Gira hygrostat

Features, function

The Gira hygrostat detects the humidity and temperature in the room with internal sensors. If the humidity exceeds the setpoint value set on the rotary knob, the Gira hygrostat switches on an externally connected fan to dehumidify the room. In the process, the device treats the setpoint value dynamically, i.e. it considers the effect that warmer air can absorb more moisture than colder air within certain limits. For example, if the Gira hygrostat measures a higher room temperature than the reference temperature of 21 °C, it permits a correspondingly higher humidity. This avoids unnecessary ventilation and saves energy.

Standby mode

Runtime monitoring function prevents excessively long ventilation when the ambient air is too humid, e.g. when thunderstorms are possible. To prevent unrestricted operation of the connected fan, the Gira hygrostat changes to standby mode after approx. 1 hour. Then the fan is switched off for approximately 4 hours. If the humidity is still too high after 4 hours, the fan is switched on again. This operating mode is signalled with a red LED and can be manually influenced using the operating button.

Fixed setpoint control

The Gira hygrostat can be set to fixed setpoint control on the back of the device in order to prevent unauthorised modifications to the humidity setpoint value, for example in rental flats or public buildings. The setpoint value is then permanently set to 60 % relative humidity, regardless of the position of the rotary knob on the front of the device.


For optimum operation, the installation location should be at a height of approx. 1.5 m, free of direct exposure to sunlight, draught air or heat radiated from electrical devices, and it should not be directly in the radiation area of heaters. It is also recommended not to install the Gira hygrostat in a unit with electrical devices that produce heat (e.g. dimmers). A moisture-absorbing surface (e.g. sheetrock) can affect the control behaviour, and therefore installation on a surface that does not absorb moisture is recommended, such as tiles. In bathrooms spacing must be observed in accordance with DIN VDE 0100-701.

Technical data

Control range
20 % to 95 % rF
Measurement tolerance
± 5 % rF
Switching differential
± 2 % fixed
Operating voltage
230 V AC/ 50 Hz
Relay output
potentially charged (NO contact)
max. permissible switching current
8 A (cos φ = 1)
or 4 A (cos φ = 0.6), 230 V AC
Operating temperature
0 to +50 °C
Protection type
IP 20

Air conditioning/heating control