White Rodgers EMERSON 1E78 User Manual

CONTENTS

Installation Instructions for

Heating & Air Conditioning

1E78

5/2 Day Programmable Thermostat

Y OUR THERMOST AT REPLACES

Typical System Compatibility Chart 1E78

Standard Heat Only Two Wire Gas or Oil Fired Systems (24 volt) Yes
Electronic Ignition Heat Only Two Wire Systems (24 volt) Yes
Electronic Ignition Heat Only Gas or Oil Fired Systems (24 volt) Yes
Standard Heat/Cool Systems (24 volt) Yes
Heat/Cool Systems Electric Heat (24 volt) Yes
Heat Only Electric Heat Systems (24 volt) Yes
Cool Only Systems (24 volt) Yes
Heat Pump Systems (No Aux or Emergency Heat) Yes
Hot Water Zone Heat Only (Two Wire) Systems Yes
Hot Water Zone Heat Only (Three Wire) Systems No
Line Voltage Heating or Baseboard 110/240 Volt Systems No
Millivolt Systems Floor or Wall Furnaces Yes
12 VDC Mobile Home Application Yes
Multistage Systems No
Systems Exceding 30VAC, 1.5 Amp No

Preparations.................................................. 1

Thermostat Details ........................................ 1

Removing Old Thermostat ............................ 1

Mounting and Wiring ..................................... 2

Check Thermostat Operation........................ 3

Programming your Thermostat ..................... 4

Specifications ................................................ 6

Troubleshooting ............................................ 6

PREPARATIONS

1

Assemble tools required as shown below.

FLAT BLADE SCREWDRIVER

HAND OR POWER
DRILL WITH 3/16 INCH
DRILL BIT, IF NEEDED

WIRE CUTTER/STRIPPER

Failure to follow and read all instructions carefully
before installing or operating this control could cause
personal injury and/or property damage

THERMOSTAT DETAILS

2

Mounting

Hole

RC

GRH

W

YOB

Base

Mounting

Hole

W903 - clip to disable EMR feature
W904 - clip for Celcius display
W905 - clip for hydronic system

Figure 1. Thermostat

ELEC GAS

Back of

Thermostat Body

W905
W904
W903

Elec/Gas

Switch

REMOVING OLD THERMOSTAT

3

CAUTION

!

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

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:
a. The cover, which may be either a snap-on or hinge type.
b. The base, which is removed by loosening all captive screws.
c. 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.

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.

White-Rodgers is a division

of Emerson Electric Co.

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PART NO. 37-6542B

Replaces 37-6542A

0434

REMOVING OLD THERMOSTAT

3

CONTINUED FROM FIRST PAGE

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 and return to White-Rodgers at 2895 Harrison Street,
Batesville, AR, 72501 for proper disposal.

MOUNTING AND WIRING

4

CAUTION

!

Take care when securing and routing wires so they do
not short to adjacent terminals or rear of thermostat.
Personal injury and/or property damage may occur.

TERMINAL CROSS REFERENCE CHART

New Thermostat

Terminal Designation

RH
RC

G

W

Y

Other Manufacturers’
Terminal Designation

4

RH

M

R

R

V

G

G

F

W

W

H

Y

Y

C

**

R5

R

-

-

G

G

4

W

Y6

Y

WARNING

!

Do not use on circuits exceeding specified voltage.
Higher voltage will damage control and could cause
shock or fire hazard.

Do not short out terminals on gas valve or primary
control to test. Short or incorrect wiring will damage
thermostat and could cause personal injury and/or
property damage.

Thermostat installation and all components of the sys­tem shall conform to Class II circuits per the NEC code.

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 GAS/ELECTRIC switch (see
fig. 1) and switch it to the ELECTRIC 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.

* These are four-wire, single-transformer systems.
Factory installed jumper wire between the RH
and RC terminals must remain in place.

Energy Management Recovery (EMR)

This thermostat is set to operate with EMR. This causes the
thermostat to start the heating or cooling system early to have
the room temperature reach the program setpoint at the time
the period is to start.

To disable EMR, clip jumper W903 (see Fig. 1).

Attach Thermostat Base to Wall

1. Remove the packing material from the thermostat. Gently pull
the thermostat 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 SYS-
TEMS, 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 “LO BATTERY” appears on the display, the batteries are low
and should be replaced with fresh “AAA” Energizer® alkaline
batteries. The batteries are located on the back of the thermostat
body (see fig. 1).

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MOUNTING AND WIRING

4

CONTINUED FROM SECOND PAGE

Y

Y

Cooling
System

NOTE

Y

Cooling
System

G W

Fan

Relay

G W

Fan

Relay

G W

Fan

Relay

OB

NOTE

For 2-wire Heat only,
attach to RH and W

Figure 2. Typical wiring diagram for

heat only, 3-wire, single transformer systems

Figure 3. Typical wiring diagram for

cool only, 3-wire, single transformer systems

RED jumper wire (provided with thermostat) must be

connected between thermostat RH and RC terminals
for proper thermostat operation with this system.

OB

Figure 4. Typical wiring diagram for

heat/cool, 4-wire, single transformer systems

Heating
System

Heating
System

RCOB

RC

JUMPER

WIRE

24 VAC

JUMPER

WIRE

RH

24 VAC

TRANSFORMER

THERMOSTAT

RH

TRANSFORMER

JUMPER

WIRE

RH

RC

24 VAC

TRANSFORMER

THERMOSTAT

SYSTEM

120 VAC

SYSTEM

Hot

120 VAC

Neutral

THERMOSTAT

SYSTEM

Hot

120 VAC

Neutral

Hot

Neutral

OB

Y

Cooling
System

G W

Fan

Relay

Heating
System

THERMOSTAT

RH

RC

SYSTEM

24 VAC

HEATING

TRANSFORMER

24 VAC

COOLING TRANSFORMER

Hot

120 VAC

Neutral

Hot

120 VAC

Neutral

Figure 5. Typical wiring diagram for

heat/cool, 5-wire, two-transformer systems

G W

Fan

JUMPER

WIRE

RCOB

24 VAC

THERMOSTAT

RH

SYSTEM

TRANSFORMER

Hot

120 VAC

Neutral

JUMPER

WIRE

Y

Reversing

Compressor

Valve*

Contactor

* Reversing valve is energized when the
system switch is in the COOL position

Relay

Figure 6. Typical wiring diagram for heat pump

with reversing valve energized in COOL

G W

Fan

JUMPER

WIRE

RCOB

24 VAC

THERMOSTAT

RH

SYSTEM

TRANSFORMER

Hot

120 VAC

Neutral

JUMPER

WIRE

Y

Reversing

* Reversing valve is energized when the
system switch is in the HEAT position

Valve*

Compressor

Contactor

Relay

Figure 7. Typical wiring diagram for heat pump

with reversing valve energized in HEAT

CHECK THERMOST A T OPERA TION

5

NOTE

To prevent static discharge problems, touch side of ther­mostat to release static build-up before touching any keys.

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

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.

Cooling System

CAUTION

!

To prevent compressor and/or property damage, if the
outdoor temperature is below 50°F, DO NOT operate the
cooling system.

This thermostat has a time delay between cooling cycles to allow
the head 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

to adjust thermostat setting below room tempera­ture. The blower should come on immediately on high speed,
followed by cold air circulation

3. Press 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 to adjust thermostat setting above room tempera­ture. The heating system should begin to operate.

3. Press to adjust temperature setting below room tem­perature. The heating system should stop operating.

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