Humidity sensor

Our HYGRASGARD® humidity sensors for indoor and outdoor use measure the relative humidity and temperature of the ambient air. The sensor device calculates various values from these measured variables: relative humidity [% r.H.], absolute humidity [g/m³], mixing ratio [g/kg], dew point temperature [°C], enthalpy [kJ/kg] and room temperature [°C].

Guide and interesting facts about humidity sensors

Humidity sensor guide

A look back

Before the development of electronic sensors, hygrostats and hygrometers were actually operated with horsehair. Degreased hair reacts to humidity by lengthening - or shortening - as the humidity rises, thus mechanically moving a switch or pointer. This analog measurement technology formed the basis for the first automatic ventilation or dehumidification systems and is still used today in a simplified form for training or demonstration purposes.

What is healthy indoor air?

Free from harmful substances
Pleasant temperature of 20 - 22°C
Humidity of 40 - 60 % RH (relative humidity or relative Humidity)

Inhalt

Why is a humidity sensor useful? Consequences of excessive humidity How do humidity sensors work? What are the advantages of combi appliances? Applications What variants of humidity sensors are available? Advantages of S+S humidity sensors Conclusion

Why is a humidity sensor useful?

Humidity is constantly changing due to breathing, showering, cooking, temperature changes, the number of people and the presence of plants. A single person emits Tag over 1.5 liters Humidity a family of 4 even up to 12 liters. If this moisture is not removed by ventilation, mold and structural damage will occur in the long term.
Humidity sensors record the relative humidity and help to detect critical fluctuations at an early stage. Humidity that is permanently too high or too low can lead to health problems, mold growth or structural damage. Sensors detect these conditions at an early stage and transmit precise measurement data to your HVAC or automation systems.

What are the consequences of incorrect humidity levels in rooms?

The consequences of too low/high humidity are not immediate. Rather, it is a gradual process and the result of permanently incorrect indoor air. A distinction must be made between health consequences and structural consequences (for buildings and structures).

Health consequences

< optimum humidity
Drying of the skin: Irritation of the eyes, skin and mucous membranes occurs from a humidity of <40%
Weakening of the immune system: Pathogens survive longer in dry air and spread more easily. Apart from that, the mucous membranes are easier to attack.
Electrostatic charge: Touching metal objects causes a (slight) electric shock, as dry air charges more quickly.
> Optimum humidity
Ideal environment for parasites: Fungi, mites and other pests multiply from an air humidity of >80%.
Respiratory illness caused by mold (or the inhalation of mold spores): At a sustained humidity of >60%, mold growth is encouraged; at a humidity of 70%, it is almost unavoidable.
Circulatory problems: It is more difficult to cool the body - sweat evaporates more slowly (air can only absorb liquid to a limited extent) so that the body temperature is not lowered.
Substances hazardous to health: Damp furnishings (e.g. wallpaper, paints) can release chemical substances into the air that are irritating or harmful to health.

Consequences for buildings

< optimum humidity
Structural damage due to dryness: Wood in particular is damaged and warped by insufficient humidity.
Cracking in walls/ceilings: Excessively low humidity causes materials such as plaster and plaster to dry and crack. Cracks can also form in masonry or plasterboard.
Dry seals and joints: Seals on windows, doors or in pipes can become brittle if the humidity is too low and lose their sealing effect, which can lead to draughts or water damage.
> Optimum humidity
Formation of mold: The building fabric of the property is attacked by mold.
Damage to furnishings caused by Humidity and mold: The furnishings often have to be replaced after a mold infestation.
Development of severe moisture damage (sponge): Which can lead to the demolition of the building.

And how do humidity sensors work?

Humidity sensors measure relative humidity in different ways - depending on the type of sensor used. Capacitive sensors are particularly common in the HVAC sector: They work with a moisture-sensitive material whose capacitance changes due to water vapor and are considered robust, low-maintenance and durable. Thermal humidity sensors use temperature differences between dry reference air and ambient air and deliver particularly precise results in sensitive applications. Resistive sensors measure the electrical resistance of a hygroscopic material and are often used in environments with chemical exposure. Each technology has its own specific advantages - it is important to choose the right type depending on the application.

To summarize:

Capacitive: Robust, durable, standard in HVAC
Thermal: Highly accurate for special requirements
Resistive: For special cases with chemical exposure

What values/characteristics does a sensor record for Humidity and temperature?

A room temperature sensor / humidity sensor measures the relative humidity and temperature of the room air. The humidity sensor calculates various values from these measured variables. The following parameters, for example, can be queried via the Modbus interface: relative humidity [% RH], absolute humidity [g/m³], mixing ratio [g/kg], dew point temperature [°C], enthalpy [kJ/kg] and room temperature [°C].

What are the advantages of combined temperature and humidity measuring devices?

The interplay of temperature and humidity has a twofold effect on our well-being:
On the one hand, high indoor humidity poses a risk to the building fabric due to mold infestation. Particularly in cold rooms such as factory halls, warehouses or cellars, the humidity condenses. Humidity on the walls and thus promotes mold growth. Inadequate ventilation and incorrect heating can also lead to mold growth. The effects range from damage to individual building components and the infestation of objects to health problems for residents.
On the other hand, humidity has an impact on our personal well-being, especially in summer temperatures: If the humidity is high, a greenhouse effect is quickly created and people feel uncomfortable. On the other hand, if the indoor humidity is too low, this can quickly have health consequences, as mucous membranes and respiratory tracts suffer.

It is therefore worth keeping an eye on both factors at all times. Sensors for measuring temperature and humidity from S+S help you to do this. Take a look at our humidity sensors / humidity detectors.

Did you know:

Dew point control against summer humidity
An intelligent ventilation system with a humidity and temperature sensor can also ensure optimum moisture protection in summer. Example: The sensor detects that warm summer air would condense in the basement and automatically prevents ventilation - this saves structural damage and mold.

Applications in HVAC and building automation

Our humidity sensors are used in a wide range of applications:

Indoor air measurement in offices, hotels, conference centers
Duct moisture measurement in supply and exhaust air systems
Outdoor air monitoring to detect climatic and weather influences for demand-based control of ventilation and air conditioning systems
Greenhouses, cellars, clean rooms: precise climate control
Clean rooms for constant humidity for precise processes

Even extreme conditions such as swimming pools, industrial halls or cold rooms are no problem for our robust sensors (up to IP65).
AFTF-35/ KFTF-35 have been developed for the high humidity range (95...99% RH) and are protected against condensation.
With the AFTF-45/ KFTF-45, both the housing and the sensors are IP65 and are therefore not only dustproof, but also protected against water jets from all directions.

Sensor variants for every need

Room humidity sensors are used to monitor the humidity in indoor rooms such as offices, hotels or conference rooms (surface-mounted or flush-mounted devices)
Duct humidity sensors are designed for the precise measurement of humidity (and temperature) in air ducts or fans, e.g. in refrigeration, air conditioning, ventilation or clean room technology
Outdoor humidity sensors are often used in combination with temperature sensors - to protect buildings from moisture damage
Pendulum sensors can easily monitor high rooms (e.g. greenhouses, galleries or museums) using pendulum or flush-mounted humidity sensors (for installation in suspended ceilings)
Screw-in humidity sensor for compressed air lines

Many models also measure temperature and automatically calculate other values such as dew point, absolute humidity or enthalpy. Bus systems are also supported: for example with Modbus RTU or wireless W-Modbus (Wireless Modbus).

Advantages of S+S humidity sensors

High measuring accuracy (typ. ±1.8 - 2% RH)
Robust design (protection class IP30 to IP65)
Combination sensors for humidity + temperature
Retrofit and system compatibility (e.g. 0 - 10 V, Modbus)
5-year guarantee - Made in Germany

Discover the right humidity sensor now: To the humidity sensor overview

Conclusion

Humidity sensors not only improve comfort, but also reduce energy consumption and prevent mold growth. They are particularly indispensable in HVAC systems and smart buildings. Discover our product world - or get advice on which humidity sensor is right for your project.

Whether for the smart home or industrial systems - with S+S Regeltechnik With the HYGRASGARD® and HYGRASREG® series, you will find reliable, durable sensors for your building management system (BMS).

Your demand is our motivation!

We develop and manufacture our humidity sensors directly at the S+S headquarters in Nuremberg and guarantee the highest quality for trouble-free operation and a long product life. Our stock items are usually dispatched by DHL within 1-2 working days.
Order humidity probes or humidity sensors online at SplusS.de - quickly and easily! In our online store you will find humidity sensors, humidity transducers and combination devices for almost every application. The convenient menu navigation makes it easy for you to find the device you are looking for.

Do you have any questions about the product?

Our service team is always available by phone or email to help you navigate and shop online. Find the right humidity sensor for your application today!

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We also manufacture individually

Do you have special requirements? As a manufacturer with our own production in Germany, we are always able to produce outside the standard range.

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Humidity sensor

Humidity sensor guide

A look back