Chromalox PK471-4 User Manual

Installation, Wcrt weather-corrosion resistant room thermostat, Operation instructions

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(Supersedes PK471-3)

PK471-4

WCRT

161-562767-001

DECEMBER, 1998

4

OPERATION INSTRUCTIONS

Installation

and

WCRT Weather-Corrosion

Resistant Room

Thermostat

© 2010 Chromalox, Inc.

Temperature Switch

Maximum Rating

Model

Range (°F)

Action

Description

120 Vac

240 Vac

277 Vac

Full Load Inductive

16.0A

12.0A

10.0A

WCRT-100

40-100

SPDT

Locked Rotor

80.0A

60.0A

55.0A

Non-Inductive

25.0A

25.0A

22.0A

Pilot Duty

125VA

125VA

125VA

Specifications – Table A

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, 2

1

/

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.
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.

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.

W

WA

AR

RN

NIIN

NG

G:: 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.

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.

Figure 1

UL LISTED

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