Johnson Controls A19ZBA User manual

FANs 121, 125
Temperature Controls Section A
Technical Bulletin A19ZBA
Issue Date 1291
© 1991 Johnson Controls, Inc. 1
Code No. LIT-121065
Part No. 997-778
A19ZBA Type Temperature Control
Application
The A19ZBA temperature control
is designed for water chiller
applications. The control has a
range of 38 to 80°F (3 to 27°C)
with contacts that open on a
temperature drop.
A packing nut assembly, Part
No. FTG13A-600R, (Fig. 2) is
supplied with the control for
immersion applications where a
bulb well is not required. Bulb
well No. WEL14A-600R (Fig. 3)
for immersion applications is
available, if required.
All Series A19 controls are
designed for use only as
operating controls. Where an
operating control failure
would result in personal injury
and/or loss of property, it is
the responsibility of the
installer to add devices
(safety, limit controls) or
systems (alarm, supervisory
systems) that protect against,
or warn of, control failure.
Installation
When provided, follow the
equipment manufacturer’s
instructions. If instructions are
not supplied, follow the
instructions in this sheet.
!
CAUTION: Do not dent or
deform the sensitive bulb of
this control. A dent or
deformation will change the
calibration and cause the
control to cycle at a
temperature lower than the
dial setting.
Mounting
When installing the control, use
the mounting bracket as a
template and mark the location
for the two mounting screws.
Drill or punch two holes and start
the mounting screws. Place the
slot in the bottom of the bracket
under the head of the lower
mounting screw. Position the
control so the top screw is in the
top slot. Tighten both screws. It
is not necessary to level the
control except for appearance.
For closed tank applications
without a bulb well, use the
FTG13A-600R packing nut. (See
Fig. 2.) Put parts over the support
tube section of the element and
place bulb in the tank. Install the
1/2 in. NPT adapter in the tank
opening and tighten. Screw the
packing nut with the retaining
washers and packing into the
adapter as shown in Fig. 2.
!
CAUTION: Turn off the
liquid supply and relieve the
pressure before installing or
removing the bulb or bulb
well.
For applications requiring a bulb
well, install the bulb well in the tank
opening. Remove the bushing
from the bulb well and slide the
bushing over the capillary. Insert
the bulb into the bulb well and
replace the bushing. Push the
bulb into position in the bottom of
the well. Tighten the set screw in
the adapter end to hold the bulb in
position.
Wiring
!
WARNING: Disconnect the
power supply before wiring
connections are made to
avoid possible electrical
shock or damage to the
equipment.
Make all wiring connections
using copper conductors only,
and in accordance with the
National Electrical Code and
local regulations.
Fig. 1 -- A19ZBA-1 Temperature
Control. Note the mounting
bracket on the back of the case.
Note: Use the terminal screws
furnished (8-32 ×1/4 in. binder
head). Substitution of other
screws may cause problems in
making proper connections.

2 A19ZBA Technical Bulletin
Adjustments (See Fig. 4)
The A19ZBA control has a
locked low cutout stop. Pointer
"B" is locked in place with a
screw that requires a special
spanner wrench, Part No.
836-61, to change the setting.
The special wrench is supplied
with each control. To change
the low cutout stop setting,
proceed as follows:
1. Loosen screw "C" with the
special wrench.
2. Slide pointer arm "B" to the
desired cutout setting
(adjustable from
approximately 38 to 48°F
[3 to 9°C]). The cutout
setting is indicated by the
flat of arm "B."
3. Tighten screw "C."
The cut-in temperature is set by
moving knob "A" to the desired
cut-in setting. This knob
adjustment does not change the
cutout setting, but provides for a
short or long recycle time as
required by the application.
Checkout Procedure
Before leaving the installation,
observe at least three complete
operating cycles to be sure that
all components are functioning
correctly.
Repairs and Replacement
Field repairs must not be made.
For a replacement control,
contact the nearest Johnson
Controls distributor.
Controls Group
507 E. Michigan Street
P.O. Box 423 Printed in U.S.A.
Milwaukee, WI 53202