Honeywell T921A User's Manual

Honeywell Thermostats User's Manual - T921A.
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60-2242—2

J. D.  •  Rev. 1-94  •  ©Honeywell Inc. 1994  •  Form Number 60-2242—2

T921A,B,E-G Proportional

Control 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 available for horizontal mount-

ing of T921A,B,E models.

■ COOL-HEAT changeover switch in the T921B.

■ Night setback mechanism and switch in the T921E.

■ A spdt (single pole double throw) Class 2 auxiliary

switch in the T921F,G, which operates at the low
(T921F) and high (T921G) end of the throttling
range.

■ A bellows element adjusts the potentiometer slider

to regulate motor operation.

■ Various temperature ranges are available.

■ All models are available with a thermometer and a

locking cover.

■ T921A

■ T921B

■ T921E

■ T921F

■ T921G

CONTENTS

Specifications ................................................. 2
Ordering Information ..................................... 2
Installation ..................................................... 4
Setting and Adjusting ..................................... 7
Operation ....................................................... 7

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