Ajax DoorProtect & GlassProtect: The UK Installer's Guide

Ajax DoorProtect is the wireless opening detector at the heart of almost every Ajax intruder system — but on its own it only tells you that a door or window has opened. Pair it with DoorProtect Plus, GlassProtect and CombiProtect and you can catch an intruder at the perimeter, before they are inside and moving. This UK installer's guide explains how each Ajax opening and glass-break detector works, when to fit which, how to bring existing wired contacts onto the same system, and what hub and extras you need to finish the job. Netview is an Ajax stockist and holds the range for same-day dispatch on stocked lines.

What this guide covers

DoorProtect U — wireless reed-switch opening detector for doors, windows and skylights.
DoorProtect Plus U — adds an accelerometer for shock and tilt, catching force, drilling and lifting attempts.
GlassProtect U — acoustic glass-break detector using the DualTone algorithm to cut false alarms.
CombiProtect — motion and glass-break in one housing, with pet immunity up to 20 kg.
All talk to the hub over the encrypted Jeweller radio protocol, with up to 7 years of battery life.

Ajax DoorProtect and GlassProtect perimeter detectors guide for UK installers — Ajax perimeter detection: DoorProtect, DoorProtect Plus, GlassProtect and CombiProtect. Stocked at Netview.

What is Ajax DoorProtect and how does it work?

Ajax DoorProtect is a wireless magnetic opening detector that reports the moment a door, window or skylight is opened, using a reed switch and a paired magnet. When the magnet moves away from the detector body, the reed switch opens and the detector sends an alarm to the hub. The UK-market DoorProtect U Jeweller uses two reed switches, so the magnet can sit on either the left or right edge to suit the way the door is hung, and anti-chatter processing helps prevent false triggers from a rattling door (Ajax DoorProtect U Jeweller). Two magnets of different sizes are included so you can match the reed-to-magnet gap to the frame — the larger magnet tolerates a wider mounting gap than the smaller one. It fits in minutes on the SmartBracket mounting panel, has a tamper that reports removal from the surface, and runs up to 7 years on its pre-installed battery. Fit the white DoorProtect U (white) or the DoorProtect U (black) to match the door. If the system has a siren, DoorProtect can also double as a shopkeeper's chime, sounding one of four tones each time an entrance opens.

DoorProtect vs DoorProtect Plus — what does the Plus add?

DoorProtect Plus adds a built-in accelerometer, so it detects shock, vibration and tilt as well as opening — catching attempts to force, drill or lift a door or window that never actually break the magnetic contact. The shock sensor has three sensitivity levels and can be set to ignore a single isolated impact to keep false alarms down, while the tilt sensor can be armed at an angle from 5° to 25° with an adjustable tilt-alarm delay of one second to one minute (Ajax DoorProtect Plus). That makes the DoorProtect Plus U (white) and DoorProtect Plus U (black) the right choice for vulnerable timber doors, roller shutters, gates, and safes or display cabinets where you want a warning if the item is struck or moved, not just opened. It communicates over Jeweller at up to 1,200 m in open space and runs up to 5 years on its battery — slightly less than the standard detector because the accelerometer draws more power. Use standard DoorProtect for ordinary doors and windows, and DoorProtect Plus where shock or tilt detection genuinely earns its place.

How does Ajax GlassProtect detect a break-in?

GlassProtect is an acoustic glass-break detector that listens for the two-part sound of breaking glass and alarms only when both parts arrive within 1.5 seconds. Its DualTone digital algorithm first needs the dull, low-frequency thud of an impact on the pane, then the ringing, high-frequency sound of the glass actually shattering — requiring both in sequence is what stops a slammed door or dropped keys from setting it off (Ajax GlassProtect). A sensitive electret microphone gives it a 180° listening angle and detection up to 9 m, with three sensitivity levels set in the Ajax app to suit the room. The GlassProtect U (white) and GlassProtect U (black) talk to the hub over Jeweller at up to 1,000 m line of sight and last up to 7 years on the pre-installed battery. One installer caveat worth noting: GlassProtect will not respond to the breaking of glass covered with shatterproof, solar, decorative or any other film, because the film changes the acoustic signature — on filmed glazing, rely on a DoorProtect contact or shock sensor instead.

CombiProtect — motion and glass-break in one device

CombiProtect combines a PIR motion sensor and an acoustic glass-break detector in a single housing, covering both the approach to a window and the glass itself from one mounting point. The PIR element detects movement out to 12 m across an 88.5° horizontal field, while the same DualTone glass-break stage as GlassProtect listens for a break up to 9 m away (Ajax CombiProtect). It is pet-immune to animals up to 20 kg and below 50 cm in height when mounted correctly at about 2.4 m with the lens perpendicular to the likely intrusion path, and runs up to 5 years on its battery. Fit the CombiProtect (white) or CombiProtect (black) in a room with a large window where you want one device to cover both the space and the glazing. For rooms that only need volumetric cover, a standalone PIR is usually the better value — see our Ajax MotionProtect vs Pyronix KX comparison.

The four detectors at a glance

The table below is the quick reference for choosing between the Ajax perimeter detectors Netview stocks.

Detector	Detects	Range	Battery	Best for
DoorProtect U	Opening (reed switch)	1,200 m Jeweller	Up to 7 years	Doors, windows, skylights
DoorProtect Plus U	Opening + shock + tilt	1,200 m Jeweller	Up to 5 years	Vulnerable doors, shutters, safes
GlassProtect U	Glass break (acoustic)	9 m detect / 1,000 m Jeweller	Up to 7 years	Large windows, shopfronts, glazed façades
CombiProtect	Motion + glass break	12 m PIR / 9 m glass	Up to 5 years	Rooms with a window and pets

Ajax perimeter detectors compared: DoorProtect, DoorProtect Plus, GlassProtect and CombiProtect — Match the detector to the risk: opening, shock and tilt, glass break, or motion plus glass in one.

Perimeter-first alarm design: why detect at the boundary

Perimeter detection catches an intruder at the point of entry — the door, window or glass — rather than waiting for them to cross a motion sensor once they are already inside. The professional approach is layered: an opening detector on every accessible door and window, a glass-break detector covering large panes and shopfronts, and volumetric motion sensors inside as the final trap. The perimeter layer gives the earliest possible warning and, because a contact only reports a genuine opening, it produces far fewer nuisance alarms than motion sensors alone. It also unlocks night or 'stay' arming: with DoorProtect and GlassProtect guarding the shell, the household or night staff can move freely inside while the perimeter stays live. Build the detector list around the building's actual entry points first, then add interior cover — our Ajax StarterKit guide shows how the core devices come together into a working system.

Bringing wired and legacy detectors onto Ajax

You can integrate existing wired perimeter contacts into an Ajax system without rewiring the whole site, using either the detector's onboard terminal or a dedicated transmitter module. Each DoorProtect, DoorProtect Plus and GlassProtect has a socket for one third-party wired detector with a normally-closed (NC) contact — an opening, motion or vibration device — which then reports through Ajax in the same app interface, though the Ajax detector cannot power that wired device, so it needs its own supply (Ajax DoorProtect U Jeweller). Where a panel has many wired zones, the Ajax MultiTransmitter brings up to 18 wired third-party detectors onto Jeweller in one module, and the Ajax Universal Transmitter adds a single wired device such as a shock sensor or roller-shutter contact. This is how you retrofit Ajax over a legacy hard-wired system in stages. For the full walkthrough, read our Ajax MultiTransmitter installer guide.

What hub and extras do you need?

Every Ajax detector needs a hub as the system's brain, and the chime and arming features need a siren and a keypad. The detectors in this guide pair with any Ajax hub; the Ajax Hub 2 Plus adds Wi-Fi and dual-SIM LTE alongside Ethernet for the most resilient communications, while a standard Hub 2 suits smaller installs — our Hub 2 vs Hub 2 Plus comparison helps you choose. A system can take up to five range extenders to reach outbuildings and thick-walled areas. The DoorProtect chime feature needs an Ajax siren to sound the tone (see our Ajax sirens guide), and users arm or disarm from the app, a keyfob or a keypad — compare the options in our Ajax keypad comparison. If you want visual confirmation of an alarm, add a MotionCam alongside the perimeter devices, as covered in our Ajax MotionCam photo verification guide.

How to plan Ajax perimeter protection in four steps — Four steps to spec Ajax perimeter cover: map entry points, choose detectors, integrate wired zones, add the hub.

Installation, range and battery tips

Ajax perimeter detectors install in minutes on the SmartBracket and pair by scanning a QR code, but a few placement choices decide reliability. Mount DoorProtect on the frame with the magnet on the opening edge, and pick the larger included magnet if the gap is wide; set DoorProtect Plus's tilt angle between 5° and 25° for gates and shutters that swing or lift. Place GlassProtect within 9 m and line-of-sight of the glazing it protects — not hidden behind heavy curtains — and mount CombiProtect at about 2.4 m with its lens across the intrusion path. Check the Jeweller link on the hub before you leave: it reaches up to 1,200 m in open space but far less through steel and concrete, so add range extenders (up to five per hub) on larger sites (Ajax Jeweller radio protocol). At the minimum polling interval the system detects a lost device in about 36 seconds, and every detector reports its own battery, tamper and signal status, with low-battery warnings arriving months ahead of replacement.

FAQ

Is Ajax DoorProtect wired or wireless?
DoorProtect is fully wireless. It communicates with the Ajax hub over the encrypted Jeweller radio protocol at up to 1,200 m in open space and runs up to 7 years on its pre-installed battery, so there is no cabling to the detector.

Do I need DoorProtect or DoorProtect Plus?
Use standard DoorProtect for ordinary doors and windows where you only need to know they have opened. Choose DoorProtect Plus where shock and tilt matter — vulnerable doors, roller shutters, gates, safes and display cabinets — because its accelerometer detects force, drilling and lifting.

How far can Ajax GlassProtect detect a break?
GlassProtect detects glass breaking up to 9 m away across a 180° angle. Mount it within line of sight of the glazing it protects and set one of the three sensitivity levels in the Ajax app to suit the room.

Will GlassProtect false-alarm on a slammed door or dropped keys?
It should not. The DualTone algorithm requires both the dull low-frequency impact and the ringing high-frequency shatter within 1.5 seconds before it alarms, so single everyday noises do not trigger it.

Can I connect my old wired door contacts to Ajax?
Yes. Each DoorProtect, DoorProtect Plus and GlassProtect has a terminal for one third-party NC detector, and the MultiTransmitter brings up to 18 wired detectors onto Ajax at once, so you can retrofit over a legacy system in stages.

Which Ajax hub do these detectors need?
Any Ajax hub. Hub 2 suits smaller installs, while Hub 2 Plus adds Wi-Fi and dual-SIM LTE for resilient communications. Add up to five range extenders to reach outbuildings or areas with thick walls.

Shop the Ajax perimeter range at Netview

We stock Ajax DoorProtect, DoorProtect Plus, GlassProtect, CombiProtect and the hubs, sirens and transmitters in this guide, with same-day dispatch on stocked lines. Browse the brands we stock and order online at netviewcctv.co.uk.

Published 2 July 2026 · Netview CCTV · Leicester. Specifications are taken from manufacturer sources, linked inline, and were correct at the time of writing.

July 2, 2026 | View: 13 | By: netviewcctv.co.uk