CaptiveAire A25AN User Manual

A25 Series Warm Air Control with Manual Reset

The A25 Series Warm Air Control with Manual Reset is
designed to shut down fans, burners, dampers, etc.,
when the temperature of the sensed air becomes
greater than the controller’s setpoint.

When the sensed temperature increases to the
controller’s setpoint, the A25’s switch will open.
Manual reset is required to reclose the electrical circuit.
The A25 may be used as a high limit control in the
supply air duct (or plenum) where a lockout type
control is desired or required by local code.

FANs 125, 121

Product/Technical Bulletin A25

Issue Date 0796

Figure 1: The A25 Series Warm Air Control

with Manual Reset

Features and Benefits

❑

Trip-free Reset Lever Does not allow the reset switch to hold the contacts in a closed (on)

position

❑

Pilot Duty Electrical Rating for
up to 600 Volts Maximum

❑

Enclosed Switch Protects switch contacts from dust

❑

Rod and Tube Sensing
Element

❑

Adjustable Duct
Mounting Flange

❑

Wide Temperature Range Allows the A25 to be used with many applications

Allows direct control of high voltage motor starters

Provides maximum response and allows for a high maximum
sensing element temperature

Controls the depth of sensor insertion into the airstream;
compensates for insulation depth

© 1996 Johnson Controls, Inc.

Part 24-7664-656, Rev.—
Code No. LIT-125118

1

pplication Overview

A

A typical application for the A25 Series Warm Air
Control with Manual Reset is to stop the operation of
air conditioning or ventilating fans upon a temperature
rise. Models A25AP and A25CP are Factory Mutual
approved for use as fire protection devices.

3. Using the flange as a template on the duct, mark
the location for two 1/2 in. (13 mm) No. 10 sheet
metal screws.

4. Punch (or drill) both sheet metal screw holes in the
duct at the marked locations.

5. Secure the flange to the duct with two 1/2 in.
(13 mm) No. 10 sheet metal screws provided.

nstallation

I

1. Select a mounting location for the A25 in the duct
(or plenum). The location must allow the sensing
element to sense the average temperature in the
duct.

2. Drill (or cut) a 1-3/8 in. hole in the duct at the
selected mounting location (refer to Figure 2).

6. Insert the sensing element and sleeve through the
flange installed in Step 5 (and into the duct).

7. Secure the A25 to the flange by screwing the set
screw firmly against the sleeve. Do not
overtorque the set screw.

Note: Insert the sensing element as far as possible

into the air stream without allowing it to contact
any object inside the duct. Provide at least
5-3/4 in. (14 cm) clearance between the
sensor and any other objects inside the duct.

Figure 2: Installing the A25

2 A25 Series Warm Air Control with Manual Reset Product/Technical Bulletin

iring

W

WARNING: Shock hazard. To avoid

electrical shock or damage to
equipment, disconnect all power
before making wiring
connections.

If available, follow the instructions for the unit onto
which the A25 will be installed. Make all wiring
connections only with copper conductors and in
accordance with the National Electrical Code and local
regulations. Refer to the label inside the A25’s cover
for the maximum electrical rating.

Models A25CN and A25CP
SPDT (Single Pole Double Throw) Units

The wiring terminals on the SPDT (Single Pole
Double Throw) models are color coded:

●

Red is common.

●

The red to yellow circuit closes on temperature
increase.

Figure 3: Terminal Identification for

A25CN and A25CP SPDT Models

Figure 4: Typical Wiring Diagram of

A25CN and A25CP SPDT Models

●

The red to blue circuit opens on temperature
increase.

Refer to Figures 3 and 4 for terminal identification and
typical wiring connections.

When the reset lever is pressed during normal
operation, the trip free contacts are activated, the red
to blue contact opens and the auxiliary red to yellow
contact closes. At this point, the auxiliary system
will activate.

Models A25AN and A25AP
SPST (Single Pole Single Throw) Units

When the temperature increases to above the setpoint,
the circuit opens. When the reset lever is pressed after
the sensed temperature decreases to approximately
20F° (11C°) below the setpoint, the circuit closes.

Refer to Figures 5 and 6 for terminal identification and
typical wiring connections.

IMPORTANT: Only use the terminal screws

furnished with the A25 (8-32 x
1/4 in. binder head). Use of other
screws will void warranty, may
damage switch terminals, and
result in improper connections.

Figure 5: Terminal Identification for

A25AN and A25AP SPST Models

Figure 6: Typical Wiring Diagram for

A25AN and A25AP SPST Models

A25 Series Warm Air Control with Manual Reset Product/Technical Bulletin 3