Honeywell CT8775A User Manual

CT8775A,C

THE DIGITAL ROUND™ NON-PROGRAMMABLE THERMOSTATS

OWNER’S GUIDE

CT8775A Heat Only Thermostat (20 to 30 Vac) and CT8775C Heating-Cooling Thermostat (20 to 30 Vac)

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Contents

Step 1. Prepare for Installation .................................................................................................................................. 3

Step 2. Remove Old Thermostat ............................................................................................................................... 4

Step 3. Special Installations........................................................................................................................................ 4

Step 4. Label Thermostat Wires................................................................................................................................. 5

Step 5. Separate Wallplate from Thermostat.............................................................................................................. 5

Step 6. Mount Decorator Cover Plate and Thermostat Wallplate............................................................................... 5

Step 7. Wire Wallplate Terminals................................................................................................................................ 8

Step 8. Customize the Thermostat............................................................................................................................. 10

Step 9. Mount the Thermostat.................................................................................................................................... 11

Step 10. Set the System and Fan Switches ............................................................................................................... 12

Step 11. Operating the Thermostat............................................................................................................................. 13

Step 12. Check Operation of Heating and/or Cooling System ................................................................................... 13

If You Have A Problem ............................................................................................................................................... 15

Wiring Diagrams......................................................................................................................................................... 16

Enjoy the benefits of The Digital Round

Thermostat by Honeywell.

• Simple to use. Turn the dial to adjust the temperature setting.

• Large easy-to-read display. The temperature reading is easily seen from a distance.

• Backlit display. On-demand backlighting makes it easy to read the display in a dark room or hallway.

• No batteries required. The temperature setting is held permanently in memory in the event of a power failure.

This manual answers many of the questions that can arise as you become familiar and comfortable with your Honeywell thermostat — the state of the art in home comfort controls.

Read these instructions carefully. Failure to follow these instructions can damage the product or cause a hazardous condition.

MERCURY NOTICE

If this thermostat is replacing a control that contains mercury in a sealed tube, do not place your old control in the trash. Contact your local waste management authority for instructions regarding recycling and the proper disposal of an old control containing mercury in a sealed tube.

TYPICAL LOCATION OF A MERCURY SWITCH IN A THERMOSTAT

ROOM

SET

M19582

MERCURY SWITCH

M10614

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STEP 1. PREPARE FOR INSTALLATION

❑ Check Table 1, the compatibility chart, to make sure the thermostat is compatible with your system. If your system

is not compatible, call Honeywell Customer Care, toll-free, 1-800-468-1502.

Table 1. Compatibility Chart.

System Type

CT8775A

Gas or Oil Warm Air Yes Yes

Electric Warm Air No Yes

Compatibility with

Gas or Oil Hot Water

Yes

Gas or Oil Steam Yes Yes

Gas or Oil Gravity Yes Yes

Gas Millivolt No No

Electric Air Conditioning No Yes

Baseboard Electric (120/240 line volt)

No No

Single Stage Heat Pump No Yes

Multistage Heat Pumps/Multistage Equipment No No

Compatible with 2-wire Honeywell zone valves. Not compatible with Taco zone valves and 2- or 3-wire White-

Rodgers zone valves (No. 1311 and 1361).

Not compatible with any 120/240 volt system.

Package Contents

• Thermostat • Decorator cover plate • Screws and wall anchors

• Wiring labels • Owner’s Guide

Compatibility with

CT8775C

Yes

Tools for Installation

• Screwdriver • Drill • Hammer

• Needle nose pliers • Drill bits (3/16 in. drywall,

7/32 in. plaster)

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STEP 2. REMOVE OLD THERMOSTAT

❑ Test your heating and cooling systems to make sure they work properly. If either system does not work, contact

your local heating/air-conditioning dealer. To avoid compressor damage, do not operate the cooling system when outdoor temperature is below 50°F (10°C).

❑ Turn off power to the system at the furnace or the fuse/circuit breaker panel. ❑ Carefully unpack your new thermostat and decorator cover plate. Save package of screws, instructions, and

receipt.

❑ Remove the cover from the old thermostat. If the cover does not snap off when pulled firmly from the top or bottom,

check for a screw or screws that may be used to lock on the cover.

❑ Loosen the screw or screws (if present) holding the thermostat to the wallplate and lift the thermostat away. Do not

disconnect wires.

STEP 3. SPECIAL INSTALLATIONS

Read this section if you are replacing:

• A thermostat that has wires connected to C or C1 terminals.

• A thermostat that is connected to six or more wires.

• A thermostat that is connected to three wires on a warm air heating only system.

• A thermostat that is connected to three wires on a zoned hot water heating system.

NOTE: If none of the special installations apply to your particular application, please skip to Step 4.

Replacing a thermostat that has wires connected to C or C1 terminals

If you are replacing a thermostat that has one or two wires connected to C or C1 terminals, do not allow them to touch, or you can damage the transformer. Wrap the wires separately using electrical tape. Place the wires where they will not interfere with the operation of the new thermostat. Continue with the installation at Step 4.

Replacing a thermostat that is connected to six or more wires

If you are replacing a thermostat that is connected to six or more wires (excluding wires connected to C or C1 terminals), you may have a multistage heat pump or other multistage system. If you have either one of these systems, return the product to the place of purchase. This thermostat is not compatible with these systems. For information about which thermostats will work with your system, call Honeywell Customer Care, at 1-800-468-1502.

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Replacing a thermostat that is connected to three wires on a warm air heating only system

If you are replacing a thermostat that is connected to three wires on a warm air heating only system and could turn the fan on by setting the thermostat fan switch to ON, the CT8775C Thermostat will work with your system. Continue with the installation at Step 4. If you purchased a CT8775A thermostat, return the product to the place of purchase. The CT8775A thermostat is not compatible with this application.

Replacing a thermostat that is connected to three wires on a zoned hot water heating system

If you are replacing a thermostat that is connected to three wires on a zoned hot water heating system, the CT8775A,C thermostats will only work if an isolation relay is installed. For details, call your local heating and/or cooling contractor.

STEP 4. LABEL THERMOSTAT WIRES

❑ Disconnect the wires from the old thermostat. As you disconnect each wire, attach

the enclosed labels with the old terminal designation. Wrap the wires around a pencil as shown to keep them from falling back into the wall.

STEP 5. SEPARATE WALLPLATE FROM THERMOSTAT

❑ Remove cover from thermostat. Separate the wallplate from the

thermostat by placing your thumb on the top between the wallplate and the thermostat and pulling the thermostat away from the wallplate. See the illustration at the right.

STEP 6. MOUNT DECORATOR COVER PLATE AND THERMOSTAT WALLPLATE

❑ The decorator cover plate and wallplate can be mounted directly

on the wall or onto an electrical box.

❑ To mount directly to the wall, see Fig. 1. ❑ To mount onto an electrical box, see Fig. 2.

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COVER REMOVED

THERMOSTAT

WIRES THROUGH WALL OPENING

M5136

WALL PLATE

M19492

Mount Decorator Cover Plate (Optional) and Wallplate Directly to Wall

❑ If using the decorator cover plate, pull the wires through

the wiring hole on the decorator cover plate. Position the decorator cover plate against the wall so that the UP indicator in the middle of the decorator cover plate is pointing up.

❑ Position the wallplate:

❑ If using the decorator cover plate, pull the wires

through the wiring hole on the wallplate and place the wallplate over the decorator cover plate. Turn the wallplate until the wiring holes are aligned and the two screw holes on the left and right side of the wallplate line up with the screw holes on the decorator cover plate. You will be inserting the screws through these holes into the wall.

❑ If attaching the wallplate directly to the wall, pull the

wires through the wiring hole on the wallplate and position it so that the UP indicator on the wallplate is pointing up.

❑ Use a pencil to mark the center of the screw holes on the

left and right sides of the wallplate.

❑ Remove the wallplate and decorator cover plate (if used)

and drill two 3/16 in. holes in the wall (if drywall) at the locations you marked. For materials such as plaster, drill 7/32 in. holes where marked. Gently tap the provided anchors into the drilled holes until they are flush with the wall.

❑ Pull the wires through the wiring holes and reposition the

decorator cover plate (if used) and wallplate over the screw holes.

❑ Attach the decorator cover plate (if used) and wallplate to

the wall with two 1-in. screws.

DECORATOR COVER PLATE

WALL PLATE

1 INCH SCREW (2)

WIRING HOLES

Fig. 1. Mount decorator cover plate (optional) and

wallplate directly to wall (heating-cooling wallplate

WALL ANCHORS (2)

shown).

M19493

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