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Technical Instructions
Document Number 155-021P25
September 28, 2004
Wiring Diagram
Checkout
Procedure
Return Air Applications
Page 4
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.
See Figures 4 and 5 for terminal identification and typical wiring connections.
NOTE:
Only use the terminal screws furnished with the thermostat (#8-32 ×
1/4-inch binder head). Use of other screws will void warranty, may damage
switch terminals, and result in improper connections
Common
Figure 4. Terminal Identification.
After installing the thermostat, perform the following procedures. Observe at least three
complete operating cycles to verify that all components are functioning properly. If the
unit fails to checkout, replace it.
1. After completing the installation and wiring procedures, turn on the power to the
circuit.
2. Turn the setpoint knob counterclockwise until the thermostat shuts down the system.
The thermostat should lock-out.
NOTE:
The setpoint at shutdown should equal the approximate duct air
temperature.
3. Turn the setpoint knob clockwise to the desired setpoint. Nothing should happen.
4. Press the reset lever. The system should restart.
ET 141 High Limit Control Thermostat
Power Supply
Operating or
141-0530
Limiting Control
Figure 5. Typical Wiring Diagram.
Siemens Building Technologies, Inc.
Fan Motor
Other
or Motor
Starter Coil
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