An open window and a sudden shower: without a rain sensor, water quickly collects on the windowsill, in the office or in the hall. A rain sensor reports precipitation to the window control, which then closes the electric window actuators automatically. Here you can find out how a rain sensor for windows works, what it needs and what to look out for when selecting and installing it.
In brief: A rain sensor reports precipitation to the window control unit, which then closes all connected actuators. It does not switch the actuators itself and always needs a control unit with a sensor input, such as the VS-C24-7A. For exposed windows, a wind and rain sensor is the better choice.
How a rain sensor works
There is a contact grid on the surface of the sensor. When raindrops hit it, they connect the conductor tracks and the sensor sends a signal to the control unit. The control unit moves all connected actuators to the closed position. Once the rain stops and the sensor has dried, ventilation can resume, via push button or automatically, depending on the control unit.
Important: the rain sensor does not switch the actuators itself. It always needs a control unit that evaluates its signal, for example the VS-C24-7A controller for 24 V actuators.
What you need for automatic rain protection
- Electric window actuators: chain, spindle or rack-and-pinion actuators that move the window.
- A control unit with sensor input: It supplies the actuators and evaluates the rain signal.
- The rain sensor: mounted outdoors, for example the VS-RS rain sensor.
- Instructions: a ventilation push button or a radio remote control, so that the window can be opened in dry weather.
How control unit, push buttons and sensors work together is explained in the guide Window control.
Rain sensor or wind-rain sensor?
A pure rain sensor only reacts to precipitation. For windows in exposed locations, on the roof or on high facades, a combined sensor that also detects wind is worthwhile. Strong wind can stress open sashes and actuators, even without rain. The VS-WRLS-wind-rain-light sensor measures wind, rain and brightness and is also suitable if awnings or blinds are connected to the same control unit.
| Situation | Recommendation |
|---|---|
| Fanlight or tilt window in the facade, sheltered location | Rain sensor |
| Roof window, skylight dome, strip window on the roof | wind and rain sensor |
| Windows and sun protection on one control unit | Wind-rain-light sensor |
Installing the rain sensor correctly
- Fully exposed to rain: The sensor must be hit directly by the rain. Do not mount it under roof overhangs, canopies or trees.
- Slightly inclined: This lets the water run off and the sensor dries faster after the rain.
- Close to the windows: Mount the sensor on the side of the building where the windows it is meant to protect are located.
- Easily accessible: Leaves and dirt on the contact grid can trigger false signals. Choose a location where the sensor can be cleaned.
- Connection by a qualified electrician: The wiring to the control unit belongs in expert hands.
Typical mistakes
- Sensor mounted in a rain shadow: the window stays open even though it is raining.
- Sensor connected directly to a 230 V line or to an actuator instead of the control unit.
- Too many actuators on one control unit: the control unit cannot supply the current of all actuators and does not close reliably.
- Rain sensor mistaken for fire protection: it is intended for comfort ventilation, not for smoke and heat exhaust (SHEV).
Rain sensor and SHEV
Many SHEV windows are also used for daily ventilation. In that case, a rain sensor closes the windows in ventilation mode. In the event of fire, however, the SHEV control panel always has priority and opens the windows regardless of the weather. This function is performed by an approved SHEV control panel, not by a ventilation control. Find out more in the guide SHEV and daily ventilation.
Read more: Window Actuators and Burglary Protection: Tightness, Locking, Power Failure
Suitable control: the VS-C24-7A controller It drives up to 10 drives together (depending on the power consumption), plus shutters and roller shutters. More about it: Automatic conservatory ventilation.
If an actuator no longer responds, our guide helps: Window actuator won’t open.
Frequently asked questions
Can I retrofit a rain sensor?
Yes, if the existing control unit has an input for a rain sensor. For windows that have so far only been switched via a 230 V push button, a control unit is also required. Tips on retrofitting can be found in the guide Retrofitting electric window openers.
Do all windows close at the same time?
All actuators connected to the same control unit close together when it rains. If parts of the building are to react separately, they need their own control units or a building management system.
Can I still open the window when it rains?
That depends on the control unit. With many control units, the rain signal blocks opening as long as the sensor is wet. How your control unit behaves is described in its manual.
Suitable products and advice
Rain sensor, wind-rain-light sensor, control units and push buttons can be found in the category Window control and ventilation control. Not sure which combination suits your windows? Write to us using the Contact form, and we will put together the right solution for you.