Honeywell specifications

1 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