Johnson Controls A19 Series Manual

A19 Series Utility Thermostats for Farm,

Application

These temperature controls are designed to cover a
broad range of uses for heating and general purpose
requirements. See "Application" column,
"Specifications" Page 2, for typical uses. Controls
have SPST contacts which open on temperature
increase or they may be supplied in single-pole,
double-throw contact action.
Various control ranges are available to cover working
temperatures from -30 to 550° F (-34 to 288° C).
Closed tank fittings and bulb wells are available for
immersion applications.
These controls are designed for open low and open
high applications. Where critical or high value
products are to be maintained within a specific
temperature differential, a single control should not
be applied to function as both an open low and open
high control. In these applications, a separate back-
up control with alarm contacts should be wired to
indicate when the back-up control operates.
Fig. 2: Space thermostat
with Style 3 coiled bulb
and finger-tip adjusting knob.
© 1979 Johnson Controls, Inc.
Code No. LIT-125030
Industrial and Commercial Use
Temperature Controls Section A
Fig. 1: (Left) Control with external range scale,
knob adjustment. (Right) Interior of model with
adjustable differential.

Features

• Dependability -- precision snap-acting dusttight
contacts.
• Dependability -- low volume, responsive liquid
filled sensing elements.
• Wide choice of temperature control functions with
a minimum number of models.
• Precision "repeat" accuracy which is unaffected by
barometric pressure and cross ambient problems.
•
Special close differential models available.

General Description

The Series A19 is a small, compact control with
adjustable or fixed differential. Controls supplied with
adjustable differential have an internal scale plate
indicating increments of differential. The controls are
supplied with adjusting lever at minimum differential
stamped on the control. To adjust move the lever to
the differential required. Models are available with or
without external range adjustment and visible scale.
External range adjustment may be by screwdriver slot
or range adjusting knob (Fig. 2).
Master Catalog 125
Product Bulletin A19
Issue Date 0579
1