SUBBASE
(MODEL 300
ONLY)
BASE
COVER
ANTICIPATOR
CAPTIVE SCREWS
MOUNTING SCREWS
Figure 1.
Installation Instructions for
Heating only
1C20
and
Heating & Cooling
1C26
WHITE-RODGERS
CONTENTS
Preparations........................................... 1
Thermostat Features.............................. 2
Removing Old Thermostat ..................... 3
Mounting and Wiring .............................. 4
Set Heat Anticipator ............................... 5
New Thermostat Operation .................... 6
Specifications ......................................... 7
Troubleshooting ..................................... 8
PREPARATIONS
THERMOSTAT FEATURES
REMOVING OLD THERMOSTAT
Before removing wires from old thermostat’s switching subbase,
label each wire with the terminal designation it was removed from.
Some models also include an adaptor plate to cover unpainted
surfaces. Thermostat wires pass through the adaptor plate center
opening.
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.
Make a note here of the anticipator setting on
the old thermostat for future reference and use in step 5.
The heat anticipator pointer, if adjustable, will be set at one of a
series of numbers representing the current rating of the primary
control in your furnace. The number will be one of the following:
.2, .4, .8, etc. or 0.2, 0.4, 0.8, etc.
If no heat anticipator/indication is showing, do not be concerned;
move on to the next step.
Printed in U.S.A.
PART NO. 37-6335A
0142
WHITE-RODGERS
EMERSON ELECTRIC CO.
9797 REAVIS ROAD
ST. LOUIS, MISSOURI 63123-5398
www.white-rodgers.com
Failure to follow and read all instructions carefully be-
fore installing or operating this control could cause
personal injury and/or property damage
Assemble tools required as shown below.
YOUR THERMOSTAT REPLACES
Adaptor Plate
(optional)
Description
1C20 1C26
Standard Heating & Cooling Systems - 4 or 5 wires No Yes
Standard Heat Only Systems Yes Yes
Millivolt Heat Only Systems - Floor or Wall Furnaces Yes Yes
Standard Central Air Conditioning No Yes
Gas or Oil Heat Yes Yes
Electric Furnace Yes Yes
Hydronic (Hot Water) Zone Heat - 2 Wires Yes Yes
Hydronic (Hot Water) Zone Heat - 3 Wires No No
Heat Pump (No Aux or Emergency Heat) No Yes
Heat Pump (with Aux or Emergency Heat) No No
Baseboard Electric Heating or Line Voltage (120 or 240 Volt) No No
1
2
3
WIRE CUTTER/STRIPPER
SPIRIT LEVEL OR PLUMB BOB AND LINE OPTIONAL—
THERMOSTAT MUST BE LEVEL TO WORK PROPERLY
HAND OR POWER
DRILL WITH 3/16 INCH
DRILL BIT, IF NEEDED
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
!
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