Honeywell T921B manual

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Table of contents for the manual

  • Page 1

    1 60-2242—2 J. D. • Rev. 1-94 • ©Honeywell Inc. 1994 • Form Number 60-2242—2 T921A,B,E-G Pr oportional Contr ol Thermostats T921 Thermostats provide 3-wire, low voltage proportional control for Series 90 (135 ohm) valve motors, damper motors, and balancing relays in heating or cooling system applications. ■ Accessory faceplates availab[...]

  • Page 2

    60-2242—2 2 T921A,B,E-G SPECIFICATIONS • ORDERING INFORMATION Ordering Inf ormation When purchasing replacement and modernization products from your TRADELINE ® wholesaler or your distributor, refer to the TRADELINE ® Catalog or price sheets for complete ordering number or specify— 1. Model number. 2. Scale range. 3. Accessories, if desired[...]

  • Page 3

    3 60-2242—2 T921A,B,E-G SPECIFICATIONS Fig. 1—T921 approximate installation dimen- sions in in. [mm]. SETTING ADJUSTMENT KNOB 1 1 M9107 3 [84] 5 16 5 [145] 11 16 5 [137] 3 8 7 [194] 5 8 1 16 3 [78] 5 16 3 [84] 3 8 3 [86] 5 16 5 [135] 1 4 2 [57] FOR VERTICAL CONDUIT BOX (2) HORIZONTAL CONDUIT BOX ACCESSORY ADAPTER PLATE (127246A) FOR MOUNTING ON[...]

  • Page 4

    60-2242—2 4 T921A,B,E-G INSTALLATION Installation ! CA UTION Disconnect power supply before installation to prevent electrical shock and equipment damage. WHEN INSTALLING THIS PRODUCT… 1. Installer must be a trained, experienced service tech- nician. 2. All wiring must comply with applicable electrical codes, ordinances and regulations. 3. Do n[...]

  • Page 5

    5 60-2242—2 T921A,B,E-G INSTALLATION Fig. 4—Vertical mounting of T921A,B,E-G Thermostats on horizontal conduit box. T921A,B,E Thermostats can also be mounted horizontally on vertical conduit box using add-on faceplate. (Do not mount T921F,G horizontally.) HONEYWELL 80 70 60 60 70 80 90 NOTE: ACCESSORY FACEPLATE FOR USE WHEN THE THERMOSTAT IS MO[...]

  • Page 6

    60-2242—2 6 Fig. 7—Typical wiring diagram for T921B. T921A,B,E-G INSTALLATION • SETTING AND ADJUSTING Fig. 9—Typical wiring diagram for T921F. L1 (HOT) L2 1 1 SERIES 90 MODULATING MOTOR T921F M5993 CLASS 2 POWER SUPPLY. INTERCHANGE B AND W CONNECTIONS TO REVERSE DIRECTION OF MOTOR TRAVEL. USE FOR CLASS 2 CIRCUITS. MAKES R TO B ON TEMPERATUR[...]

  • Page 7

    7 60-2242—2 T921A,B,E-G SETTING AND ADJUSTING • OPERATION This switch energizes a heater that offsets the ther- mostat approximately 10 ° F [6 ° C], lowering the temperature for night operation. Leave this switch in the OFF position for normal operation; turn it to the ON position for lower night time temperature. CALIBRATION IMPORTANT: Do no[...]

  • Page 8

    60-2242—2 8 Fig. 13—T921G auxiliary switch operation. T921A,B,E-G OPERATION␣ T921B 1. Place the changeover switch (see Fig. 11) in the HEAT position and follow steps 1 through 3 of the T921A procedure. 2. Move the switch to the COOL position and repeat steps 1 through 3 of the T921A procedure. 3. If the valve or damper responds properly to th[...]