An Ajax alarm is only as good as its detectors. A poorly chosen or poorly placed model triggers needless alerts or, worse, leaves a passage unmonitored. This guide explains which Ajax detector to choose for each room or entrance, where to mount it and how many to plan for a home or a shop.
The four families of detectors
There are four uses. Each answers a different question.
- Motion: has someone entered the room?
- Opening: has a door or window just opened?
- Glass break: has a window just been smashed?
- Outdoor: is someone approaching the building?
A complete system combines several families. All models are in the Ajax detectors collection.
Quick selection table
| Need | Detector | Price incl. VAT |
|---|---|---|
| Motion in a standard room | MotionProtect | €79.34 |
| Motion in a conservatory, garage or room with draughts or sun | MotionProtect Plus | €109.51 |
| Motion with photos on every alarm | MotionCam | €174.00 |
| Photo on demand | MotionCam PhOD | €192.80 |
| Door or window opening | DoorProtect | €46.04 |
| Front door (shock and tilt) | DoorProtect Plus | €69.07 |
| Glass break | GlassProtect | €79.34 |
| Motion + glass break in one unit | CombiProtect | €109.51 |
| Outdoor (garden, facade) | MotionProtect Outdoor | €273.69 |
| Outdoor with photos | MotionCam Outdoor | €334.02 |
| Water leak | LeaksProtect | €62.70 |
Motion detectors
The MotionProtect is the basic detector: a passive infrared sensor with a 12 m range. Its pet immunity is adjustable, which suits households with a cat or small dog. It runs for several years on a battery.
The MotionProtect Plus adds a second technology, microwave, on top of infrared. It limits false alerts where infrared alone hesitates: conservatory, sunlit room, draughts.
The MotionCam takes photos on every alarm and sends them to the app. You see what triggered the alert, which avoids disturbing anyone needlessly. It is only compatible with the Hub 2 and Hub 2 Plus hubs. The PhOD version takes the photo on demand. To decide between these models, read MotionProtect or MotionCam.
Opening detectors
The DoorProtect is a magnetic contact: a magnet and a sensor. When the door moves away, the alert goes off. It is used on every exterior door and on accessible windows.
The DoorProtect Plus adds shock and tilt detection. It reacts when someone forces or shakes the door, even before it opens. It is the right choice for the front door and the garage door.
In an apartment, a contact on the landing door plus a motion detector in the hallway is often enough. In a house, plan one contact per ground-floor entrance.
Glass-break detectors
The GlassProtect listens for the sound of breaking glass with a microphone. It is useful for a large glass door, a shop window or a room with several windows: a single unit covers several panes.
The CombiProtect combines motion and glass break in one unit. It is handy in a living room or a shop with a large window, at a lower price than two separate devices.
Outdoor detectors
The MotionProtect Outdoor uses dual infrared with anti-masking. It detects a presence before the intruder reaches the building: terrace, driveway, garden. The MotionCam Outdoor adds photos. These models create a first line of defence. Choose them for an isolated house or a site with a yard.
Choosing room by room
| Room or entrance | Recommended detector |
|---|---|
| Entrance hall | MotionCam or MotionProtect, and DoorProtect Plus on the door |
| Living room with large glazing | CombiProtect or MotionProtect + GlassProtect |
| Kitchen | DoorProtect on the door leading outside |
| Conservatory | MotionProtect Plus |
| Garage | DoorProtect Plus on the door, MotionProtect Plus in the room |
| Upstairs bedroom | None if you arm in partial mode at night; otherwise MotionProtect |
| Cellar | LeaksProtect if there is a flood risk |
| Garden, terrace | MotionProtect Outdoor |
How many detectors to plan for?
The basic rule: one motion detector per compulsory passage area, one opening contact per exposed entrance.
- Studio: 1 motion detector and 1 contact on the door.
- Apartment: 2 to 3 detectors in total.
- Detached house: 4 to 6 detectors, counting door contacts.
- Shop: one motion detector per area (shop floor, stockroom), one contact per door, one glass-break detector for the window.
For a full budget, see the price of an Ajax alarm by setup.
Mounting rules
- Mount the motion detector at about 2.4 m high.
- Aim it so the intruder crosses the detection field rather than walking straight towards it.
- Avoid a sunlit window, a radiator, an air conditioner and a moving curtain.
- Do not put tall furniture in front of the sensor.
- Test the radio signal in the app before drilling. Jeweller reaches up to 2,000 m in open field, but walls reduce the range.
- If the signal is weak, a ReX 2 extends coverage.
Sirens and keypads have their own rules: outdoor siren high and visible from the street, indoor siren outside the protected room, keypad inside near the entrance. Find them in the Ajax sirens and Ajax keypads collections.
Hub compatibility
All the detectors mentioned pair over Jeweller radio. The only exception to check: the MotionCam works with the Hub 2 and Hub 2 Plus. If you change hubs later, devices re-pair on the new Hub. Choosing the hub is covered in which Ajax alarm to choose.
Frequently asked questions
Does a motion detector react to pets?
The MotionProtect offers adjustable pet immunity. For a cat or small dog, enable it and mount the detector at the recommended height.
Do I need a detector on every window?
No. One motion detector per passage area covers the interior. Contacts go on easily accessible windows.
What is the difference between DoorProtect and DoorProtect Plus?
The Plus adds shock and tilt detection, useful on the front door.
Can I fit the detectors myself?
Yes for your own home: scan the QR code in the app and allow half a day. For a third party or a shop, use an approved company.
Does an outdoor detector replace an indoor one?
No, it warns earlier but does not monitor the inside. The two complement each other.
Going further
Looking for a complete system? Discover our selection of Ajax alarms in Belgium or the ready-to-fit alarm kits. For professional installation, see installation and services, or call 0800 37 087.