Humidistats

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Humidistats

Instruments, sensors and controls

Humidistats are used for reliable monitoring and control of relative humidity in duct and room applications across industrial, commercial and residential environments. They are typically applied where simple and dependable On/Off humidity control is sufficient, or where humidity limits must be supervised as part of a system safety loop.

Depending on the application, humidistats can be used to control humidification or dehumidification processes, or to act as high-limit devices that protect installations and building structures from excessive humidity levels. Typical use cases include storage areas, production facilities, technical rooms and process-related environments with defined humidity requirements.

The product group includes both electronic humidistats with display and mechanical humidistats without power supply. Electronic versions provide clear visual indication of humidity values and allow password-protected adjustment of user and control parameters, while mechanical models offer robust, maintenance-free operation in demanding conditions.

Humidistats are available for duct and room installation, with various mounting options and housing designs to suit different installation requirements. Capacitive sensing elements and proven mechanical measuring principles ensure stable and accurate humidity measurement over a wide operating range.

Humidistats

Top of page CHD MD - max. hygro CHR MHD MHR FAQs

CHD – Duct Humidistat with Display

Duct Humidistat with Display

Designed for industrial and commercial duct applications, this humidistat is intended for installations where simple On/Off humidity control is sufficient, such as in the woodwork industry or storage halls. It can also be used as a high-limit humidistat within the system safety loop when a display is required.

The unit provides binary control for humidifiers and features password-protected user and control parameters to ensure secure operation. A backlit display allows clear visibility of operating values, while a capacitive sensing element ensures reliable and accurate humidity measurement.

Technical details

Accuracy: ±4.5 % rH
Supply: 24 V AC/DC
Output: 1x dry contact
Probe length: 157 mm (6.2")

Product overview

Maximum Hygrostat MD – Duct Humidistat with Display (CHD-S) incl. cable

Duct Humidistat with Display (CHD-S) incl. cable

Designed for private end-user duct applications, this humidistat is used as a high-limit device and is intended to be wired into the system safety loop where a humidistat with display is required. It provides reliable binary control for humidifiers, ensuring safe and straightforward humidity supervision.

The humidistat features password-protected user and control parameters for secure adjustment, a backlit display for clear readability, and a capacitive sensing element that delivers stable and accurate humidity measurement.

Technical details

Accuracy: ±4.5 % rH
Supply: 24 V AC/DC
Output: dry contact
Probe length: 76 mm (3")

Product overview

CHR – Room Humidistat with display

Room Humidistat with display

Designed for industrial and commercial room applications, this humidistat is suitable for installations where simple On/Off humidity control is sufficient, such as in woodwork industries or storage halls. It can be applied with RS/EL systems featuring a blower pack or with direct room devices, and may also be used as a high-limit humidistat within the system safety loop when a display is required.

The unit is housed in an EU-standard flush-mount enclosure compatible with 68 mm and 71 mm mounting boxes, enabling easy integration into building installations. It provides binary control for humidifiers and features password-protected user and control parameters for secure operation. A backlit display ensures clear readability, while a capacitive sensing element delivers reliable and accurate humidity measurement. A surface-mounted connection box is included to support flexible installation.

Technical details

Accuracy: ±4.5 % rH
Supply: 24 V AC/DC
Output: 2x dry contact

Product overview

MHD – Mechanical Duct Humidistat

Mechanical Duct Humidistat

Designed for industrial and commercial duct applications, this limiting humidistat is intended to be wired into the system safety loop to provide reliable humidity supervision. It is suitable for use in both humidification and dehumidification systems and is designed to operate reliably even at high humidity levels.

The humidistat features a robust design with an IP65 rating, ensuring protection in demanding environments. It supports a switching load of up to 15 A at 250 V and is supplied with a mounting flange and wall holder to facilitate flexible and secure installation.

Technical details

Accuracy: ±4.5 % rH
Range: 35…95 % rH
Output: changeover contact
No power supply needed

Product overview

MHR - Mechanical Room Humidistat

Mechanical Room Humidistat

This limiting humidistat is suitable for use in both duct and room applications and is intended to be wired into the system safety loop for reliable humidity supervision. It can be used in both humidification and dehumidification systems and is designed to operate reliably even at high humidity levels.

The humidistat supports a switching load of up to 15 A at 250 V and features an IP30-rated enclosure, making it suitable for a wide range of installation environments.

Technical details

Accuracy: ±3 % rH
Range: 25…95 % rH
Output: changeover contact
No power supply needed

Product overview

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Frequently asked questions

How do humidistats improve energy efficiency in HVAC systems?

By activating humidification only when humidity falls below the setpoint, a humidistat prevents unnecessary operation. This reduces water and energy consumption while limiting wear on equipment.

In heating seasons, controlled humidity levels can also improve perceived comfort, potentially allowing for lower room temperatures without sacrificing wellbeing. This contributes to overall HVAC efficiency and operational cost savings.

What is a humidistat and how does it work?

A humidistat is a humidity control device that monitors relative humidity (RH) levels and switches a humidifier or dehumidifier on or off to maintain a desired setpoint. It acts as a simple yet reliable control solution within HVAC systems, ensuring indoor air humidity remains within a defined range.

By automatically responding to changes in air moisture levels, a humidistat helps create a stable indoor environment without the need for constant manual adjustment.

What is the difference between a room humidistat and a duct humidistat?

A room humidistat measures and regulates humidity directly within an occupied space, making it ideal for offices, retail areas, healthcare settings and similar environments. A duct humidistat, on the other hand, is installed inside ventilation ductwork or air handling units to control humidity within the airflow itself.

Selecting the correct type depends on where humidity needs to be measured and controlled. Proper placement ensures accurate readings, reliable switching and efficient humidification performance.

When should a humidistat be used instead of a full humidity controller?

A humidistat is ideal for applications where straightforward on/off humidity control is sufficient. It is commonly used in commercial buildings, light industrial environments and mechanical rooms where maintaining humidity within an acceptable range is more important than achieving extremely tight tolerances.

For projects that require proportional or highly precise humidity regulation, a more advanced controller may be suitable. However, for many standard HVAC installations, a humidistat provides a cost-effective, dependable and easy-to-install solution.

Why is reliable humidity regulation important for buildings and occupants?

Maintaining balanced humidity levels supports occupant comfort, reduces static electricity and helps protect interior finishes, furnishings and technical equipment. Air that is too dry can cause discomfort and material shrinkage, while excessive humidity increases the risk of condensation and mold growth.

A properly specified humidistat ensures consistent humidity control, helping safeguard property value, support indoor air quality strategies and maintain stable building conditions throughout the year.

Get free expert advice

If you want to explore your options for humidity control, Condair's expert sales engineers will visit your site, review your project and talk you through their recommendations.

Alternatively, if you would prefer a call or online meeting, our team are always happy to discuss possible solutions and offer free technical advice.

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