Pentax T8775C, T8775A User Manual

Non-Programmable Thermostats

The T8775A,C Thermostats provide single-stage temperature control for 24V systems. The T8775A,C models include a thermostat, wallplate (for wiring and mounting thermostat), mounting screws, wall anchors, and a 4074 FAB resistor.

MERCURY NOTICE

If this control 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.

INSTALLATION

When Installing this Product…

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

2. Check the ratings given in the instructions and on the product to make sure the product is suitable for your application.

3. Installer must be a trained, experienced service technician.

4. After installation is complete, check out product operation as provided in these instructions.

CAUTION

Electrical Shock or Equipment Damage Hazard. Can shock individuals or short equipment circuitry.

Disconnect power supply before installation.

T8775A,C

The Digital Round

INSTALLATION INSTRUCTIONS

Location

Install the thermostat about 5 ft (1.5m) above the floor in an area with good air circulation at average temperature. Do not install the thermostat where it can be affected by: — drafts or dead spots behind doors and in

corners. — hot or cold air from ducts. — radiant heat from the sun or appliances. — concealed pipes and chimneys. — unheated (uncooled) areas such as an outside

wall behind the thermostat.

Mounting Wallplate to Wall

Mount the T8775A,C wallplate, with the screws provided. See Fig. 1.

WALL ANCHORS (2)

WALL PLATE

WIRING HOLE

1 INCH SCREW (2)

1 WHEN USING WALL ANCHORS, DRILL 3/16 IN. HOLES FOR DRYWALL, 7/32 IN. HOLES FOR PLASTER.

Fig. 1. Mounting wallplate to wall.

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™

M19499

T8775A,C THE DIGITAL ROUND™ NON-PROGRAMMABLE THERMOSTATS

Wiring

IMPORTANT

Use 18-gauge wire to wire the T8775A,C Thermostats.

All wiring must comply with local electrical codes and ordinances. Disconnect the power supply to prevent electrical shock or equipment damage.

Refer to Fig. 2 through 6 for typical wiring hookups.

Fig. 4. Typical hookup of T8775C in heat-cool system

HEATING

RELAY OR

VALVE COIL

1 POWER SUPPLY. PROVIDE DISCONNECT MEAN AND OVERLOAD PROTECTION AS REQUIRED.

2 FACTORY INSTALLED JUMPER.

with single transformer.

G Y W

COMPRESSOR

CONTACTOR

FAN

RELAY

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POWER SUPPLY. PROVIDE DISCONNECT MEAN AND OVERLOAD PROTECTION AS REQUIRED.

HEATING

RELAY OR

VALVE COIL

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Fig. 2. Typical hookup of T8775A in a heat-only system.

G Y

1 POWER SUPPLY. PROVIDE DISCONNECT MEAN AND OVERLOAD PROTECTION AS REQUIRED.

2 FACTORY INSTALLED JUMPER.

Fig. 3. Typical hookup of T8775C in heat-only system

HEATING

RELAY OR

VALVE COIL

with fan.

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FAN

RELAY

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COMPRESSOR

CONTACTOR

HEATING

RELAY OR

VALVE COIL

1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

REMOVE FACTORY INSTALLED JUMPER BETWEEN R AND RC.

Fig. 5. Typical hookup of T8775C in heat-cool system

Fig. 6. Typical hookup of T8775C in single-stage heat

with two transformers.

COMPRESSOR

CONTACTOR

RELAY

1 POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

2 FACTORY INSTALLED JUMPER. 3 USE A JUMPER WIRE (NOT SUPPLIED) TO CONNECT W TO

4 USE EITHER O OR B FOR HEAT PUMP CHANGEOVER.

pump system.

CHANGEOVER

FAN

RELAY

HEAT

VALVE

FAN

COOL

CHANGEOVER

VALVE

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T8775A,C THE DIGITAL ROUND™ NON-PROGRAMMABLE THERMOSTATS

CUSTOMIZE THERMOSTAT

Setting Fuel Switch (T8775C only)

The fuel switch is preset at the factory in the F position. See Fig. 7. This is the correct setting for gas or oil systems. If the T8775C is being installed on an electric heat system, or a heat pump, set the switch to the E position. The E setting allows the fan to turn on immediately with the heating equipment in a system where the G terminal is connected.

FUEL SWITCH

Fig. 7. Fuel switch.

DIP Switch

To adjust the heat cycle rate or the Fahrenheit/Celsius indication, locate DIP switch 1, 2 and 3 on the back of the thermostat. See Fig. 8.

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Table 1. Heat Cycle Rate.

Cycles

DIP

Switch

DIP

Switch

Heating System

Steam, Gravity 1 On On

High Efficiency Warm Air (90%+ efficiency), Hot Water, Heat Pump

Gas or Oil Warm Air (factory setting)

Electric Warm Air 9 On Off

In Floor Radiant Heat Check with manufacturer

Per

Hour

3OffOn

6OffOff

for recommended cycle rate.

Fahrenheit/Celsius Indication

Use DIP switch 3 to set the desired temperature indication. See Table 2.

Table 2. Temperature Indication.

Fahrenheit/Celsius

Display DIP Switch 3

Fahrenheit (factory setting) Off

Celsius On

Mounting Thermostat to Wallplate

ENGAGE TABS AT BOTTOM OF THERMOSTAT AND WALL PLATE.

PRESS UPPER EDGE OF CASE TO LATCH

1 2 3

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Fig. 8. DIP switch.

Set Heat Cycle Rate

Use DIP switches 1 and 2 to set the heat cycle rate. See Table 1.

M19498

Fig. 9. Mounting thermostat to wallplate.

OPERATION

Setting SYSTEM and FAN Switches (T8775C only)

System and fan settings are controlled manually by using the switches located at the top of the thermostat. See Fig. 10.

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T8775A,C THE DIGITAL ROUND™ NON-PROGRAMMABLE THERMOSTATS

BACKLIGHT ON

(T8775C ONLY)

(T8775C ONLY) SELECTS COOL/OFF/HEAT

DISPLAYS ROOM OR SET TEMPERATURE

SELECTS ON/AUTO

ROOM

SHOWS THAT THE

SET

CURRENT ROOM TEMPERATURE IS DISPLAYED.

SHOWS THAT THE CURRENT TEMPERATURE SETPOINT IS DISPLAYED.

DISPLAYS AND ADJUSTS TEMPERATURE SETPOINT/TURNS

Fig. 10. T8775 Thermostat (features and operation).

SYSTEM Switch

Heat: The thermostat controls the heating

system. Off: Both heating and cooling systems are off. Cool: The thermostat

system.

controls the cooling

FAN Switch

Auto: The fan only runs with the heating and

cooling system. On: The fan runs continuously. Use for

improved air circulation.

CHECKOUT

NOTE: Temperature setpoint range is 40°F to 90°F

(4°C to 32°C) in heating and 45°F to 99°F (7°C to 37°C) in cooling.

Heating

1. Slide the SYSTEM switch to Heat and the FAN switch to Auto (T8775C only).

2. Raise the temperature setpoint several degrees above the room temperature.

3. A flame will appear in the display and the heat should turn on.

4. Lower the temperature setpoint below the room temperature.

5. The flame will disappear from the display and the heat should turn off.

Cooling (T8775C only)

CAUTION

Low Temperature Hazard. Operating at too low of an outdoor temperature may cause compressor damage.

Do not operate cooling if outdoor temperature is below 50°F (10°C). Refer to manufacturer’s recommendations.

NOTE: If a call for cooling is made before the com-

pressor has been off for five minutes, or if a power interruption occurs while the compressor is running, the thermostat will go into a five-minute delay to protect the compressor. The snowflake will flash during this delay.

1. Slide the SYSTEM switch to Cool and the FAN switch to Auto.

2. Lower the temperature setpoint several degrees below the room temperature.

3. After approximately five minutes, the thermostat will display a solid snowflake and the cooling should turn on.

4. Raise the temperature setpoint above the room temperature.

5. The snowflake will disappear from the display and the cooling should turn off.

Fan

1. Slide the SYSTEM switch to Off and the FAN switch to On. The fan should run continuously.

2. Slide the FAN switch to Auto. The fan should turn off.

M1952

Automation and Control Solutions

Honeywell International Inc. Honeywell Limited-Honeywell Limitée 1985 Douglas Drive North 35 Dynamic Drive Golden Valley, MN 55422 Scarborough, Ontario

69-1677EF J.S. 6-03 Printed in Hungary www.honeywell.com/yourhome

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