an assembly.
  4. Identify each wire attached to the old thermostat using the labels enclosed with the new thermostat.
  5. Disconnect the wires from the old thermostat one at a time. DO NOT LET WIRES FALL BACK INTO THE WALL.
  6. Install new thermostat using the following procedures.

ATTENTION! This product does not contain mercury. However, this product may replace a unit which contains mercury. Do not open mercury cells. If a cell becomes damaged, do not touch any spilled mercury. Wearing non-absorbent gloves, take up the spilled mercury and place into a container which can be sealed. If a cell becomes damaged, the unit should be discarded.

Mercury must not be discarded in household trash. When the unit this product is replacing is to be discarded, place in a suitable container. Refer to www.white-rodgers.com for location to send product containing mercury. 


Electric Heat or Single-Stage Heat Pump Systems

This thermostat is configured from the factory to operate a heat/cool, fossil fuel (gas, oil, etc.), forced air system. It is configured correctly for any system that DOES NOT require the thermostat to energize the fan on a call for heat. If your system is an electric or heat-pump system that REQUIRES the thermostat to turn on the fan on a call for heat, locate the ELEC/GAS switch (see fig. 1) and switch it to the ELEC position. This will allow the thermostat to energize the fan immediately on a call for heat. If you are unsure if the heating/ cooling system requires the thermostat to control the fan, contact a qualified heating and air conditioning service person.

Hydronic (Hot Water or Steam) Heating Systems

This thermostat is set to operate properly with a forced-air heating system. If you have a hydronic heating system (a system that heats with hot water or steam), you must set the thermostat to operate properly with your system.
The factory default setting is forced air heat. Clipping jumper W905 on the circuit board will produce a longer heating cycle which is normally for hot water or steam (hydronic) systems. Both settings produce a very accurate temperature control and can be set to your personal preference. As received, the thermostat cycles the system just under 1˚F. With W905 clipped, the system cycles at approximately 1.5˚F.


Attach Thermostat Base to Wall

  1. Remove the packing material from the thermostat. Gently pull the body straight off the base. Forcing or prying on the thermostat will cause damage to the unit. If necessary, move the electric heat switch (see ELECTRIC HEAT SYSTEMS, above).
  2. Connect wires beneath terminal screws on base using appropriate wiring schematic (see figs. 2 through 7).
  3. Place base over hole in wall and mark mounting hole locations on wall using base as a template.
  4. Move base out of the way. Drill mounting holes.
  5. Fasten base loosely to wall, as shown in fig. 1, using two mounting screws. Adjust until level, and then tighten screws. (Leveling is for appearance only and will not affect thermostat operation.) If you are using existing mounting holes, or if holes drilled are too large and do not allow you to tighten base snugly, use plastic screw anchors to secure subbase.
  6. Push excess wire into wall and plug hole with a fire-resistant material (such as fiberglass insulation) to prevent drafts from affecting thermostat operation.

Battery Location

This thermostat requires 2 “AAA” alkaline batteries to operate. If Battery indicator appears on the display, the batteries are low and should be replaced with fresh premium brand “AAA” alkaline batteries such as Duracell® or Energizer®. The batteries are located on the back of the thermostat body (see fig. 1).




If at any time during testing your system does not operate properly, contact a qualified service person.

Fan Operation
If your system does not have a G terminal connection, skip to Heating System.

  1. Turn on power to the system.
  2. Move FAN switch to ON position. The blower should begin to operate.
  3. Move FAN switch to AUTO position. The blower should stop immediately.

This thermostat has a time delay between cooling cycles to allow the vhead pressure in the compressor to stabilize. If the temperature is adjusted to call for cool within 5 minutes of the last cycle the snowflake icon will blink indicating the thermostat is locked out. After 3 to 5 minutes, the compressor will start and the snowflake icon will stop flashing. This helps prevent the compressor from cycling too quickly and is normal operation for the thermostat.

  1. Move SYSTEM switch to COOL position.
  2. Press DOWN to adjust thermostat setting below room temperature. The blower should come on immediately on high speed, followed by cold air circulation
  3. Press UP to adjust temperature setting above room temperature.

The cooling system should stop operating.

Heating System

  1. Move SYSTEM switch to HEAT position. If the heating system has a standing pilot, be sure to light it.
  2. Press UP to adjust thermostat setting above room temperature. The heating system should begin to operate.
  3. Press DOWN to adjust temperature setting below room temperature. The heating system should stop operating. 

White Rodgers 1E78 -140 Spesifications


Electrical Rating:
0 to 30 VAC 50/60 Hz. or D.C.
0.05 to 1.0 Amps (Load per terminal)
1.5 Amps Maximum Total Load (All terminals combined)


Setpoint Temperature Range:
45°F to 90°F (7°C to 32°C)
Operating Ambient Temperature Range:
32°F to 105°F
Operating Humidity Range:
0 to 90% RH (non-condensing)
Shipping Temperat 

White Rodgers 1E78 -140 TROUBLESHOOTING

Reset Operation
If a voltage spike or static discharge blanks out the display or causes erratic thermostat operation you can reset the thermostat by pressing UP and DOWN button at the same time while moving the SYSTEM switch from OFF to HEAT. This also resets the factory defaults. If the thermostat has power, has been reset and still does not function correctly contact your heating/cooling service person or place of purchase.

For optimum performance, we recommend replacing batteries once a year with fresh premium brand “AAA” alkaline batteries.



Possible Cause

Corrective Action

No Heat/No Cool/No Fan (common problems)

  1. Blown fuse or tripped circuit breaker.
  2. Furnace power switch to OFF.
  3. Furnace blower compartment door orpanel loose or not properly installed.

Replace fuse or reset breaker.

Turn switch to ON.

Replace door panel in proper position to engage safety interlock or door switch.

No Heat

  1. Pilot light not lit.
  2. SYSTEM Switch not set to HEAT.
  3. Loose connection to thermostat or system.
  4. Furnace Lock-Out Condition. Heat may also be intermittent.
  5. Heating system requires service or thermostat requires replacement.

Re-light pilot.

Set SYSTEM Switch to HEAT and raise setpoint temperature above room temperature.

Verify thermostat and system wires are securely attached.

Many furnaces have safety devices that shut   down when a lock-out condition occurs. If the  heat works intermittently contact the furnace  manufacturer or local service person for  assistance.

Diagnostic: Set SYSTEM Switch to HEAT and raise the setpoint above room temperature. Within a few seconds the thermostat should make a soft click sound. This sound usually indicates the thermostat is operating properly. If the thermostat does not click, try the reset operation listed above. If the  thermostat does not click after being reset contact  your heating and cooling service person or place  of purchase for a replacement. If the thermostat   clicks, contact the furnace manufacturer or a service person to verify the heating is operating   correctly.

No Cool

  1. SYSTEM Switch not set to COOL.
  2. Loose connection to thermostat or system.
  3. Cooling system requires service or thermostat requires replacement.

Set SYSTEM Switch to COOL and lower  setpoint  temperature below room temperature.

Verify thermostat and system wires are securely  attached.

Same procedure as diagnostic for No Heat     condition except set the thermostat to COOL and   lower the setpoint below the room temperature.   There may be up to a five minute delay before the  thermostat clicks in Cooling.

Heat, Cool or Fan Runs Constantly.

  1. Possible short in wiring.
  2. Possible short in thermostat.
  3. Possible short in heat/cool/fan system.
  4. FAN Switch set to Fan ON.

Check each wire connection to  verify they are not shorted or touching together. No bare wire should stick out from under terminal screws. Try resetting the thermostat as described above. If the condition  persists the manufacturer of your system or service person can instruct you on how to test the Heat/Cool system for correct operation. If the system operates correctly, replace the thermostat.

Furnace Cycles Too Fast or Too Slow (narrow or wide temperature swing)

1. The location of the thermostat and/or the size of the Heating System may be  influencing the cycle rate.

Digital thermostats normally provide precise  temperature control and may cycle faster than some older mechanical models. A faster cycle rate means  the unit turns on and off more frequently but runs for a shorter time so there is no increase in energy use. If you would like to increase the cycle time, clip Jumper W-905 as mentioned in the instructions for Hydronic Heating Systems. It is not possible to shorten the cycle time. If an acceptable cycle rate is not achieved as received or by clipping W-905 contact a local service person for additional suggestions.

Cooling Cycles Too Fast or Too Slow  (narrow or wide temperature swing)

1. The location of the thermostat and the size of the Cooling System can influence the cycle rate.

The cycle rate for cooling is fixed and can not be adjusted. Contact a local service person for suggestions.  

Thermostat Setting and Thermostat  Thermometer Disagree

1. Thermostat thermometer setting requires adjustment. 

The thermometer can be adjusted +/- 3 degrees. See Temperature Display Adjustment in the Operation section.

Blank Display and/or Keypad Not Responding

  1. Voltage spike or static discharge.
  2. Battery change required.

Replace batteries and check heat/cool system for proper operation. If a voltage spike occurs use  the Reset Operation listed above.

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Title : White Rodgers Thermostat 1E78 -140 Installation Instructions Manual
Format : PDF
Pages : 8 Pages
Language : English
File Size : 1 MB
White Rodgers Thermostat 1E78 -140 Manual

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