120-277 Volt Line Voltage Hazard.
Can cause serious injury or death.
Do not install thermostat unless you are a trained,
experienced electrical service technician.
Electrical Shock Hazard.
Can cause personal injury and equipment
Disconnect power supply before connecting wiring.
Use a limit control when wiring the thermostat.
If this control is replacing a control that contains
mercury in a sealed tube, do not place your old control
in the trash. Dispose of properly.
Contact your local waste management authority for
instructions regarding recycling and the proper
disposal of an old control.
When Installing This Product . . .
1. Read these instructions carefully. Failure to follow them
could damage the product or cause a hazardous condi-
2. Check the rating given in the instructions and on the
product to make sure the product is suitable for your
3. Installer must be a trained, experienced service techni-
4. After installation is complete, check out product opera-
tion as provided in these instructions.
5. Follow local codes for installation and application.
— Mount the thermostat on an approved electrical junction
— Locate the thermostat 4 to 5 ft (1.5m) above the floor on an
inside wall where the thermostat can be exposed to
average room temperature.
— Locate the thermostat away from concealed warm or cold
water pipes, light switches and dimmers, and refrigerators.
— Locate the thermostat away from drafts of hallways,
fireplaces, stairways, and fans.
When replacing an old line voltage thermostat:
— Carefully remove the old thermostat to avoid damaging the
— Check the old insulation for cracks, chips, or fraying and
apply approved electrical tape, where necessary, to ensure
T4398A,B PRECISION ELECTRIC HEATING THERMOSTAT
NOTE: Make line voltage wiring connections directly to the
leadwires installed on the thermostat, using wire con-
nectors approved for the number and size of conduc-
When using aluminum conductors, all wiring connec-
tions to the thermostat must be made to the factory-
installed lead wire, using approved CO/ALR solder-
1. Connect all wires with the thermostat cover in place. Be
sure that all wire connectors are tight. Install any secu-
rity features. See Fig. 2 and 3.
2. Pre-bend the solid conductors and push them into the
3. Remove the thermostat cover by grasping both the top
and bottom of the cover and pulling out..
Carefully handle the thermostat. Excessive pressure
can damage the control knob or sensing element.
4. Turn the dial so the setpoint indicator is at the 12 o'clock
position. (This prevents accidental damage to the dial-
stop during mounting.)
5. Using the screwdriver, secure the thermostat to the
electrical box by tightening the two mounting screws.
See Fig. 4.
6. Level the thermostat only for appearance.
7. Tighten the screws and replace the cover.
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND
OVERLOAD PROTECTION AS REQUIRED.
USE SPECIAL SERVICE CO/ALR SOLDERLESS CONNECTORS
WHEN CONNECTING ALUMINUM CONDUCTORS OR A FIRE
HAZARD MAY RESULT.
USE A SEPARATE LIMIT CONTROL IN THE HEATING APPLIANCE.
BREAKS AND REMAKES BELOW -31 F (-35 C); NORMALLY
THERMAL ACTIVATED. BREAKS ON TEMPERATURE RISE;
MAKES ON TEMPERATURE FALL.
Fig. 2. T4398A typical hookup.