Siemens ET 141 Owner's manual

Technical Instructions
Document No. 155-021P25
ET 141-5
September 28, 2004
ET 141 High Limit Control
Thermostat
Description The ET 141 high limit control thermostat is duct mounted and has a rigid bulb, bi-metal
rod and tube construction.
Application Normally, the thermostat is used as a high limit control when a "lock-out" type control is
desired or required by local code. Often it is located in a return air duct and is wired to
shut down air conditioning or ventilating fans when the duct air temperature becomes
excessive.
Product Number 141-0530
Specifications Switch Action Single-Pole, Single-Throw (SPST)
manual reset
Scale Range Adjustable from 25°F (-4°C) to
215°F (102°C)
Maximum Bulb Temperature 300°F (149°C)
Cover Finish Gray baked enamel galvanized steel
Shipping Weight 1.8 Ib (0.8 kg)
Thermal System Rigid bulb, bi-metal rod and tube
construction
Dimensions See Figure 3
Agency Certification UL Listed: File MP3487, CCN MBPR
CSA Certified: File LR 948,
Class 4813 02
Table 1. Electrical Ratings.
Locked Rotor
Amps (LRA)
Motor Ratings
(Full Load Amps)
Non-Inductive Amps
120 Vac 240 Vac 120 Vac 240 Vac 120 Vac 240 Vac
96 48 16 8 16 16
Siemens Building Technologies, Inc.

Technical Instructions ET 141 High Limit Control Thermostat
Document Number 155-021P25
September 28, 2004
Operation and
Adjustment The setpoint adjustment knob (see Figure 2) permits adjustment of the setpoint between
25°F and 215°F (-4°C and 101°C).
The temperature differential is factory set, non-adjustable, and approximately 20°F
(11°C), depending on the rate of temperature change.
The standard model includes a knob for setpoint adjustment.
Temperature Setpoint
Stop The temperature setpoint stop is an integral part of these controls, and is field
adjustable. To set the stop, do the following:
1. Set dial temperature at desired stop.
2. Remove control cover.
3. Loosen the stop screw, slide the screw to the front of the control against the plastic
stop behind the dial, and tighten the screw (see Figure 2). Sometimes, an exact stop
setting is not possible, and the stop must be set to the closest stop corresponding to
the required dial setting.
ET0110R1
Cutout Stop Bracket
With Slot and Screw
Setpoint
Adjustment
Screw
Figure 1. Setpoint Stop Screw.
Reset Procedure Verify that the temperature has dropped to 20°F (11°C) below setpoint. Press the reset
lever to reset the unit (closing the circuit).
ET0108R1
Reset Lever
Setpoint Window
Setpoint Knob
Figure 2.
Page 2 Siemens Building Technologies, Inc.

ET 141 High Limit Control Thermostat Technical Instructions
Document Number 155-021P25
September 28, 2004
Installation 1. Select a mounting location for the thermostat in the duct (or plenum). The location
must allow the sensing element to measure the average temperature in the duct.
2. Drill (or cut) a 1-3/8 inch hole in the duct at the selected mounting location (see
Figure 3).
3. Using the flange as a template on the duct, mark the location for two #10 × 1/2" long
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 the two #10 × 1/2" long sheet metal screws
provided.
6. Insert the sensing element and sleeve through the flange installed in Step 5 (and
into the duct).
7. Secure the thermostat to the flange by screwing the set screw firmly against the
sleeve. Do not over-tighten 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 inch
(14 cm) clearance between the sensor and any other objects inside the
duct.
ET0105R1
141-0530
Duct
Set Screw
Flange
Sensing Element
Sleeve
Sheet Metal Screw
Sheet Metal Screw Hole
1-3/8 in. Hole
Figure 3. Installation.
Siemens Building Technologies, Inc. Page 3

Technical Instructions ET 141 High Limit Control Thermostat
Document Number 155-021P25
September 28, 2004
Wiring Diagram 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
ET0106R1
Common
Figure 4. Terminal Identification.
ET0107R1
141-0530
Power Supply Other
Operating or
Limiting Control
Fan Motor
or Motor
Starter Coil
Figure 5. Typical Wiring Diagram.
Checkout
Procedure
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.
Return Air Applications 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.
Page 4 Siemens Building Technologies, Inc.

ET 141 High Limit Control Thermostat Technical Instructions
Document Number 155-021P25
September 28, 2004
Information in this publication is based on current specifications. The company reserves the right to make changes in specifications and models as
design improvements are introduced. Other product or company names mentioned herein may be the trademarks of their respective owners.
© 2004 Siemens Building Technologies, Inc.
Siemens Building Technologies, Inc.
1000 Deerfield Parkway
Your feedback is important to us. If you have
comments about this document, please send
Supply Air Applications 1. After completing the installation and wiring procedures, turn on the power to the
circuit.
2. Raise the supply air temperature to the setpoint temperature.
NOTE: The supply air temperature can be raised by simulating a fan failure or
restricting the return air flow.
3. When the system shuts down, determine the temperature at the thermostat sensing
element. The temperature reading should closely approximate the thermostat's
setpoint at which the system is shut down.
4. Return the system to normal operation by re-establishing the air flow or by restarting
the fan.
5. Press the reset lever. The system should restart.
Service There is no servicing of this thermostat. Replace if inoperative.
Dimensions
ET0109R1
0.25ÿ
(6)
0.75ÿ
(19)
Diameter
Diameter
9.33
(237)
4
(102)
0.5
(13)
0.34
(9)
4.41
(112)
0.35
(9)
1.81
46
1.30
33
1.25
(32)
3.66
(93)
2.16
(55)
0.88
(22) Diameter
0.61
(15)
Figure 6. Dimensions in Inches (Millimeters in Parentheses).
Buffalo Grove, IL 60089-4513
U.S.A.
them to [email protected] Page 5
Document No. 155-021P25
Country of Origin: US