Chromalox WT-121 Installation Instructions

control service only. Because they do not fail safe, they should not be used for temperature limiting duty. Users should install adequate back-up controls and safety devices with their electric heating 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 recom- mendations. Not for use in hazardous environments as described in the National Electrical Code. Failure to comply can result in explosion or fire. Thermostat Location 1. Mount in any standard electrical outlet box. Use of extra deep box (3” x 2” x 31/2”) makes for easier wiring. 2. Locate outlet box about 5’ above floor on inside wall. 3. Box location should be representative of the area to be controlled. Avoid locations that are subject to drafts or false external heat (such as solar radiation, direct heat from heaters, etc.). Insure that the wall selected is capped to prevent drafts within the wall. General 4.72" (110) Front View 2.14" (54) Side View 2.86" (73) Model Temp. Range (˚F) Contacts Maximum Rating 24V AC 120V AC 208V AC 240V AC 277V AC Pilot Duty WT-121 45-75 SPST 22 amps or 528 total watts 22 amps or 2640 total watts 22 amps or 4575 total watts 22 amps or 5280 total watts 18 amps or 5000 total watts 125V AC (use with AC contactor) WT-122 45-75 DPST 1. Cut lead wires protruding from outlet box approximately 4” from wall surface and strip end insulation 1/2”. 2. Always test the heater circuit for electrical shorts before connecting the thermostat. 3. Remove thermostat knob and front cover. 4. Using wire-nuts or other local code approved devices, connect load and line wires to appropriate color coded thermostat wires. (See wiring diagrams below.) 5. Mount the thermostat to the outlet box using the screws provided. Take care not to push or damage the bimetal sensing element during installation. 6. Replace the thermostat front cover and knob. Any knob temperature setting below 50°F may re- sult in freezing. Installation

fore wiring or servicing this control. Electric wiring to heater must be installed in accordance with National Electrical Code and with local codes. Use copper conductors only. Connect wires according to wiring diagrams (Figures 1 & 2). Note: Electrical connections should be made with generous loops of wire — approximately 6” per lead. Note: If load amperage or voltage rating exceeds switch rat- ing, a contactor must be used. Wiring Figure 1 Figure 2 Note: 1. Connect anticipator lead (white) in parallel with heater. 2. Thermostat performance will be degraded if anticipator con- nection is omitted. Note: 1. Suitable for control of one heating load only. 2. No separate connection required for heat anticipation. 3. Temperature control switch is located on right hand side when thermostat is viewed from the rear.

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