Page 1
POWERS® Controls
Technical Instructions
Document No. A6V11435226
May 9, 2019
134-1861 Humidistat
Siemens Industry, Inc.
Part No 24-8466-00036 Rev. A
Description
The 134-1861 Humidistat controls humidifying and/or dehumidifying equipment. Typical
uses include the control of humidity by ventilation, air conditioning, humidifiers, and
dehumidifiers in residential, commercial, and industrial installations.
This humidistat has Single-Pole/Double-Throw (SPDT) snap-acting contacts rated to
switch 1/4 hp motors. It has a wide setpoint range of 0 to 70% Relative Humidity (RH), as
well as “off” dial positions for humidification and dehumidification. The differential of the
134-1861 is fixed at approximately 6% RH.
Features
• Human Hair Sensing Element – Provides stable, accurate measurement.
• 1/4 HP (6A) Rated Contacts – Permit direct operation of many fans in commercial
applications.
• High/low Adjustable Knob Range Stops – Allow adjustments within a desired range.
• Enclosed Pennswitch – Provides dust protection for contacts.
• Mounting Plate – Allows easy mounting and wiring without removing the cover.
Product Number 134-1861
Accessories Concealed Adjustment Faceplate, Vertical Mounting 134-034
Aluminum Guard 134-117
Warning/Caution Notations
WARNING:
Personal injury or loss of life may occur if a procedure is not
performed as specified.
CAUTION:
Equipment damage or loss of data may occur if the user
does not follow a procedure as specified
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Technical Instructions POWERS Controls 134-1861 Humidistat
Document Number A6V11435226
May 9, 2019
Page 2 Siemens Industry, Inc.
Introduction
The 134-1861 Humidistat provides SPDT control for use on low or line voltage
applications. It has a thermoplastic cover with an Allen-head locking screw to discourage
unauthorized tampering. The sensing element consists of carefully selected and
processed human hair.
An adjusting knob and easy-to-read dial allow quick selection of the desired setpoint. The
humidistat is supplied with the faceplate installed for vertical mounting and knob
adjustment. However, a horizontal faceplate is enclosed for horizontal mounting and
knob adjustment if desired. There is also an optional Concealed Adjustment Faceplate
(P/N 134-034) available for installations where humidity adjustment by the occupants is
not desired.
WARNING:
The low temperature detection thermostat is designed for use only as an
operating control. Where an operating control failure would result in
personal injury and/or loss of property, it is the responsibility of the
installer to add devices (safety, limit controls) or systems (alarm,
supervisory systems) that protect against, or warn of control failure.
Operation
The humidistat has a setpoint range of 0 to 70% RH, as well as humidification off (HUM
OFF) and dehumidification off (DEH OFF) positions. At the HUM OFF position, the C to L
terminal circuit is open and the C to H terminal circuit is closed. At the DEH OFF position,
the C to H terminal circuit is open and the C to L terminal controls the humidification
equipment.
At any given setpoint, the C to L circuit closes on a decrease in relative humidity, and the
C to H circuit closes on an increase in relative humidity.
The usual setting in winter is 30 to 40% RH. Lower settings may be necessary in
extremely cold weather to prevent condensation on windows, doors, and so on. The
same setting should be used where reduction of humidity by means of exhaust fans is
provided in well-constructed homes. Summer settings on air conditioning or
dehumidifying equipment will usually be near 50% RH.
The suggested indoor humidity at 70F (21C) for residential applications on humidifying
or dehumidifying equipment in winter is shown in Table 1.
Table 1. Humidity Settings.
Outside Temperature
Suggested Humidity Setting
-20F (-29C) and Below
15% RH
-10F (-23C)
20% RH
0F (-18C)
25% RH
10F (-12C)
30% RH
20F (-7C)
35% RH
Above 20F (-7C)
40% RH or Higher as Desired
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POWERS Controls 134-1861 Humidistat Technical Instructions
Document Number A6V11435226
May 9, 2019
Siemens Industry, Inc. Page 3
Specifications
Contact ratings 120 Vac 208 Vac 240 Vac
Full load ampere 6.0 3.5 3.0
Locked rotor ampere 36.0 21.0 18.0
Pilot duty 125 VA at 24/277 Vac
Switch action SPDT
Switch Snap-acting in a dust-protected
enclosure
Range 0 to 70% RH
Ambient temperature 40 to 100°F (4.4 to 38°C)
Differential Fixed at approximately 6% RH
Sensing element Selected human hair
Material
Case 0.050 inch (1.27 mm) cold rolled steel
Cover Beige thermoplastic
Finish
Base Zinc plate dichromate dipped
Cover Brown markings on gold anodized
aluminum
Mounting Vertical or horizontal 2 × 4 in.
(51 × 102 mm) wall box
Wiring terminals Large 8-32 × 1/4 in. binder head screws
Weight 0.9 lb. (0.4 kg)
Dimensions 4.71 × 2.96 × 2.94 in.
(120 × 75 × 75 mm)
Agency listings UL Guide No. XAPX; File E6688
CSA Class No. 4813.02 File LR948
Mounting and
Installation
General Guidelines
Locate the 134-1861 as follows:
• on an inside wall away from ranges, sinks, bathrooms, or other areas of extreme
moisture and temperature.
• where natural air circulation is unrestricted.
• where lamps, sunlight, fireplaces, heat registers, radiators, concealed air ducts or
pipes, or room occupants will not affect its operation.
Required Tools
• 2 × 4 in. (51 × 102 mm) wall box (field-supplied)
• 3-wire cable (field supplied)
• Screwdriver (slotted standard)
• Marking pencil
• Wire strippers
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Technical Instructions POWERS Controls 134-1861 Humidistat
Document Number A6V11435226
May 9, 2019
Page 4 Siemens Industry, Inc.
Installation
CAUTION:
Do not remove the humidistat cover during installation. The sensing
element must be carefully protected against accidental damage. All wiring
and mounting can be completed without removing the cover.
WARNING:
Shock hazard. Disconnect the power supply before wiring connections are
made to prevent electrical shock or possible damage to the equipment.
1. Select the proper mounting location (see General Guidelines) and install a
vertical or horizontal wall box 4 to 5 feet (1.2 to 1.5 m) above the floor.
2. Run conduit or cable, as required by national and/or local electric codes, from
the wall box to the equipment to be controlled. Leave approximately 6 inches
(152 mm) of wire for connection to the humidistat terminals.
3. Remove the humidistat mounting plate by loosening the mounting plate locking
screw (see Figure 1) and lifting and removing the plate from the base.
4. Pull wires through the mounting plate and fasten the plate, grounding screw end
up, to the wall box with the screws provided.
5. Strip the wires and connect to the proper terminals on the back of the humidistat.
See Wiring Diagrams.
NOTE: Use the terminal screws provided (8-32 × 1/4 in. binder head).
Substitution of other screws may cause problems in making proper connections.
6. Connect the grounding provision of the humidistat to the branch circuit ground.
7. Hook the two slots in the humidistat base over the projections on the mounting
plate and swing the humidistat into place. Push the wires back flush into the wall
box.
8. Securely tighten the mounting plate locking screw.
The installation is now complete.
Figure 1. 134-1861 Humidistat.
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POWERS Controls 134-1861 Humidistat Technical Instructions
Document Number A6V11435226
May 9, 2019
Siemens Industry, Inc. Page 5
Mounting and
Installation,
continued
(Optional) Horizontal
Faceplate Installation
1. Mount and wire the humidistat. See Installation.
2. Pull the adjustment knob off the humidistat cover.
3. Peel off the backing of the horizontal faceplate.
4. Position the horizontal faceplate over the factory-installed vertical faceplate. Ensure
that the plate is positioned straight and even to over the existing plate.
5. Firmly press the horizontal faceplate onto the humidistat cover.
6. Replace the adjustment knob.
The installation is now complete.
Wiring Diagrams
Figure 2. Typical Wiring Diagram of a 134-1861 Used to Reduce Excessive
Humidity in a Well-Constructed Building by Manual or Automatic Control of an
Exhaust Fan.
Figure 3. Dehumidification Control Wiring Diagram.
Figure 4. Humidification Control Wiring Diagram.
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Technical Instructions POWERS Controls 134-1861 Humidistat
Document Number A6V11435226
May 9, 2019
Page 6 Siemens Industry, Inc.
Figure 5. Schematic Wiring Diagram of a 134-1861 Automatically Operating a
Humidifier or Dehumidifier as Selected by the Manual Changeover Switch.
Figure 6. Schematic Wiring Diagram of a 134-1861 Automatically Operating an
Exhaust Fan at Full Speed to Control Excessive Humidity. A Combination Speed
Control and “On/Off” Switch Permits Manual Operation of an Exhaust Fan at
Selected Speeds.
Range Stops
High and low range stops of the humidistat can be field adjusted as desired. Use the
following procedures to set the high and low range stops.
High Range Stop
1. Set the adjustment knob to the maximum desired RH setting.
2. Pull the adjustment knob off the humidistat cover.
3. Loosen the bottom cover screw and remove the humidistat cover.
CAUTION:
Equipment damage hazard.
Avoid contact with the human hair sensing element. Contact
with the hair element can affect control accuracy and/or
product life.
4. While holding the dial firmly in place, keep the setting in line with the calibrating
mark, press Tab A (see Figure 7) and rotate it counterclockwise until it is
against Stop Pin C.
5. Release the tab making sure it fits into the nearest notch.
6. Replace the humidistat cover, tighten the bottom cover screw, and replace the
adjustment knob.
7. Rotate adjustment knob to desired normal operating setpoint.
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POWERS Controls 134-1861 Humidistat Technical Instructions
Document Number A6V11435226
May 9, 2019
Siemens Industry, Inc. Page 7
Low Range Stop
1. Set the adjustment knob to the minimum desired RH setting.
2. Pull the adjustment knob off the humidistat cover.
3. Loosen the bottom cover screw and remove the humidistat cover.
CAUTION:
Equipment damage hazard.
Avoid contact with the human hair sensing element. Contact
with the hair element can affect control accuracy and/or
product life.
4. While holding the dial firmly in place, keep the setting in line with the calibrating
mark, press Tab B (see Figure 7) and rotate it clockwise until it is against the
stop pin C.
5. Release the tab making sure it fits into the nearest notch.
6. Replace the humidistat cover, tighten the bottom cover screw, and replace the
adjustment knob.
7. Rotate adjustment knob to desired normal operating setpoint.
Figure 7. 134-1861 Humidistat Range Tabs and Stop
Dial Lock
The high and low range stops can be set to keep the adjustment knob from rotating. To
lock the dial:
1. Set the adjustment knob to the minimum desired RH setting.
2. Pull the adjustment knob off the humidistat cover.
3. Loosen the bottom cover screw and remove the humidistat cover.
CAUTION:
Equipment damage hazard.
Avoid contact with the human hair sensing element. Contact
with the hair element can affect control accuracy and/or
product life.
Page 8
Technical Instructions POWERS Controls 134-1861 Humidistat
Document Number A6V11435226
May 9, 2019
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. POWERS is a registered trademark of Siemens Industry, Inc. Other product or company names mentioned
herein may be the trademarks of their respective owners. © 2019 Siemens Industry, Inc.
Siemens Industry, Inc.
Smart Infrastructure
1000 Deerfield Parkway
Buffalo Grove, IL 60089
+ 1 847-215-1000
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this document, please send them to
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Document No. A6V11435226
Printed in the USA
Page 8
Dial Lock, Continued
4. While holding the dial firmly in place, keep the setting in line with the calibrating
mark, press Tab A and rotate it counterclockwise until it is against Stop Pin C.
Press Tab B and rotate it clockwise until it is against Stop Pin C. See Figure 7.
5. Ensure each tab fits into the notch closest to the stop.
6. Replace the humidistat cover, tighten the bottom cover screw, and replace the
adjustment knob.
Checkout Procedure
Before applying power, ensure that installation and wiring connections are made
according to job specifications.
After all necessary adjustments and electrical connections have been made, put the
system into operation and observe at least three complete operating cycles before
leaving the installation.
Service
There is no servicing of the humidistat. For a replacement 134-1861, contact your local
Siemens Industry representative.
Dimensions
Figure 8. Dimensions of the 134-1861 Humidistat in Inches (Millimeters).
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