How well a presence sensor detects depends half on where it is mounted. Here you can read where best to mount a presence sensor, what to watch for on the ceiling, on the wall, and in the corner of the room, how to power it, and what to set after installation.
In short: where do you mount a presence sensor?
On the wall at a height of 1.50 to 2.00 m, with a clear view into the room, or on the ceiling in the middle of the room. In many rooms, the corner of the room at the same height is the best choice: from there the presence sensor looks diagonally into the room and often covers it more completely. Avoid a direct view of fans, curtains in front of open windows, and radiators.
| Wall | Corner of the room | Ceiling | |
|---|---|---|---|
| Height | 1.50 to 2.00 m | 1.50 to 2.00 m | Middle of the room; the higher the ceiling, the larger the covered area |
| Viewing direction | into the room, a fan of 120° or 150° | diagonally across the whole room | downward, circular |
| Good for | rooms you can overlook from one side, long rooms | square rooms, living rooms, bedrooms | rooms with furniture along all walls, hallways |
| Setting afterwards | mounting type “Wall” | mounting type “Wall” (on the KL MZ “Wall / corner”) | mounting type “Ceiling” |
Mounting on the ceiling
On the ceiling, the presence sensor looks down on the room from above, and furniture hardly blocks it. The higher the ceiling, the larger the covered area: with a ceiling height of 2.50 m, a 24 GHz presence sensor covers a circle about 8 m in diameter. After installation, set the mounting type to “Ceiling” in the interface so that the distances and, on the KL MZ, the zones are calculated correctly.
The Senvolon presence sensors are built for surface mounting: two screws hold the housing, and the cable can be routed out of sight through the back. A flush-mounted box is not needed.
Mounting on the wall
On the wall, the presence sensor belongs at a height of 1.50 to 2.00 m, facing into the room. At this height it looks over tables and sofa backs and detects people who are sitting or lying down. Do not hang it right next to a window with a curtain or opposite a ceiling fan. If the cable on the KL MZ comes from above instead of from below, mirror the detection area horizontally in the settings.
Mounting in the corner of the room
Mounted in the corner, the presence sensor looks diagonally into the room. The detection fan then lies over the whole floor area instead of only in front of one wall, and the corners next to the device matter less. For square rooms this is often the best position.
What to avoid during installation: typical causes of false triggers
- Moving objects in view: fans, curtains in a draft, plants above a radiator. On the KL MZ you hide such spots with interference zones, on the KL, KL LD, and the base model via range and sensitivity.
- Robot vacuum: it is detected as long as it is moving and cannot be hidden with a zone because it travels through the whole room. With a lower sensitivity the presence sensor no longer reacts to the robot, but then it also detects people sitting still less reliably. Alternatively, ignore the signal in your automation while the robot is cleaning.
- Thin walls to the next room: radar waves can pass through light materials such as drywall, wood, or glass. Set distance and sensitivity so that the presence sensor ignores movement behind the wall, on the KL MZ additionally with a room boundary.
- Large metal surfaces directly in front of the device: they reflect the radar and disturb the measurement.
- Weak Wi-Fi: check the reception at the mounting location beforehand, for example with your smartphone.
- Outdoor and wet areas: the housings are not waterproof, so in the bathroom mount them outside the splash zone.
Power supply
All Senvolon presence sensors run on 5 V. Each one comes with a USB-C cable, and the KL, KL LD, and KL MZ additionally come with a connection cable with a JST connector and open ends for powering the device from the back. A power adapter is not included.
- KL, KL LD, and the base model: USB power adapter with 5 W or more (5 V, 1 A). Any common smartphone charger is enough.
- KL MZ: USB power adapter with 10 to 15 W (5 V, 2 to 3 A) and a USB-A port. A charger with only 5 W is too weak.
- Hidden from the back: instead of USB-C, the presence sensor can also be connected inside the housing: the KL, KL LD, and KL MZ via a connector (JST PH 2.0), the base model via a screw terminal. This is also where you find the switching output, which delivers 3.3 V when presence is detected.
The presence sensor gets slightly warm during operation, which is normal. Temperature and humidity are therefore only accurate after about 30 minutes; if needed, adjust them with an offset under System.
Settings after installation
Set the mounting type first: choose “Ceiling” or “Wall” in the presence sensor's interface before you create zones. On the KL MZ, changing the mounting type later resets all zones. For setup, set the timeout to a few seconds so that you see every change right away.
KL, KL LD, and the base model: range and sensitivity
The presence sensor divides the room into gates by distance. Under More, Settings you set the length of a gate (0.75 m by default, or 0.2 m) and the number of gates (0 to 8); together they give the maximum detection distance. Set this first so that the presence sensor ends at the opposite wall.
For each gate there are separate thresholds for motion and for stationary presence (More, Motion Gates and Stationary Gates). 0 % means everything is detected, 100 % excludes the gate. Set the thresholds so that the level displayed in the empty room is just below them, and then test: enter the room, sit down, stay still. The first two gates of stationary presence cannot be changed for technical reasons. The presence sensor detects stationary presence after it has seen motion once.
| Gate | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|---|
| Motion, factory setting | 50 | 50 | 40 | 30 | 20 | 15 | 15 | 15 | 15 |
| Stationary, factory setting | 0 | 0 | 40 | 40 | 30 | 30 | 20 | 20 | 20 |
KL MZ: zones
On the KL MZ you draw zones directly on the radar view of the interface or teach them on site; with “Learn room” it creates interference zones around sources of interference itself, and the boundary makes detection end at your walls. Step by step: Setting up zones on the KL MZ presence sensor.
Frequently asked questions about installation
Can I hide the presence sensor behind a panel?
Yes. Radar waves can pass through light materials such as drywall, wood, or glass, so concealed mounting is possible. Metal in front of the device disturbs the measurement. Test the detection before you close the panel for good.
Which height is right on the wall?
1.50 to 2.00 m. Any lower and furniture quickly blocks the view.
Surface-mounted or flush-mounted?
The Senvolon presence sensors are flat surface-mounted devices, 15 to 17 mm high. The cable can come from the back out of sight, and no flush-mounted box is needed.
Can I use the presence sensor outdoors?
No. The housings are built for indoor use only.
The overview of all presence sensors shows which model suits your room. How to integrate the presence sensor into Home Assistant after installation is explained in Presence sensor for Home Assistant.