Chromalox PK471-4 Thermostat User Manual
Contents
1. 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 2010 Chromalox Inc 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 s 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 explosi2. Chromalox Installation and OPERATION INSTRUCTIONS Chromalox CAT NO Model Temperature Range F SERVICE REFERENCE ovisio 4 seemon WCRT PK471 4 161 562767 001 SALES REFERENCE Supersedes PK471 3 pat DECEMBER 1998 WCRT Weather Corrosion Resistant Room Thermostat Specifications Table A Maximum Rating 120 Vac 240 Vac 277 Vac Switch Action Description WCRT 100 6 Figure 1 UL LISTED 16 0A 12 0A 10 0A 80 0A 60 0A 55 0A 25 0A 25 0A 22 0A 125VA 125VA 125VA Full Load Inductive Locked Rotor Non Inductive Pilot Duty 40 100 SPDT 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
3. X Heating Load Pilot Light Senp ARR ARR VVV V LLUIINyY LVAU GLouIINY l vad Dhaglt Fuss Who Luau vi VON taye Luve Nor Imos Fhase and Shaglt Fliuvv Wien Luda Enooud Exceed INernnostal Kalliy Iherniostal Katitiy Figure 6 Figure 7 1 2 3 TESTING AND OPERATION After installation and wiring to check the operation of heating systems Disconnect power Place the heat cool selector switch if applicable in the heat position Adjust the setpoint ten or more degrees below the temperature of the controlled space Restore power Slowly adjust the setpoint upward When the setpoint reaches the approximate temperature of the controlled space the heat ing equipment should start To check the operation of the cooling systems 1 2 3 Disconnect power Place the heat cool selector switch if applicable in the cool position Adjust the setpoint ten or more degrees above the temperature of the controlled space Restore power Slowly adjust the setpoint downward When the setpoint approximates the temperature of the controlled space the cool ing equipment should start Limited Warranty Please refer to the Chromalox limited warranty applicable to this product at http www chromalox com customer service policies termsofsale aspx Chromalox PRECISION HEAT AND CONTROL 1347 HEIL QUAKER BLVD LAVERGNE TN 37086 Phone 615 793 3900 www chromalox com
4. on 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 MOUNTING Note Do not mount control where it will be subject to vibration or shock Do not mount adjacent to a large magnetic contactor as vibration and shock will cause thermostat to interact erratically resulting in chattering of the contactor 1 The proper location of a heavy duty room thermostat is impor tant to assure good performance Locate where air circulates freely Never install on or near outside wall Keep away from windows or doors Do not locate too close to strong light or other false source of heat such as sunlight steam lines etc If electrical conduit leads into cooler or warmer room plug up space around wires in the conduit with rock wool 2 Use sheet metal or wood screws through the four 1 4 diameter mounting holes in the housing to mount control See Figure 2 3 WARNING Any deformations of bulb or capillary that result in leakage of fluid from control ren ders control inoperative Sou Dimensions 57 w amp She q 1 4 Dia 4 Places Figure 2 WIRING WARNING Hazard of Electrical Shock Disconnect all power before wiring or servicing this control 1 Electric wiring must be installed in acco
5. rdance with the National Electrical Code and with local codes by a qualified person WARNING Use copper conductors only 2 Entrance for wiring is provided by one 1 inch conduit hole in top of housing Wiring to control housing should be in mois ture resistant conduit 3 Remove cover by removing four screws see Figures 3 and 4 4 The Chromalox type WCRT thermostat has an enclosed SPDT switch and may be wired to open on temperature rise black to red or to close on temperature rise black to blue See Figure 5 5 Connect wires according to wiring diagrams Figures 6 and 7 Note Electrical connections should be made with generous loops of wire approximately 6 per lead 6 Replace cover and cover screws Tighten screws to 4 5 inch pounds torque 7 Note If load amperage or voltage rating exceeds switch rating and for 3 phase loads a contactor must be used Contactor and wiring to be supplied by customer see Figure 7 WARNING Non metallic enclosure requires the use of ground type hub and a jumper wire for ground ing the thermostat NOTICE Thermostat is UL Listed for NEMA 4X areas For it to retain this listing the sealed conduit hub must also be so listed Example Myers Nos ST 1 ST 2 STR 1 STR 2 or engineering equivalent Figure 3 WIRING Figure 4 WIRING DIAGRAMS Control Voltage Opens On Temperature Rise Commor Closes On Temperature Kise Figure 5 Pilot Light Pilut Light
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