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Installation Instructions for

Heating & Air Conditioning

1F78

Non-Programmable Thermostat

CONTENTS

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

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

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

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

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

Specifications ................................................ 5

Troubleshooting ............................................ 5

PREPARATIONS

THERMOSTAT DETAILS

REMOVING OLD THERMOSTAT

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 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.

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.

CAUTION

!

PART NO. 37-6615A

0435

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

Assemble tools required as shown below.

YOUR THERMOSTAT  REPLACES

1

2

3

WIRE CUTTER/STRIPPER

W

RH

B

RC

G

O

Y

+

-

+

-

GAS

ELEC

W904

W905

Figure 1. Thermostat base

Mounting

hole

Mounting

hole

W905

Clip for 

Hydronic  

System

W904

Clip for 

Celsius Display

Electric/Gas 

Switch

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

FLAT BLADE SCREWDRIVER

White-Rodgers is a division 

of Emerson Electric Co.

www.white-rodgers.com

Typical System Compatibility Chart

1F78

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

 

Summary of Contents for 1E78-151

Page 1: ...ng the following procedures 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 CAUTION PART NO 37 6615A 0435 Failure to follow and read all instructions carefully before installing or operating this control could cause personal injury and or property damage Assemble tools required as shown...

Page 2: ...w the thermostattoenergizethefanimmediatelyonacallforheat Ifyou 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 w...

Page 3: ...alve is energized when the system switch is in the HEAT position Fan Relay NOTE To prevent static discharge problems touch side of ther mostat 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 pow...

Page 4: ...he factory default setting is Fahrenheit Clipping W904 jumper on the circuit board see fig 1 will alter this feature to Celsius temperature setting LOW BATTERY INDICATOR If the 2 AAA alkaline batteries are low and should be replaced the display will be blank except for LO BATTERY When the batteries are low pressing any button will cause the display to operate for ten seconds After ten seconds the ...

Page 5: ...mostat clicks contact the furnace manufac turer or a service person to verify the heating is operating correctly No Cool 1 SYSTEM Switch not set to Cool Set SYSTEM Switch to COOL and lower setpoint temperature below room temperature 2 Loose connection to thermostat or system Verify thermostat and system wires are securely attached 3 Cooling system requires service or Same procedure as diagnostic f...

Page 6: ... 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 1 The location of the thermos...

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