Smoke detector for ventilation ducts Calectro UG8-E-24 and UG8-E-230 – a modern solution for HVAC systems

Smoke detectors installed in ventilation ducts are a key component of fire safety systems in buildings. Their purpose is to quickly detect smoke inside ventilation ducts—before it spreads further through the system. One of the most advanced devices of this type is the Calectro UG8-E-24, available from DACPOL, designed with reliability, ease of installation, and long-term operation without false alarms in mind. Also available in a 230 V AC version: Calectro UG8-E-230.

The UG8-E is available in two variants differing in the type of sampling tube:

• plastic tube PST195 – supplied as standard
• aluminum tube ST280 / ST580 – available separately, for installations requiring a longer tube or individual adjustment

Fig. 1. UG8-E-24 with PST195 tube

Fig. 2. UG8-E-24 with ST280 / ST580 tube

Design and intended use of the detector

The Calectro UG8-E consists of a housing mounted on the ventilation duct and an optical smoke detector located in a specially designed airflow chamber. The design ensures optimal airflow through the detection chamber, significantly improving smoke detection efficiency.

The device can be rotated 360°, making installation easier in difficult locations. The housing also features an airflow direction arrow, eliminating the risk of incorrect positioning during installation.

Sampling tube versions: plastic PST195 and aluminum ST280/ST580

The UG8-E-24 detector works with different types of sampling tubes:

Plastic tube PST195

• Supplied with the “stand-alone” version
• Made of PC/ABS material
• No cutting required – ready to use
• Designed for ducts with a diameter ≥ 200 mm; for ducts with a diameter < 200 mm, the UG-MB-8 mounting bracket must be used

Aluminum tubes ST280 and ST580

• Lengths of 280 mm and 580 mm respectively
• Can be cut to meet project requirements
• Mechanically and thermally resistant
• Compatible with the ST-EXTEND extension (1.06 m)

The option to select the appropriate tube type allows the installer to choose the solution best suited to the duct characteristics.

Functions and capabilities of the UG8-E detector

The Calectro UG8-E smoke detector uses optical detection of smoke particles in a measurement chamber through which air drawn directly from the ventilation duct flows. The entire detection and operating parameter monitoring process is automatic, and the device continuously analyzes both smoke levels and airflow conditions.

Optical detection – operating principle

At the heart of the device is an optical detector of type EVC-PY-DA / EVC-PR-DA, compliant with EN54-7. Inside the detection chamber, an LED and a photodetector are installed.

The operating principle is based on light scattering:

1. The LED emits a light beam inside the chamber.
2. Under normal conditions, the light does not reach the photodetector.
3. When smoke particles appear, they scatter the light, directing part of it toward the photodetector.
4. An increase in the light signal received by the photodetector triggers a smoke alarm.

This process allows the detection of even low particle concentrations, while the chamber design protects against false alarms caused by dust or external light.

The device is equipped with a set of functions that enhance safety and reduce maintenance requirements.

Automatic contamination compensation

The detector uses an electronic system that continuously monitors contamination levels and automatically adjusts the sensitivity to extend service life and prevent false alarms.

Service indication

When the detector reaches the compensation limit, the device activates a service alarm, indicated by a yellow LED. This clearly signals the need for cleaning or replacement of the detection head.

Electronic airflow monitoring

The UG8-E features airflow monitoring that signals:

• airflow that is too low,
• an incorrectly selected installation location,
• heavy contamination of the system.

In such cases, a yellow LED on the electronics board lights up and the relevant relays are deactivated.

Full set of alarm relays

The detector offers four relays that independently signal different operating states:

• 2 smoke alarm relays (NO/NC)
• service alarm and low airflow relay
• system fault relay

This solution facilitates integration with ventilation systems, BMS automation, and fire protection systems.

Installation of the UG8-E detector

The manufacturer recommends installation in a location where airflow is stable and representative—similar to the installation of airflow measuring devices.

If the detector is installed outdoors or in unheated spaces, the manufacturer requires the use of the UG-COVER-75 protective cover.

Detailed installation instructions, available in two versions for detectors with plastic and aluminum tubes, can be found on our website in the product download section.

Technical specifications of the UG8-E

• Power supply: 24 V AC/DC ±10% or (230 V AC ±10% for the UG8-E-230 version)
• Detection sensitivity: optical detector EVC-PY-DA / EVC-PR-DA (depending on power supply version)
• Current consumption: 85 mA DC, 235 mA AC
• Operating temperature: –20°C to +55°C
• Humidity: up to 95% RH
• Air velocity: 1–20 m/s
• Protection rating: IP65
• Housing: PC/ABS
• Certifications: CE, EN54-7, EN54-27

Applications of the UG8-E detector

The UG8-E is suitable for installations such as:

• ventilation and air conditioning systems,
• air handling units and mixing chambers,
• smoke extraction systems,
• fire protection systems,
• industrial installations requiring reliable smoke monitoring.

Thanks to its alarm relays, it can control fire dampers, shut down fans, or generate signals for higher-level systems.

Summary

The Calectro UG8-E-24 is an advanced smoke detector designed for detecting smoke in ventilation ducts. It combines high sensitivity, automatic contamination compensation, and easy installation. The availability of two tube types—plastic and aluminum—allows the device to be adapted to various HVAC installations.

With its robust design, high ingress protection rating, and a full set of signaling relays, the detector is one of the most versatile solutions in its category. It effectively supports fire safety and ensures the reliability of ventilation systems in buildings.