White Rodgers 1C26 Thermostat User Manual

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CONTENTS

Preparations ...........................................

Thermostat Features ..............................

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

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

Set Heat Anticipator ...............................

New Thermostat Operation ....................

Specifications .........................................

Installation Instructions for

Heating only

1C20

and

Heating & Cooling

Troubleshooting ..................................... 8

1C26

PREPARATIONS

YOUR THERMOSTAT REPLACES

Assemble tools required as shown below.

Description

1C20

1C26

Yes

Standard Heating & Cooling Systems - 4 or 5 wires

Standard Heat Only Systems

Yes

Millivolt Heat Only Systems - Floor or Wall Furnaces

Standard Central Air Conditioning

Gas or Oil Heat

FLAT BLADE SCREWDRIVER

WIRE CUTTER/STRIPPER

Yes

HAND OR POWER

DRILL WITH 3/16 INCH

DRILL BIT, IF NEEDED

Electric Furnace

Hydronic (Hot Water) Zone Heat - 2 Wires

Hydronic (Hot Water) Zone Heat - 3 Wires

Heat Pump (No Aux or Emergency Heat)

Heat Pump (with Aux or Emergency Heat)

Baseboard Electric Heating or Line Voltage (120 or 240 Volt)

SPIRIT LEVEL OR PLUMB BOB AND LINE OPTIONAL—

THERMOSTAT MUST BE LEVEL TO WORK PROPERLY

Yes

Failure to follow and read all instructions carefully be-

fore installing or operating this control could cause

personal injury and/or property damage

THERMOSTAT FEATURES

REMOVING OLDTHERMOSTAT

CAUTION

MOUNTING SCREWS

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.

ANTICIPATOR

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.

CAPTIVE SCREWS

SUBBASE

(MODEL 1C26

ONLY)

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

themountingscrewsthatholditonthewalloradaptorplate.

BASE

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.

COVER

Adaptor Plate

(optional)

If no heat anticipator/indication is showing, do not be concerned;

move on to the next step.

Figure 1.

PART NO. 37-6335B

Replaces 37-6335A

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0835

REMOVING OLDTHERMOSTAT

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.

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.

TERMINAL CROSS REFERENCE CHART

New Thermostat

Other Manufacturers’

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

the product containing mercury.

Terminal Designation

MOUNTING AND WIRING

* These are four-wire, single-transformer systems.

Factory installed jumper wire between the RH

and RC terminals must remain in place.

WARNING

Do not use on circuits exceeding specified voltage.

Higher voltage will damage control and could cause

shock or fire hazard.

it to the A terminal. This will allow the thermostat to energize

the fan immediately on a call for heat. If you are unsure if the

heating system requires the thermostat to control the fan,

contactaqualifiedheatingandairconditioningserviceperson.

For single stage heat pump applications (no auxillary heat),

install a short jumper wire (not included) across terminals

W and Y. If the system has a reversing valve connection

energized in Cooling, attach it to O. If the system has a

reversing valve connection energized in Heating, attach it to B

(see Fig. 4). This thermostat will not provide multi-stage

heating or cooling.

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 sys-

tem shall conform to Class II circuits per the NEC code.

1C20 (Heat Only Two Wire):

A. Mount base and adaptor plate: Mount base and adaptor

plate (optional) to wall using screws provided (see Fig. 1).

B. Attach wires: Attach one wire to R and the other wire to W on

base.

D. Mount Thermostat Base: Gently push excess wire back into

the wall opening and plug hole with a fire-resistant material,

such as fiberglass insulation to prevent drafts from affecting

thermostat operation. Mount the thermostat base to the sub-

base using the three captive screws on the thermostat base.

(See Fig. 1) Tighten the screws securely. Remove paper tag

from plastic contact cover. Proceed to Step #5.

C. Skip to Step #5.

1C26 (Heating and Cooling):

A. Remove base from subbase: Loosen the three screws on

the base and remove.

B. Mount switching subbase/adaptor plate: Use the screws

provided to mount the subbase and adaptor plate (optional) to

wall (see Fig. 1).

Factory-Installed Jumper

Heat

Relay

Compressor

Relay

Fan

Relay

Hot

C. Attach wires to appropriate terminals:

24 VAC

120 VAC

Neutral

• Fortwowiresystems(HeatOnlyorCoolOnly). Ifyouhave

a two-wire Heat Only system, attach one wire to RH and one

towireW.Ifyouhaveatwo-wire CoolOnlysystem,attachone

wire to RC and one to wire to Y. Leave the factory installed

jumper between RC and RH attached. Tighten any unused

terminals securely.

TRANSFORMER

Figure 2. Typical wiring for single transformer

heating/cooling system

• If your system has more than two wires: Use the cross

reference chart to determine correct wire connections. If you

have a four-wire heat/cool system leave the factory installed

jumper between RC and RH attached (see Fig 2.). If your

system has five wires remove the factory installed jumper

between RC and RH (see Fig 3.).

TRANSFORMER

Hot

TRANSFORMER

Hot

Heat

Relay

Compressor

Relay

Fan

Relay

24 VAC

120 VAC

Neutral

120 VAC

Neutral

Figure 3. Typical wiring for two-transformer

heating/cooling system

• Electric heat or single stage heat pump systems: This

thermostat is configured from the factory to operate a heat/

cool, fossilfuel(gas, oil, etc.)forcedairsystem. Itisconfigured

correctly for any system that DOES NOT require the thermo-

stat to energize the fan on a call for heat. If your system is an

electric heat or heat-pump system that REQUIRES the ther-

mostat to turn on the fan on a call for heat, remove the yellow

factory-installed jumper wire from the Y terminal and connect

Factory-Installed Jumper

Field-Installed Jumper

TRANSFORMER

Hot

Fan

Relay

Compressor

Relay

* *

24 VAC

120 VAC

Neutral

Terminal energized

in cooling

Terminal energized

in heating

* *

Figure 4. Typical wiring for single transformer,

single stage heat pump system

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SET HEAT ANTICIPATOR

Set anticipator to match the setting of your old thermostat you

noted in Step 3, or, the anticipator should be set to match the

current rating stamped on your main heating control. The heat

anticipator is adjustable from 0.15 to 1.2 amps. Adjust the antici-

pator by rotating the contact arm (see fig. 5). The anticipator

setting is indicated by the numbers on the base that the pointer

points to. If you are unsure where to set the anticipator contact the

heater manufacturer for a recommended setting.

Rotate contact arm

to adjust heat anticipator

NOTE

For Milivolt Application:

Rotate contact arm

to rest on this rivet.

Movethepointer counterclockwise to lengthen heatingsystem

cycles; move clockwise to shorten heating cycles. Adjustments

should not be greater than 1/2 marking at a time.

Arrow points to the

current rating of

the primary coontrol

Snap on Cover: Carefully align the cover with the base and snap

the cover onto the base.

Figure 5. Anticipator adjustment

Typical Zone Valve

Typical Gas Valve

Typical Oil Primary

24VAC

50/60 Hz

.43 Amps

24VAC

50/60 Hz

.35 Amps

50/60 Hz

.23 Amps

NEW THERMOSTAT OPERATION

1C20 Heat Only – After power is turned on, slide temperature

lever to desired setting. To turn heat off, slide lever all the way to

the left until it clicks.

Shows switch position

FAN

SYSTEM

OPERATION

AUTO ON

COOL OFF HEAT

No heating; no cooling; no fan

1C26 – This thermostat is easy to operate. Fig. 6 shows how the

heating/cooling system and fan operate when the switches are in

various positions. After power is turned on, use the system switch

to select either heating or cooling, or to turn the heating/cooling

system off. Use the fan switch to control fan operation. When the

fan switch is in the AUTO position, the fan will cycle with the

heating or cooling system (the fan will not run if the system switch

is in the OFF position and the fan switch is in the AUTO position).

When the fan switch is in the ON position, the fan will run

continuously, regardless of system switch position (even if the

system switch is set to OFF, the fan will run if the fan switch is in

the ON position).

No heating; no cooling; fan runs continuously

Cooling system cycles from thermostat; fan runs

continuously

Cooling system and fan cycle from thermostat

Heating system cycles from thermostat; fan cycles

from fan control on furnace

Heating system cycles from thermostat; fan runs

continuously

Figure 6. Subbase switching and thermostat/system

operation (1C26 only)

SPECIFICATIONS

ELECTRICAL DATA

THERMAL DATA:

Temperature Range ..............50°F to 90°F (10°C to 32°C)

Operating Humidity Range ... 0 – 90% noncondensing

Switch Rating ........................ 24 VAC (30 VAC max.)

Heating.................................... 0.15 to 1.2 Amps

Cooling .................................... 0 to 1.5 Amps

Switch Action ........................ Snap Action

Anticipator Rating:

Heating.................................... Adjustable from 0.15 to 1.2 Amps

Cooling .................................... Fixed

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TROUBLESHOOTING

Symptom

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.

Replace fuse or reset breaker.

Turn switch to ON.

3. Furnace blower compartment door or

panel loose or not properly installed.

Replace door panel in proper position to engage

safety interlock or door switch.

No Heat

1. Pilot light not lit.

Re-light pilot.

2. Broken or melted anticipator wire.

Excessive current or dead short in system. Have

a qualified service person check the system

before replacing thermostat.

3. Loose connection to thermostat or system.

Verify thermostat and system wires are securely

attached.

4. Thermostat or heating system requires

replacement or service.

Your furnace manufacturer or service person can

describe how to test the heating system to verify

it is operating correctly. If the heating system is

capable of operation and the no heat condition

persists, replace the thermostat.

5. System Switch not set to Heat.

1. Furnace Lock-Out Condition

Set System Switch to Heat and raise temp above

room temp.

Intermittent Heat

No Cool

Many furnaces have safety devices that shut the

system down when a lock-out condition occurs. If

the heat works intermittently contact the furnace

manufacturer or local service person for assistance.

1. Loose connection to thermostat or system.

Verify thermostat and system wires are securely

attached.

2. Thermostat or cooling system requires

replacement or service.

Your cooling system manufacturer or service

person can describe how to test the cooling

system to verify it is operating correctly. If the

cooling system is capable of operation and the no

cooling condition persists, replace the thermostat.

3. System Switch not set to Cool.

Set System Switch to Cool and lower temp below

room temp.

Heat, Cool or Fan Runs Constantly.

1. Possible short in wiring.

2. Possible short in thermostat.

3. Possible short in heat/cool/fan system.

Check each wire connection to the thermostat to

verify it is neatly looped under the terminals. No

extra wire should stick out from under the

terminals.

Furnace Cycles Too Fast or Too Slow

Narrow or wide temperature swing

See Step 5, Adjusting the Anticipator.

The anticipation setting is the only adjustment that

effects the heating cycle rate. If an acceptable

cycle rate is not achieved using the anticipator

contact a local service person for additional

suggestions. The location of the thermostat, size

of the Heat/Cool System and current draw can

influence the cycle rate.

Cooling Cycles Too Fast orToo Slow

(narrow or wide temperature swing)

1. Poor thermostat location for sensing room

temperature.

2. Cooling system over or undersized.

3. Excessive Current draw influencing thermostat.

The cycle rate for cooling can not be adjusted.

The location of the thermostat, size of the Cool

system and current draw can influence the cycle

rate. Contact a local service person for suggestions.

Thermostat Setting and Thermostat

Thermometer Disagree

1. Thermostat thermometer setting requires

adjustment.

The thermometer can be adjusted by using a

standard slotted screwdriver. Turn the thermom-

2. Thermostat setting lever requires calibration. eter pointer screw located inside the front cover

to change the setting. For calibrating the setting

lever contact a local heating and cooling service

person.

Adjusting Thermometer

1. Thermostat thermometer disagrees with

other room thermometers.

The thermometer on the thermostat is accurately

calibrated at our factory but you can adjusted it

by using a standard slotted screwdriver. Turn the

thermometer pointer screw located inside the

front cover to change the setting.

The Emerson logo is a

trademark and a service mark

of Emerson Electric Co.

White-Rodgers is a division

of Emerson Electric Co.