Installation Sheets Manual
Temperature Controls Section
Technical Bulletin
Issue Date
121
A
A19
0588
A19 Series Immersion Hot Water
Controls -- SPST and SPDT
Application
These controls are used on hot
water boiler systems. Typical
applications include:
•
high temperature cutout
control
•
operating control to maintain
hot water supply
•
circulator or unit heater
control
•
! 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.
1.
combined operating and
circulator control
Drain the system to a level
below tapping.
2.
The controls have an adjustable
range and adjustable or fixed
differential. They are also
available with lockout that
requires manual reset.
Remove bulb well from the
control by loosening set
screws in the hex nut.
3.
Place a small amount of
pipe dope on the bulb well
threads to prevent leakage.
4.
Turn bulb well securely into
the boiler tapping.
All Series A19 temperature
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
Follow equipment
manufacturers’ instructions, if
provided. Mount the control in
top or side boiler tappings.
Specifications
Fig. 1 -- An A19 Hot Water
Control less cover with
adjustable differential.
To install:
5.
Insert the bulb into well
applying a firm pressure to
be sure the bulb is at bottom
of well. Tighten set screws.
a.
! CAUTION: Be sure that
unobstructed depth is
sufficient so bulb well will
not make metal-to-metal
contact. The bulb well must
be completely submerged-avoid mounting where it
might be partly above the
operating liquid level or
surrounded by an air
pocket.
On remote bulb models,
remove bushing from
the bulb well. Insert
bulb into well. Slide
bushing over capillary
and push into bulb well.
Tighten set screws.
! CAUTION: For Remote
Mounting Models Only. On
rough mounting surfaces
use the top two mounting
holes only. When these
controls are mounted on an
uneven surface using
screws in all four holes, the
case can be twisted enough
to affect the control’s
calibration and operation.
Wiring
! CAUTION: Disconnect
power supply before wiring
connections are made to
avoid possible electrical
shock or damage to
equipment.
© 1988 Johnson Controls, Inc.
Form 997-529-7
Code No. LIT-121020
1
3.
All wiring should conform to the
National Electrical Code and
local codes. Single-pole,
double-throw models should be
wired as shown in Fig. 3. Red is
the common terminal. Use
copper conductors only.
! CAUTION: Use terminal
screws furnished (8-32 ×
1/4 in. binder head).
Substitution of other screws
may cause problems in
making proper connections.
Adjustments
Dial settings normally indicate
the cutout setting unless
otherwise specified by the
equipment manufacturer.
Models with SPDT contacts are
normally set so the red
(common) to blue contacts open
at the dial setting on a rise in
temperature.
Rotate adjusting knob to raise or
lower both the cutout and cut-in
settings.
Convertible adjustment models
can be field converted from
concealed screwdriver slot
adjustment to knob adjustment
or external screwdriver slot
adjustment. They are supplied
with a snap-in plug in the cover
to provide concealed
screwdriver slot adjustment. For
knob adjustment remove the
snap-in plug and press the knob
onto the slotted shaft. For
external screwdriver slot
adjustment remove the snap-in
plug.
Models with adjustable
differential have a differential
scale plate (see Fig. 1) with a
multiplier shown. For example,
when “MIN.” differential is 6F°
(3.3C°), then x2 is 12F° (6.6C°),
x3 is 18F° (9.9C°), etc. The
controls are supplied with
adjusting lever at minimum
differential stamped on the
control. To adjust, move the
lever to the differential required.
Loosen the cutout stop
screw, slide the screw to the
front of the temperature
control against the plastic
step behind the dial and
tighten the screw.
(See Fig. 4.)
Note: Sometimes an exact
stop setting is not possible
and the stop must be set to
the closest step
corresponding to the dial
setting.
Checkout Procedure
Before applying power, make
sure installation and wiring
connections are according to job
specifications.
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 wholesaler.
High Temperature Cutout
Stop
Fig. 2 -- An A19 with
convertible adjustment has a
snap-in plug in the cover and a
knob for field installation.
Controls Group
507 E. Michigan Street
P.O. Box 423
Milwaukee, WI 53201
2 A19 Technical Bulletin
The high temperature cutout
stop is an integral part of these
hot water controls and can be
field adjusted. To set high
temperature cutout stop,
proceed as follows:
1.
Set dial to temperature at
which stop is desired.
2.
Remove control cover.
Printed in U.S.A.