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69-0444—10

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T834B; T834C; T834J HEATING-COOLING THERMOSTATS

SETTINGS AND ADJUSTMENT

System and Fan Switching

T834B

The T834B features a SYSTEM switch for control of the
heating-cooling system.

The SYSTEM switch controls system operation as follows:

HEAT: Heating system only operates.
OFF: Both heating and cooling control systems are

disconnected.

COOL: Cooling system only operates.

The fan operates in response to the plenum fan control in
heating; fan operates with cooling equipment in cooling.

T834C

The T834C features SYSTEM and FAN switches for
control of the heating-cooling and fan systems.

The SYSTEM switch controls system operation as follows:

HEAT: Heating system only operates.
OFF: Both heating and cooling control systems are

disconnected.

COOL: Cooling system only operates.

The FAN switch controls fan operation as follows:

AUTO: for conventional (gas, oil or central electric heat)

systems, the fan operates in response to the plenum
fan control in heating; fan operates in response to
the thermostat in cooling. For heat pump systems,
the fan operates in response to the thermostat in
both heating and cooling.

ON: The fan runs continuously.

T834J

The T834J features SYSTEM and FAN switches for
control of the cooling and fan systems.

The SYSTEM switch controls system operation as follows:

OFF: Cooling control system is disconnected.
COOL: Cooling system operates.

The FAN switch controls fan operation as follows:

AUTO: Fan operates in response to the thermostat in

cooling.

ON: Fan runs continuously.

NOTE:

Some electric heat systems require control of fan
operation from the thermostat. These systems
require a thermostat with control of fan operation
in response to a call for heating or cooling.

To switch positions, use thumb and index finger to slide
lever to desired position. Switch lever must stop directly
over desired function indicator mark for proper circuit
operation.

Temperature Setting

Push the temperature setting lever to the desired 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.

HEAT ANTICIPATOR 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 PRIMARY
CONTROL. Use this thermostat only on systems
with current draws that fall within the range of the
heat anticipator. Do not use this device on
Powerpile® (millivolt) Systems.

Conventional Systems

A current rating is usually stamped on the nameplate of
the primary control. Set the adjustable heat anticipator
indicator to match the value given on the nameplate.

If the current rating is not available, proceed as follows to
determine the rating:

1. Turn off power.
2. Wire thermostat, except for connection to

W terminal, but do not mount it on the wall.

3. Connect ammeter between W wire and

W terminal on the thermostat.

4.  Prepare the system for operation.
5. Turn on power.
6. Turn system switch to heat.
7. Increase thermostat setpoint as necessary to get

system operating.

8. With the system operating through the ammeter,

wait one minute, then read the ammeter.

9. Turn the system switch to OFF, and turn off

power.

10. Adjust the heat anticipator to match the reading

on the ammeter.

11. Disconnect the ammeter, reconnect the W wire,

and mount the thermostat. Continue with system
checkout.

NOTE:

The heat anticipator may require further adjust-
ment for best performance. To lengthen burner-
on time, move the indicator in the direction of the
longer arrows but not more than one-half scale
marking at a time. To shorten burner-on time,
move indicator in opposite direction.

Heat Pump Systems
(for about 3 cycles per hour)

Using B Terminal

Set adjustable anticipator to 130 percent of combined
current draw of compressor and fan relays.

Using O Terminal

Set adjustable anticipator to maximum scale setting. Limit
combined load current of compressor and fan relays to
0.8 amp, because cooling anticipator provides anticipation
during heat cycle in these hookups.

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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