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X-XX UL

INSTALLATION INSTRUCTIONS

®U.S. Registered Trademark
Copyright © 1999 Honeywell Inc.  •            •   All Rights Reserved

T834B; T834C; T834J

Heating-Cooling Thermostats

APPLICATION

The T834B,C,J Heating-Cooling Thermostats provide 24
to 30 Vac control in heating-cooling systems. An spdt
mercury switch makes R to W on a temperature fall for
heating, and R to Y on a temperature rise for cooling.
Integral switches control HEAT-OFF-COOL or COOL-OFF
system operation and AUTO-ON or ON-AUTO fan
operation (fan switch on T834C,J only). In heat pump and
some electric heat systems, fan operation is controlled by
the thermostat during heating. Check the electric heat
manufacturer specifications for fan control requirements. If
fan control from the thermostat is necessary in an electric
heat application, use the T834C Thermostat model (dual
fuel) with optional fan control. Jumper terminals 1 and 2 to
control fan operation from the thermostat during heating.

JUMPER

M8675

R

1

W

Y

G

2

1

1

2

2

IN ELECTRIC HEAT AND HEAT PUMP APPLICATIONS, JUMPER
TERMINALS 1 AND 2 FOR AUTOMATIC FAN CONTROL IN HEATING
 AND COOLING.

IN GAS-AND OIL-FIRED APPLICATIONS, JUMPER TERMINALS 1
AND Y FOR AUTOMATIC FAN CONTROL IN COOLING.

Fig. 1. Jumpering terminals for fan control.

RECYCLING NOTICE

This control contains mercury in a sealed tube.
Do not place control in the trash at the end of
its useful life.

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 this control, or 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 hazard-
ous 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

Damage to Heating/Cooling System Possible.
Be careful when handling wires during
installation.
Disconnect power at furnace or at main breaker/
fuse before starting installation.

Location

Locate the thermostat about 5 ft (1.5m) above the floor on
an inside wall in an area with good air circulation at
average temperature.

Do not mount the thermostat where it may be affected by:

drafts or dead spots behind doors or in corners.

hot or cold air from ducts.

radiant heat from the sun, fireplaces, or appliances.

69-0444-10

Summary of Contents for T834B

Page 1: ...ls for fan control RECYCLING NOTICE This control contains mercury in a sealed tube Do not place control in the trash at the end of its useful life 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 this control or of an ...

Page 2: ... the thermostat base See Fig 2 Carefully remove and discard the foam plastic shipping insert that protects the switch and bimetal assembly during shipping 5 Set the adjustable heat anticipator indicator to match the current draw of the primary heating control see Heat Anticipator Setting section 18 2 25 3 5 7 9 M8676 FAN SWITCH TEMPERATURE SETTING LEVER MOUNTING HOLE SYSTEM SWITCH ADJUSTABLE HEAT ...

Page 3: ...LAY IS NOT USED HEAT RELAY FAN RELAY FAN SWITCH ON AUTO COOL OFF HEAT COOL OFF HEAT SYSTEM SWITCH C1 ANTICIPATOR H1 ANTICIPATOR M1037C W O B Y G R CHANGEOVER RELAY COOL CHANGEOVER RELAY HEAT COMPRESSOR CONTACTOR Fig 5 Internal schematic and typical hookup for T834C in heat pump system with supplementary heat Fig 6 Internal schematic and typical hookup for T834C gas or oil fired systems and single ...

Page 4: ...4C with terminal for defrost relay in heat pump system Fig 9 Internal schematic and typical hookup for T834C in two transformer system H1 TEMP FALL C1 L1 HOT L2 1 1 2 2 POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED JUMPER RC AND RH IN ONE TRANSFORMER SYSTEMS HEAT RELAY COOL OFF HEAT COOL OFF HEAT SYSTEM SWITCH C1 ANTICIPATOR M11746 W RH L1 HOT L2 1 FAN RELAY FAN SWITCH ...

Page 5: ...ELAY FAN RELAY COOL OFF HEAT COOL OFF HEAT SYSTEM SWITCH C1 ANTICIPATOR H1 ANTICIPATOR M6108A W Y G R NO FAN SWITCH Fig 10 Internal schematic and typical hookup for T834B in standard heating cooling system with no fan switching TEMP FALL C1 L1 HOT L2 1 1 POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED COOL RELAY P RELAY FAN SWITCH ON AUTO COOL OFF COOL OFF SYSTEM SWITCH C...

Page 6: ...ired control point on the temperature scale The same lever controls both heating and cooling On models with temperature range stops temperature setting lever can be moved only between the two temperature range stops HEATANTICIPATOR SETTING IMPORTANT The T834 Thermostat has an adjustable heat anticipator and will operate properly ONLY IF THE ANTICIPATOR IS ADJUSTED TO MATCH THE CURRENT DRAW OF THE ...

Page 7: ...ed by the thermostat in both heating and cooling T834J With the system switch set at OFF and the fan switch at ON the fan should run continuously Move the fan switch to AUTO The fan operation is controlled by the thermostat Electric Systems with auto fan in heat Set adjustable anticipator to combined current draw of heating and fan relays Other Systems without auto fan in heat Set adjustable antic...

Page 8: ...t the same setting as the thermometer Remove cover 2 Insert Honeywell part no 104994A Calibration Wrench order separately onto the hex nut under the coil See Fig 13 Holding the setting lever so it does not move turn the wrench clockwise until the mercury rolls to the right end of the tube Remove wrench and replace cover To ensure accurate temperature control do not touch or breathe on bimetal or t...

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