Instruction/ maintenance manual of the product T921B Honeywell
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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.
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.
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.
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.
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.
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.
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.
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.
An important point after buying a device Honeywell T921B (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought Honeywell T921B yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data Honeywell T921B - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, Honeywell T921B you will learn all the available features of the product, as well as information on its operation. The information that you get Honeywell T921B will certainly help you make a decision on the purchase.
If you already are a holder of Honeywell T921B, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime Honeywell T921B.
However, one of the most important roles played by the user manual is to help in solving problems with Honeywell T921B. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device Honeywell T921B along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
