Introduction: ATJ-EN Addressable Multi-Heat Detector and its key features
ATJ-EN (WHT) Addressable Multi-Heat Detectoris an analogue addressable heat sensing device designed for modern addressable fire alarm systems. Built to the Hochiki ESP protocol and carrying EN54-5 approval (Classes A1/B/C) along with LPCB and VdS recognition, the ATJ-EN combines a fixed (variable) temperature element with a rate-of-rise (RoR) sensor. This multi-heat approach gives installers and system designers flexibility: the control panel can be configured to make alarm decisions from the fixed temperature element, the RoR element, or a combination of both.
Key hardware features include low loop power consumption, twin 360° bi-colour LEDs for clear local status indication, and compatibility with common Hochiki bases (for example YBN-R/3). SCI and SIL variants are available as separate SKUs, and LED pulsing behaviour can be controlled centrally from the panel for site-specific needs.
Detailed specifications and benefits
- Sensing:Multi-heat — fixed temperature plus rate-of-rise (RoR) for rapid and reliable heat detection across a range of fire scenarios.
- Protocol:Hochiki ESP addressable digital communications for intelligent loop operation and device supervision.
- Device type / Model:Addressable analogue multi-heat detector, ATJ-EN (WHT).
- Loop voltage:17–41 V DC (ESP loop voltage).
- Low quiescent current:Typical low-power mode around 110 µA; quiescent current approximately 350 µA for most variants. Low power consumption helps maximise the number of devices per loop and minimises load on the fire system.
- Alarm current:Approximately 9.0–9.1 mA (controlled by the panel/CIE) during indicator operation — designed for predictable loop loading when devices go into alarm.
- LEDs:Twin 360° bi-colour LEDs (green when polled, red in alarm) afford excellent local visibility. Panel-controlled pulsing gives centralised control of LED behaviour for aesthetics or to meet site policies.
- Compatibility:Works with standard Hochiki bases such as YBN-R/3. SCI-isolated variants require specific bases (refer to the datasheet for correct base selection).
- Operating temperature:−10 °C to +50 °C.
- Humidity:Up to 95% RH (non-condensing at 40 °C).
- Dimensions:Ø 100 mm × 45 mm high; weight approximately 90–95 g.
- IP rating:Insufficient data supplied — consult the official datasheet for enclosure and environmental sealing details for your chosen variant.
- Approvals:EN54-5 (Classes A1/B/C), LPCB and VdS. SIL-2 and SCI isolator variants are available as separate SKUs and have their own datasheets.
- Finish/colour options:White (WHT) is the pictured model; ivory and black options are typically available for aesthetic matching.
Why these specifications matter:The ATJ-EN’s multi-heat sensing gives a balanced detection profile: fixed-temperature sensing provides dependable protection where sustained heat is the hazard, while rate-of-rise detects sudden temperature climbs that indicate rapidly developing fires. Combined with low loop power, addressable communications and visible LED status, the detector is well suited to intelligent addressable fire systems where both performance and system reliability are essential.
Use cases and scenarios where the ATJ-EN excels
The ATJ-EN is particularly effective in situations where heat detection is preferred or required, where smoke detectors may be unsuitable, or where robust local indication and addressable control are important.
- Commercial kitchens and back-of-house areas:In some kitchen zones smoke and particulate detectors produce nuisance alarms. A properly specified heat detector — especially a multi-heat device that responds to both fixed temperature and RoR — can reduce false alarms while maintaining safety.
- Light industrial premises:Warehouses, light manufacturing and storage areas with dust or fumes that can interfere with smoke detection benefit from heat-based detection. The ATJ-EN’s configurable alarm logic lets integrators tune response to the specific environment.
- Plant rooms and electrical cupboards:Spaces with heat generation but limited visible smoke are prime candidates for heat detectors. The RoR element helps detect fast-developing faults while the fixed temperature element offers long-term protection against smouldering or sustained heating.
- Addressable fire alarm systems in office buildings and retail:For buildings requiring EN54-certified devices and the diagnostic capability of addressable loops, the ATJ-EN provides both certification compliance and easy networked monitoring.
- Sites requiring centrally controlled LED behaviour:Museums, retail or executive suites sometimes require discreet or centrally controlled indicator behaviour — the ATJ-EN supports LED pulsing controlled from the panel to meet such aesthetic or operational needs.
How the ATJ-EN compares with similar products
When selecting detection devices it helps to distinguish by detection principle, installation complexity and loop performance. The ATJ-EN sits in the multi-heat, addressable category and compares as follows:
- Single fixed-temperature detectors are simpler but less flexible. They will alarm only when a threshold temperature is reached. The ATJ-EN’s combined fixed + RoR sensing offers both threshold and dynamic detection — faster response to rapidly developing fires and conservative behaviour in slowly heating environments.
- RoR-only devices are fast to react to sudden temperature climbs but may not capture slowly developing smouldering fires that eventually reach a hazardous steady temperature. The ATJ-EN supports both modes, allowing panel configuration to suit site risk.
- Smoke detectors detect combustion products and are generally more sensitive to early-stage fires producing smoke. However, in dusty, humid, or fume-prone environments they can create nuisance alarms. Heat detectors like the ATJ-EN are less susceptible to such contaminants and are commonly specified where smoke detection is unsuitable or restricted by regulations.
- Multi-criteria detectors combine heat, smoke and sometimes CO sensing for a broader detection net; they are more complex and expensive. The ATJ-EN provides cost-effective, standards-approved heat detection for applications where heat is the primary alarm indicator.
- Compared with other addressable heat devices, the ATJ-EN stands out for its twin 360° LEDs and panel-controllable LED behaviour, low-power operation, and wide loop voltage range. Its EN54-5 certification and availability of safety (SIL‑2) and isolator (SCI) variants make it suitable for regulated installations.
Customer feedback and installer observations
Publicly available customer feedback specific to every SKU may be limited due to the specialist nature of fire safety equipment and installer procurement channels. However, installers and system designers commonly cite these practical benefits when choosing the ATJ-EN family:
- Reliable behaviour on addressable loops:Installers report predictable device addressing and stable communications with Hochiki ESP panels.
- Good local visibility:The twin 360° bi-colour LEDs are frequently praised for making device status immediately obvious from any approach angle, helpful during commissioning and fault-finding.
- Flexible alarm configuration:System integrators appreciate that panels can be configured to use fixed, RoR or combined elements — enabling tailored detection strategies for mixed-risk sites.
- Reduced nuisance alarms:In environments where smoke detectors are problematic, site teams note fewer false alarms when heat-based detection is correctly specified.
Note: Always consult independent reviews, installer case studies or request references from suppliers for project-specific validation. Performance and suitability should be judged against the site risk assessment and local regulations.
Conclusion: Why choose the ATJ-EN?
The ATJ-EN (WHT) addressable multi-heat detector is a compelling choice for projects that require certified heat detection on addressable loops. Its multi-heat sensing (fixed temperature + rate-of-rise), compliance with EN54-5 and other approvals, low loop power consumption, and clear 360° LED indication make it versatile and installer-friendly. The ability to control LED behaviour from the panel and the availability of SIL and SCI variants broaden its suitability across commercial, light industrial and specialist installations.
For systems where smoke detection is unsuitable, or where a balanced heat sensing strategy is preferred, the ATJ-EN provides a standards-compliant, practical solution. Always ensure installation and commissioning are carried out by a competent fire alarm engineer and consult the official datasheet for variant-specific electrical figures, quiescent and alarm currents, mounting instructions and correct base selection.
Summary:If you need a flexible, EN54-5 approved addressable heat detector with modern LED indications, low loop loading and configurable alarm logic, the ATJ-EN is a strong, cost-effective option for many commercial and light industrial fire detection projects.
