Johnson Controls T25 User manual

Installation Instructions T25
Issue Date 02/15/02
© 2002 Johnson Controls, Inc. 1
Part No. 24-9716-5, Rev. A www.johnsoncontrols.com
T25 Two-Stage Room Thermostat
Application Requirements
T25 thermostats are for line- or low-voltage service
requiring accurate control of two operating functions.
There are two stages of control for heating and
cooling with automatic changeover on three- and
four-pipe fan coil installations and similar
applications. Typical uses are for compressor
controls, relays, valves, fan coils, and other
applications where low differentials and accurate
sensing are required.
Installation
IMPORTANT: The T25 Series Thermostats are
intended to control equipment under normal
operating conditions. Where failure or malfunction
of the T25 Thermostats could lead to an abnormal
operating condition that could cause personal
injury or damage to the equipment or other
property, other devices (limit or safety controls) or
systems (alarm or supervisory systems) intended
to warn of, or protect against, failure or malfunction
of the T25 Thermostats must be incorporated into
and maintained as part of the control system.
Parts Included
•1 thermostat
•1 Allen wrench
•2 machine screws
Dimensions
Refer to Figure 1 for detailed dimensions of the T25
Two-Stage room Thermostat.
Mounting
Location Considerations
Mount the thermostat about 4 to 5 ft. (1.2 to 1.5 m)
above the floor on an interior wall, where it can sense
the average room temperature. It is designed for vertical
mounting and will produce the lowest operating
differentials when installed in this position.
Do not mount the thermostat where it may react to heat
or cold from water pipes, windows, doors, lamps,
sunlight, or other heat or cold sources.
On unit heater applications, place the thermostat below
and behind the heater in the path of air entering the unit,
not in the path of discharge air.
2.78
(71)
1.13
(29)
5.22
(133)
0.63
(16)
Diameter
1.06
(27)
1.94
(49)
1.88
(48)
0.41
(10) Two Threaded
Studs
3.28
(83)
0.63
(16)
Two Mounting Holes
0.28
(7.1)
0.15
(3.8)
x
2.84
(72)
1.44
(37)
Figure 1: T25A Dimensions, in. (mm)

2 T25 Two-Stage Room Thermostat Installation Instructions
Mounting
Plate
Studs
High
Temperature
Stop
Set Point
Knob
Figure 2: Inside View of T25
Wall Box Mounting
To mount the thermostat to an electrical conduit box,
proceed as follows:
1. Remove the external adjustment knob, when
furnished, by loosening the knob set screw using
the provided Allen wrench. Slide the knob from the
adjustment shaft.
2. Remove the cover by loosening the Allen-head
screws at the top and bottom of the thermostat.
3. Remove the adaptor plate from the back of the
thermostat by loosening the machine nuts (inside
the thermostat) from the two threaded studs on the
plate.
!
WARNING: Risk of Electrical Shock.
Electrical thermostat wires may be energized at
line-voltage potential. Disconnect the electrical
power supply before pulling wires to avoid possible
electrical shock or equipment damage. More than
one disconnect may be required to de-energize
control.
4. Pull the electrical thermostat wires through the
opening in the thermostat adaptor plate.
5. Secure the adaptor plate to the conduit box with
the two machine screws provided.
6. Insert the wires through the opening in the
thermostat base.
7. Place the thermostat on the adaptor plate, so that
the two threaded studs on the adaptor plate pass
through the corresponding holes in the thermostat
base (upper left and lower right corners).
8. Secure the thermostat to the adaptor plate with the
two machine nuts referred to in Step 3.
9. Refer to the Wiring section to connect the
terminals on the Pennswitches.
10. If a high temperature stop is desired, proceed to
the Setup and Adjustments section.
Wall Surface Mounting
To mount the thermostat directly to an interior wall
surface (no electrical box) proceed as follows:
1. At the desired thermostat location, make an
opening in the wall approximately 1/2 in. in
diameter, and pull the wires through it.
2. Plug the rest of the wall opening to prevent drafts
from affecting the operation of the thermostat
(when applicable).
3. Remove the adjusting knob, thermostat cover, and
adaptor plate. See Steps 1, 2, and 3 under
Wall Box Mounting.
4. Pull the electrical thermostat wires through the
opening in the thermostat adaptor plate.
5. Secure the adaptor plate to the mounting surface.
Note: When mounting on uneven surfaces, always
use the adaptor plate in order to prevent twisting the
unit and consequently affecting thermostat calibration
and operation.
6. Proceed as outlined in Step 6 through Step 10 in
the Wall Box Mounting section.
Wiring
Make all wiring connections using copper conductors
only in accordance with the National Electrical Code
and local regulations. Use a relay or motor starter to
handle loads that exceed the rating of the thermostat.
!
WARNING: Risk of Electrical Shock.
Disconnect the electrical power supply before
making the wiring connections to avoid possible
electrical shock or equipment damage. On multiple
circuit units, more than one circuit may have to be
disconnected.
For low-voltage applications, use 18 AWG wire or
larger for all connections to the thermostat. Use
14 AWG wire on runs over 500 ft. Make all splices in
junction boxes using approved solderless connectors,
or by soldering and then taping the connection.

T25 Two-Stage Room Thermostat Installation Instructions 3
Make all wiring connections to the screw terminals on
the Pennswitches.
•Use the terminal screws supplied with the
Pennswitches. Screws longer than 1/4 in. can
cause problems in making proper connections.
•Connect the thermostat grounding provision to the
grounding conductor of the branch circuit.
Refer to Figure 4, Figure 5, Figure 6, Figure 7, and
Figure 8 for typical wiring diagrams.
Note: Use the furnished terminal screws
(8-32 by 1/4 in. binder head). Substitution of other
screws may cause problems in making proper
connections.
LL
LO -Temp
Stage
Y
B
h
R
HI-Temp
Stage
Y
B
h
R
Temperature
Dial
Temperature
Fall
H
H
RY Opens
L
RB Closes
Low
Stage
D
Temperature
Rise Dial
Settings
RY Closes
RB Opens
H
RY Closes
L
RB Opens
D
High
Stage
Note: RB , RY indicates
HI-TEMP. RB , RY indicates
LO-TEMP. D represents differential
between stages. H represents High.
L represents Low.
H
H
H
Figure 3: Two-stage Control Switching Action
Hot
Hot
or
Neutral
Power Supply
Cooling
Equipment
Heating
Equipment
Hot (240 VAC)
or Neutral (120 VAC)
YHYL
BHBL
RHRL
Figure 4: Typical Wiring for One-stage Heating and
One-stage Cooling
Hot
Hot
or
Neutral
Power Supply
2nd Stage
Cooling
Hot (240 VAC)
or Neutral (120 VAC) 1st Stage
Cooling
YHYL
BHBL
RHRL
Figure 5: Typical Wiring for Two-stage Cooling
Hot
Hot
or
Neutral
Power Supply
To
1st Stage
Heating
To
2nd Stage
Heating
Hot (240 VAC)
or Neutral (120 VAC)
YHYL
BHBL
RHRL
Figure 6: Typical Wiring for Two-stage Heating
Hot
Hot
or
Neutral
Power Supply
Heating
Valve
Hot (240 VAC)
or Neutral (120 VAC) Cooling
Valve
Fan
HI-Temp LO -Temp
YHY
L
BHBL
RHRL
Note: The application is wired for simultaneous cycling of
valve and fan. Cooling will operate at a higher
temperature than heating even though connections
are to opposite stages.
Figure 7: Typical Wiring for Fully Automatic
Heating and Cooling Service

4 T25 Two-Stage Room Thermostat Installation Instructions
Hot
Hot
or
Neutral
Power Supply
Reversing
Valve
Hot (240 VAC) or
Neutral (120 VAC)
Compressor
Fan
Y
HY
L
B
HBL
RHRL
Figure 8: Typical Heat Pump Wiring for
Combination Heating and Cooling, Continuous Fan
Setup and Adjustments
The indicator line on models with knobs denotes the
thermostat dial setting. Concealed adjustment models
have internal adjustment dials. Adjust concealed dial
models (with the cover removed) by turning the dial
and lining up the desired dial setting at a 9 o’clock
position when the thermostat is vertical.
Calibration
The T25 thermostats are factory calibrated. Do not
attempt field calibration.
Set Screw
High
Temperature
Stop
Set Point Knob
Figure 9: Setting the High Temperature Stop
Commissioning the High Temperature Stop
If a high temperature stop is desired, refer to Figure 9
and follow the procedure described below.
1. Turn the thermostat dial so that the desired
setting, minus one degree, is in line with the slot in
the high temperature slot bracket, as shown in
Figure 9. For example, to set the stop at 76°F
(24°C), line up the 75°F (23°C) mark on the
temperature dial with the slot.
2. Loosen the stop screw and slide the screw toward
the back of the dial (the front of the unit) against
the step behind the dial.
3. Tighten the stop screw.
Note: For concealed adjustment models, set the
desired temperature and switch functions before
replacing the cover.
Checkout
Before completing the installation, observe at least
three complete operating cycles to ensure that all
components are functioning correctly.
Heating
If the unit has a system selector, select the Heating or
Auto position. Turn the set point knob to a temperature
well above room temperature. This simulates a
temperature fall and should cycle on the heating
system. Turn the set point knob about 10F° (5.6C°)
below the room temperature. The heating system
should stop. Turn the knob to the desired setting.
Cooling
If the unit has a system selector, select the Cooling or
Auto position. Turn the set point knob to a temperature
well below the room temperature. This simulates a
temperature rise and should cycle on the cooling
system. Turn the set point knob about 10F° (5.6C°)
above the room temperature. The cooling system
should stop. Turn the knob to the desired setting.
Repairs and Replacement
Do not make field repairs. To replace the thermostat,
cover, knobs, or faceplate contact the nearest
Johnson Controls representative.

T25 Two-Stage Room Thermostat Installation Instructions 5
Table 1: Electrical Ratings
Motor Ratings 120 V 208 V 240 V 277 V
AC Full Load Amperes 6.0 3.5 3.0 -
AC Locked Rotor Amperes 36.0 21.0 18.0 -
Non-inductive Amperes 10.0 9.2 8.0 7.2
Pilot Duty—125 VA 24 to 277 VAC
Note: When used as a two-circuit switch, the total connected load must not exceed 2,000 VA.
Technical Data
Product T25 Two-Stage Room Thermostat
Output Single Pole, Double Throw (SPDT)
Switches Two Enclosed Pennswitches
Cover Cold Rolled Steel with “Tawny Silver” Finish
Each Stage 0.7F° (0.4C°) ApproximatelyDifferential (Mechanical)
Between Stages 3F° (1.7C°) Non-Adjustable
Supply Voltage 24 V, 120 V, 208 V, 240 V, 277 V
Mounting With Adaptor Plate for Wall or Electrical Box Mounting; Vertical
Mounting Only
Thermostat 40 to 90°F (5 to 32°C)Range
Thermometer 50 to 90°F (10 to 32°C)
Sensing Element Liquid Charged, No Leveling Required
Individual Pack 1.5 lbs (0.7 kg)Shipping Weight
Overpack of
20 Units
32 lbs (14.5 kg)
Terminals Screw Type. Color Coded:
Red is Common.
Red Closes to Yellow on Temperature Rise.
Red Closes to Blue on Temperature Drop.
Thermometer Bimetal
Agency Listings UL Listed; File E6688, CCN XAPX (U.S.), CCN XAPX7 (Canada)
CSA Certified; File LR948, Class 4813 02
The performance specifications are nominal and conform to acceptable industry standards. For application at conditions beyond these
specifications, consult the local Johnson Controls office. Johnson Controls, Inc. shall not be liable for damages resulting from misapplication or
misuse of its products.
Controls Group
507 E. Michigan Street
P.O. Box 423 Printed in U.S.A.
Milwaukee, WI 53201 www.johnsoncontrols.com