CONTENTS
Installation Instructions for
Heating & Air Conditioning
1F78H
Non-Programmable Thermostat
Y OUR THERMOST A T REPLACES
Typical System Compatibility Chart 1F78H
Standard Heat Only 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 Systems No
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 No
12 VDC Mobile Home Application No
Multistage Systems No
Systems Exceeding 30VAC, 1.5 Amp No
* Requires common wire for 24VAC at the thermostat
Preparations.................................................. 1
Thermostat Details ........................................ 1
Removing Old Thermostat ............................ 1
Mounting and Wiring ..................................... 2
Check Thermostat Operation ........................ 3
Configuration Menu....................................... 4
Specifications ................................................ 5
Troubleshooting ............................................ 5
PREPARATIONS
1
Assemble tools required as shown below.
HAND OR POWER
DRILL WITH 3/16 INCH
DRILL BIT, IF NEEDED
FLAT BLADE SCREWDRIVER
SPIRIT LEVEL OR PLUMB BOB AND LINE OPTIONAL—
THERMOSTAT DOES NOT NEED TO BE LEVEL TO WORK PROPERLY
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
W905
Clip for
Hydronic
System
W904
W905
W904
Clip for
Celsius Display
Figure 1. Thermostat base
W
RH
GC
GAS
ELEC
Electric/Gas
Switch
Mounting
hole
BRC
Y
O
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
EMERSON ELECTRIC CO.
9797 REAVIS ROAD
ST. LOUIS, MISSOURI 63123-5398
www.white-rodgers.com
PART NO. 37-6450A
Printed in U.S.A.
0247
REMOVING OLD THERMOSTAT
3
CONTINUED FROM FIRST PAGE
ATTENTION! This product does not contain mercury. How-
ever, 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 2892 Harrison Street,
Batesville, AR 72501-2117 for proper disposal.
MOUNTING AND WIRING
4
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.
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
C
* Factory installed jumper wire between the RH
and RC terminals must remain in place.
Other Manufacturers’
Terminal Designation
4
RH
R
R
G
G
W
W
Y
Y
C
C
*
M
R
V
-
F
G
H
W
C
Y
X
C
Attach Thermostat Base to Wall
1. Remove the packing material from the thermostat. Gently pull
the cover 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. Place a level against bottom of base, 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.
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 by changing the first option in
the configuration menu to SL (see configuration menu, page 5).
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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
OBC
NOTE
For Heat only,
attach to RH and W
Figure 2. Typical wiring diagram for
heat only, 4-wire, single transformer systems
Figure 3. Typical wiring diagram for
cool only, 4-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.
OBC
Figure 4. Typical wiring diagram for
heat/cool, 5-wire, single transformer systems
Heating
System
Heating
System
RCOBC
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
OBC
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, 6-wire, two-transformer systems
G W
Fan
JUMPER
WIRE
RCOBC
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
RCOBC
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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CHECK THERMOST A T OPERA TION
5
CONTINUED FROM THIRD PAGE
Before you begin using your thermostat, you should be familiar
with its features and with the display and the location and
operation of the thermostat buttons. Your thermostat consists of
two parts: the thermostat cover and the base. To remove the
cover, gently pull it straight out from the base. To replace the
cover, line up the cover with the base and press gently until the
cover snaps onto the base.
The Thermostat Buttons and Switches
1
(Up arrow) Raises temperature setting.
(Down arrow) Lowers temperature setting.
2
3
FAN switch (ON, AUTO).
SYSTEM switch (COOL, OFF, HEAT).
4
The Display
5
is displayed when the SYSTEM switch is in the HEAT
position. is displayed (non-flashing) when the SYSTEM
switch is in the COOL position.
when the compressor is in lockout mode.
6
Displays current temperature.
is displayed (flashing)
WHITE-RODGERS
FAN SYSTEM
OFFON AUTO COOL HEAT
3
5
Figure 8. Thermostat display, buttons, and switches
4
76
1
2
7
Displays currently set temperature (this is blank when
SYSTEM switch is in the OFF position).
Operating Features
Now that you are familiar with the thermostat buttons and display,
read the following information to learn about the many features of
the thermostat.
• SIMULTANEOUS HEATING/COOLING SETPOINT
STORAGE — You can enter both your heating and cooling
setpoints at the same time. There is no need to re-enter the
thermostat at the beginning of each season.
• TEMPERATURE SETTING — Press or until the
display shows the temperature you want. The thermostat will
keep the room temperature at the selected temperature.
• °F/°C CONVERTIBILITY — The factory default setting is
Fahrenheit. If you need Celsius temperature setting, go to
menu mode and change the fifth option to C (see configuration menu, page 5).
• TEMPERATURE DISPLAY ADJUSTMENT — Your new
thermostat has been accurately set in our factory. However,if
you wish, you may adjust your new thermostat temperature
display to match your old thermostat. This can be accomplished (within a ±4° range) by going into the menu mode (see
configuration menu, page 5).
CONFIGURATION MENU
6
The configuration menu allows you to set certain thermostat operating characteristics to your system or personal requirements.
With the system switch in “OFF” mode, press and keys
at the same time to enter the configuration menu. The display will
show the first item in the configuration menu.
The configuration menu table summarizes the configuration
options. An explanation of each option follows.
Press and together momentarily to change to the next
menu item. To exit the menu, change the system switch from OFF
to HEAT or COOL. If no action is taken within fifteen minutes, the
thermostat will revert to normal operation.
2) Select FA or SL (Fast or Slow) Heating Cycle Rate—The
FA setting is frequently used for gas, oil or electric heat. The
SL setting produces a longer heating cycle which is normally
for hot water or steam (hydronic) systems. Both settings
produce very accurate temperature control and can be set to
your personal preference. FA cycles the system just under
1°F and the SL setting cycles at approximately 1.5F°.
3) Not Available
4) Select Compressor Lockout LOC OFF or ON—Selecting
LOC ON will cause the thermostat to wait 5 minutes before
turning on the compressor if the heating and cooling system
loses power. It will also wait 5 minutes minimum between
cooling cycles. This is intended to help protect the compressor from short cycling. Some newer compressors already
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Configuration Menu
Step
Press Button(s)
1
Set system switch
2
3
4
5
6
7
switch from OFF
to HEAT or COOL
* Press
to OFF
and
and
and
and
and
Move system
and simultaneously to advance to next item
Displayed (Factory Default)
(FA)
d-L (ON)
LOC (OFF)
0 HI (0)
(F)
Press or to select:
have a time delay built in and do not require this feature. Your
compressor manufacturer can tell you if the feature is already
present in their system. When the compressor time delay
occurs it will flash the
for about five minutes then turn on
the compressor.
5) Select Temperature Display Adjustment 4 LO to 4 HI—
Allows you to adjust the room temperature display 4° higher
or lower. Your thermostat was accurately calibrated at the
factory but you have the option to change the display temperature to match your previous thermostat.
6) Select F° or C° Readout—Changes the display readout to
Centigrade or Fahrenheit as required.
Comments
SL
OFF
ON
4 LO to 4 HI
C
SPECIFICATIONS
7
System switch must be OFF to configure thermostat
Select FA or SL (Fast or Slow) heating cycle rate
N/A
Select compressor lockout OFF or ON
Select temperature display adjustment higher or lower
Select temperature display to F or C
Returns to normal operation
ELECTRICAL DATA
Electrical Rating:
20 to 30 VAC 50/60 Hz.
0.05 to 1.2 Amps (Load per terminal)
1.5 Amps Maximum Total Load (All terminals combined)
THERMAL DATA
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 Temperature Range: -40°F to 150°F
TROUBLESHOOTING
8
Symptom Possible Cause Corrective Action
No Heat/No Cool/No Fan 1. Blown fuse or tripped circuit breaker. Replace fuse or reset breaker.
(common problems) 2. Furnace power switch to OFF. Turn switch to ON.
3. Furnace blower compartment door or Replace door panel in proper position to engage
panel loose or not properly installed. safety interlock or door switch.
No Heat 1. Pilot light not lit. Re-light pilot.
2. System Switch not set to Heat. Set System Switch to Heat and raise temperature
above room temperature.
3. Loose connection to thermostat or system. Verify thermostat and system wires are securely
attached.
4. Furnace Lock-Out Condition. Heat may also Many furnaces have safety devices that shut down
be intermittent. when a lock-out condition occurs. If the heat works
intermittently contact the furnace manufacturer or
local service person for assistance.
5. Heating system requires service or Diagonistic: Set System Switch to Heat and raise
thermostat requires replacement. 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 on, 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 .
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TROUBLESHOOTING
8
Symptom Possible Cause Corrective Action
No Cool 1. System Switch not set to Cool. Set System Switch to Cool and lower temp below
room temp.
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 for No Heat
thermostat requires replacement. 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. Check each wire connection to verify they are not
2. Possible short in thermostat. shorted or touching together. No bare wire should
3. Possible short in heat/cool/fan system. stick out from under terminal screws. If the
4. Fan Switch set to Fan On. 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 1. The location of the thermostat and/or the Digital thermostats normally provide precise
(narrow or wide temperature swing) size of the Heating System may be temperature control and may cycle faster than
influencing the cycle rate. 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, go to menu mode 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 changing cycle time from FAST to
SLOW on the menu mode contact a local
service person for additional suggestions.
Cooling Cycles Too Fast or Too Slow 1. The location of the thermostat and the size The cycle rate for cooling is fixed and can not be
(narrow or wide temperature swing) of the Cooling System can influence the adjusted. Contact a local service person for
cycle rate. suggestions.
Thermostat Setting and Thermostat 1. Thermostat thermometer setting requires The thermometer can be adjusted +/- 4 degrees.
Thermometer Disagree adjustment. See Temperature Display Adjustment in the
Operation section.
Blank Display and/or Keypad 1. Thermostat loss of power Check possible blown fuse or tripped breaker.
Not Responding 2. Voltage spike or static discharge. Turn the system power off. W ait for 5 minutes and
turn the power on.
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