You have probably noticed it when you stayed in hotel rooms: as soon as you open the room window because you want to let a little air into the room, the heating stops. When you close the window, the heating starts up again. This is a deliberate choice on the part of the hotel management to prevent wasting energy. The technology used here is window contacts. You can install these same devices in your home as well, or they may have already been installed for the burglar alarm system. Let’s take a look at the possibilities.
What is it?
Every window or door contact consists of two parts. The first contains the hardwired contact. The second part is a magnet. When the two parts are brought into proximity, for instance with a closed window, the contact will set to a certain status, open or closed, depending on the design and connection. When the magnet is moved further away from the contact, by opening the window, the contact will take another status. This then enables us to detect if a window or door is open or closed.
A built-in window contact. Left is the contact part, right the cylinder with the magnet. (Photo source: Aliexpress)
Built-in or surface-mounted
If you place new windows or doors with new building work or a renovation, it is advisable to have the contacts built into the windows or doors. Ask your installation firm to provide the necessary setup, and the magnetic part will then be built into the moving part of the window. The contact part is mounted in the fixed part of the window or door because that is where the connections are made. For existing windows and doors, you can opt for surface-mounted contacts.
Example of a surface-mounted window contact. (Photo source: Aliexpress)
How many wires?
In principle, two wires are sufficient for the contact to pass on information to, for instance, an Integrated Home System (IHS). However, if the window contacts are part of a burglar alarm system they will have two extra wires. These are for the tamper switch. If this wiring is cut the alarm centre will be immediately alerted.
What functionalities can you carry out?
As mentioned earlier, we can realise energy savings as soon as a window is opened. Specifically, the zone heating for that particular space will then be switched off. On closing the window, the heating will start working again.
It can also be handy and safer when leaving the home or going to bed to be notified if a window or door has been left open. By pressing the “I am leaving the house” key or the “sleep tight” key, a signal can be sent in various different ways to alert the resident when a window has been left open. This can be a flashing light or a flashing LED incorporated in the control button. A simple buzzer or sending a text message to your mobile phone are also possibilities.
Besides windows and doors, such contacts can of course also be used for the garage door, a gate at the back of the garden, a gated bike shed, etc. Consult your IHS installer for more information: they can take care of the integration with the IHS and coordinate with the firm responsible for installing your windows and, if applicable, work with your burglar alarm system installer.