Installation
4
WCRT
and
(Supersedes PK471-3)
PK471-4
161-562767-001
OPERATION INSTRUCTIONS
DECEMBER, 1998
WCRT Weather-Corrosion
Resistant Room
Thermostat
Specifications – Table A
Maximum Rating
Temperature Switch
Range (°F) Action
Model
Description
120 Vac 240 Vac 277 Vac
Full Load Inductive
16.0A
80.0A
25.0A
125VA
12.0A
60.0A
25.0A
125VA
10.0A
55.0A
22.0A
125VA
WCRT-100
40-100
SPDT Locked Rotor
Non-Inductive
Pilot Duty
UL LISTED
Figure 1
GENERAL
Type WCRT thermostats are intended for use in harsh environ-
ments. They tolerate continuous spraying with water, high humid-
ity, airborne contaminates and moderately corrosive conditions.
The nickel plated sensing bulb is attached directly to the bottom of
the case where it is shielded from damage or accumulations of
insulating particles. The molded Noryl case is sealed at the cover
with a neoprene gasket and the adjusting knob opening is closed
with a lubricated O ring. Underwriters Laboratories has tested the
WCRT and found it meets the requirement for NEMA 4X areas.
High levels of accuracy and sensitivity, 21/2° differential, are pro-
vided by the WCRT. Switching is done by heavy duty, precision,
single stage, SPDT line voltage snap action switch. Setting is
accomplished by rotating the adjusting knob. The dial face is print-
ed with large, contrasting numbers and letters on a lustrous back-
ground for good visibility. Color coding clearly identifies the func-
tion of each conductor.
NOTICE: Type WCRT thermostats are designed for temperature
control service only. Because they do not fail safe, they should
not be used for temperature limiting duty.
WARNING: Users should install adequate back-up
controls and safety devices with their electric heat-
ing equipment. Where the consequences of failure
may be severe, back-up controls are essential.
Although the safety of the installation is the
responsibility of the user, Chromalox will be
glad to make equipment recommendations.
Principle of Operation – Control action of these thermostats is
provided through the principle of liquid volume change. With a
variation in temperature, the liquid in the sensing element expands
or contracts, causing a bellows to actuate the switching mechanism.
WARNING: Not for use in hazardous environments as
described in National Electrical Code. Failure to com-
ply can result in explosion or fire.
Applications – Automatically controls room temperature by turn-
ing electric air heaters on and off. Can be used to control the air
heaters directly, within thermostat rating. For higher ratings use
thermostat with magnetic contactor. Place thermostat on inside wall,
away from undue heating or cooling influences, about 4 feet above
the floor.
LO Setting is positive open (black to red) for heating loads and
is positive closed (black to blue) for cooling loads.
Note: It is not recommended to switch systems directly from heat-
ing to cooling and vice versa.
© 2010 Chromalox, Inc.
WIRING
Figure 3
Figure 4
WIRING DIAGRAMS
Control
Voltage
Ground
Red
Opens On
Temperature Rise
Ground
Blue
Black
Blue
Common
Red
Closes On
Temperature Rise
Black
Pilot Light
Figure 5
Line
Contactor
Ground
Blue
Red
Black
Heating Load
Pilot Light
Pilot Light
Heating Load
Pilot Light
Cooling Load
Cooling Load
Single Phase When Load or Voltage Does Not
Exceed Thermostat Rating.
Three Phase and Single Phase When Load Exceeds
Thermostat Rating.
Figure 6
Figure 7
TESTING AND OPERATION
After installation and wiring, to check the operation of heating
To check the operation of the cooling systems:
systems:
1. Disconnect power.
1. Disconnect power.
2. Place the heat/cool selector switch, if applicable, in the cool
position.
2. Place the heat/cool selector switch, if applicable, in the heat
position.
3. Adjust the setpoint ten or more degrees above the temperature
3. Adjust the setpoint ten or more degrees below the temperature
of the controlled space.
of the controlled space.
4. Restore power.
4. Restore power.
5. Slowly adjust the setpoint downward. When the setpoint
approximates the temperature of the controlled space, the cool-
ing equipment should start.
5. Slowly adjust the setpoint upward. When the setpoint reaches
the approximate temperature of the controlled space, the heat-
ing equipment should start.
Limited Warranty:
Please refer to the Chromalox limited warranty applicable to this product at
1347 HEIL QUAKER BLVD., LAVERGNE, TN 37086
Phone: (615) 793-3900
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