Johnson Controls A28 Series Data Sheet
Action on Increase
of Temperature
Y
B
R
Y
B
R
A28 Series
Low Stage
High Stage
A28 Action Diagram
a28.eps
A28AA-4
Temperature
Control
A28AB-29
Temperature
Control
Multi-Stage Electromechanical Temperature Controls
A28 Series Two-Stage Temperature Control
Description
The A28 Series are two-stage temperature controls that incorporate a
liquid-filled sensing element.
Refer to the A28 Series Two-Stage Temperature Controls with
NEMA 1 Enclosure Product Bulletin Product Bulletin (LIT-125130) for
important product application information.
Features
• wide temperature ranges available
• constant differential throughout the entire range
• single-pole, double-throw (SPDT) snap-acting switches
• unaffected by changes in barometric pressure
• unaffected by cross ambient conditions
• compact enclosure
• variety of sensing element styles
Code No. LIT-1927110
Applications
Use for temperature sensing applications requiring two-stage control of
HVAC/R equipment.
Accessories
• packing nut assembly available for direct immersion applications
(Code No. FTG13A-600R)
• remote bulb models include 5/8 in. mounting clip
Selection Charts
Product Code
Number
A28AA-4C Two-SPDT 30 to 110
A28AA-9C Two-SPDT 20 to 80
A28AA-28C Two-SPDT 30 to 110
A28AA-29C Two-SPDT -30 to 100
A28AA-36C Two-SPDT 40 to 90
A28AA-37C Two-SPDT 60 to 140
A28AJ-4C Two-SPDT 20 to 80
A28AB-1C Two-SPDT
1. Packing nut assembly available for direct immersion applications (Code No. FTG13A-600R).
2. Switches within 1 F° (0.6 C°) of each other.
The performance specifications are nomina l and con form to accep table ind ustry stand ards. For applicati ons at con ditions be yond these specification s, consult th
Johnson Controls, Inc. shall not be liable for damages resulting from misapplication or misuse of its products. © 2015 Johnson Controls, Inc.
Switch
Action
Range
°F (°C)
Differential
F° (C°)
Bulb and
Capillary
Bulb Well No.
(Order Separately)
Range
Adjuster
Coiled Bulb-Fixed Differential
(-1 to 43)
3-1/2 (1.9) each stage
3 (1.7) fixed between stages
1-3/8 in. x 2-1/4 in.
coiled
–Convertible
Case Compensated-Fixed Differential
(-7 to 27)
3-1/2 (1.9) each stage
3 (1.7) fixed between stages
3/8 in. x 5 in.
6 ft capillary
1
WEL14A-603R Knob
Wide Range-Adjustable Interstage Differential
(-1 to 43)
(-34 to 38)
(4 to 32)
(16 to 60)
(-7 to 27)
3-1/2 (1.9) each stage
2 to 7 adjustable between stages
5 (2.8) each stage
2 to 7 adjustable between stages
3 each stage
2 to 7 adjustable between stages
5 each stage
2 to 7 adjustable between stages
2 each stage
2 to 7 adjustable between stages
12 ft averaging bulb
6 ft capillary
3/8 in. x 4 in.
8 ft capillary
3/8 in. x 5-3/4 in.
6 ft capillary
3/8 in. x 4 in.
6 ft capillary
3/16 in. x 22 in.
6 ft capillary
1
– Screwdriver
slot
WEL14A-602R Convertible
– Knob
WEL14A-602R Knob
– Knob
Changeover Control
2
20 to 80
(-7 to 27)
3-1/2
(1.9)
R-59
3/8 in. x 5 in.
6 ft capillary
WEL14A-603R Screwdriver
slot
Multi-Stage Electromechanical Temperature Controls
A28 Series Two-Stage Temperature Control (Continued)
Replacement Parts
Product Code Number Description
CVR28A-617R Concealed adjustment
CVR28A-618R Visible scale
KNB20A-602R Knob kit
Technical Specifications
Maximum bulb temperature of A28AA-37 is 230°F (110°C). For all others, maximum bulb temperature is 140°F (60°C).
Electrical Ratings
Motor Ratings VAC 120 208 240 277
A28AA, A
AC Full Load A 16.0 9.2 8.0 ---
AC Locked Rotor A 96.0 55.2 48.0 ---
Non-Inductive or Resistance Load A
(Not Lamp Loads)
Pilot Duty 125 VA, 24 to 277 VAC
AC Full Load A 6.0 3.4 3.0 ---
AC Locked Rotor A 36.0 20.4 18.0 ---
Non-Inductive or Resistance Load A
(Not Lamp Loads)
Pilot Duty 125 VA, 24 to 277 VAC
AC Full Load A 16.0 9.2 8.0 ---
AC Locked Rotor A 96.0 55.2 48.0 ---
Non-Inductive or Resistance Load A
(Not Lamp Loads)
Pilot Duty 125 VA, 24 to 277 VAC
1. When used as two-circuit control, the total connected load must not exceed 2,000 VA.
16.0 9.2 8.0 7.2
1
A28AJ
15.0 9.2 8.0 7.2
1
A28AB
16.0 9.2 8.0 7.2
1
The performance specifications are no minal and co nform t o acceptab le ind ustry standar ds. For appl ications at condition s beyond these specifica tions, consult th
Johnson Controls, Inc. shall not be liable for damages resulting from misapplication or misuse of its products. © 2015 Johnson Controls, Inc.
R-60
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