CO Alarm GX-C300 Carbon Monoxide Detector
€251.26
The professional CO detector with ppm-accurate display and two relays for shutdown, ventilation and building management systems
The Schabus PROFI CO ALARM GX-C300 is a fixed-installation carbon monoxide detector with an integrated electrochemical sensor. It monitors combustion appliances and gas boilers for escaping carbon monoxide (CO) and displays the measured CO concentration with ppm accuracy on an illuminated plain-text display. In the event of danger it warns acoustically with a loud piezo signal tone and optically with flashing display illumination and a red LED. At the same time the alarm relay drops out and switches off the hazard source, for example via a solenoid shut-off valve in the gas supply line, so that no further CO can escape if the gas boiler is defective.
The GX-C300 is the base model of the C series. It has two potential-free changeover relays: the alarm relay activates ventilation systems, shut-off valves or external signalling equipment; the fault relay reports faults detected by the device itself, for example to the building management system or home automation. This makes it suitable for boiler rooms, technical rooms, commercial installations and residential-adjacent areas, including stairwells and escape routes, small private underground garages, canteens and mobile kitchens.
Sensor, measuring cell, evaluation electronics and software have undergone a full test by TÜV Süd according to DIN EN 50291 (with exceptions, see operating instructions). The alarm characteristic is graduated: at high CO levels the alarm is triggered quickly; at lower concentrations it is delayed in accordance with the standard. This avoids false alarms while still detecting gradual poisoning. The alarm thresholds can be factory-programmed according to your specifications. The GX-C300 operates from the mains without a battery, is maintenance-free and designed for continuous operation over many years.
Important note: The GX-C300 may only be installed on a wall in dry indoor rooms, not in potentially explosive atmospheres. Installation and mains connection must be carried out by a qualified specialist. Choose the mounting position so that the display is easy to read when standing.
Measure, display, warn, switch
The GX-C300 combines standards-compliant CO detection with a plain-text display and two potential-free relays for active protective measures.
Standards-compliant CO detection
Electrochemical sensor, TÜV-tested according to DIN EN 50291 with graduated alarm characteristic and intelligent delay to prevent false alarms.
ppm-accurate display
The illuminated plain-text display shows the operating status and the measured CO concentration in the room air. The display is in English plain text.
Acoustic and visual
Loud piezo sounder, flashing display illumination and red LED provide unmistakable warning.
Alarm relay
Potential-free changeover contact for switching off the hazard source, e.g. with a solenoid shut-off valve, or for activating ventilation and signalling equipment.
Fault relay
Potential-free changeover contact that reports faults to the building management system or home automation.
Factory-programmable
The alarm thresholds can be factory-programmed according to your specifications.
Intelligent self-monitoring
A 32-bit microcontroller continuously monitors the system at approximately 300 points. The sensor element is tested in the background every 24 hours.
Test button
With the RESET | TEST button you check the acoustic alarm sounder, the LEDs and the relays.
Mains operation without battery
Integrated switched-mode power supply for low power consumption; no battery required.
Replaceable sensor
When the sensor reaches the end of its service life, the cover is fitted with a new sensor at the factory and recalibrated.
What is included in the box
Everything needed for wall mounting is included. The device has no options and no additional variants.
- CO alarm device GX-C300
- Mounting material (4 screws + wall plugs)
- Operating instructions
How the GX-C300 is constructed
The GX-C300 is a wall-mounted device in a housing consisting of a base and front panel. Sensor, evaluation electronics, display, sounder and relays are combined in one unit; an external sensor is not required.
Housing with base and front panel
The front panel is held by four housing screws. For wall mounting the screws are loosened and the front panel removed; if necessary the flat ribbon cable is unplugged. The base is then mounted on the wall using the supplied mounting material. Cable entries with PG cable glands are located on the underside.
Plain-text display
The illuminated display continuously informs about the operating status and the measured CO concentration. After applying mains voltage it greets you with the manufacturer name and device type, then the main display “CO : Ready” appears. In the event of an alarm the display illumination flashes.
SERVICE and RESET | TEST buttons
With the SERVICE button you scroll through the information displays and, in the event of a fault, retrieve the error number. With the RESET | TEST button you check the alarm sounder, acknowledge the acoustic alarm and reset the fault relay.
Status indicators (LEDs)
Three LEDs indicate the status: OPERATE (green) for operation, ERROR (yellow) for faults and ALARM (red) for alarm. If only the green LED lights after switch-on, the device is ready for operation.
Piezo sounder
The sounder emits a loud, penetrating tone in the event of an alarm. In the event of a fault a short beep sounds every 10 seconds.
Internal electrochemical CO sensor
The sensor is located inside the device and measures carbon monoxide directly in the room air. It contains chemically pure water that reacts with the CO molecules. The cooler and more humid the environment, the longer the sensor lasts. When the water has evaporated, the sensor self-test detects this and reports a non-rectifiable fault. The cover is then fitted with a new sensor at the factory and recalibrated.
Two potential-free changeover relays
The alarm relay Re1 (left) switches in the event of an alarm; the fault relay Re2 (right) switches in the event of faults. Each relay has the terminals G (common contact), Ö (normally closed) and S (normally open). In monitoring mode the relays are energised; in alarm or fault mode they drop out. The permissible switching load of the relays must never be exceeded according to the operating instructions.
Mains connection and terminal blocks
After opening the housing the safety cover (High Voltage) is removed. The mains cable is routed through the PG cable gland and connected to the screw terminals L, N and PE. These are each provided in duplicate and interconnected to facilitate bridging to the relays.
Installing and commissioning
Before installation and first commissioning, carefully read the operating instructions and follow the safety instructions in particular. Installation must be carried out by a qualified specialist who also observes the five safety rules.
Mounting position
At breathing height
The device is mounted on a wall at breathing height, where CO is inhaled.
Display readable when standing
Choose the position so that the display is easy to read when standing. This ensures the proper functioning of the warning device.
Dry indoor rooms only
Install only on a wall in dry indoor rooms, not in potentially explosive atmospheres.
Commissioning
- Loosen the housing screws, remove the front panel and fasten the base to the wall with the supplied mounting material.
- Install the connecting cables leading to the device as fixed surface-mounted cables.
- Remove the safety cover (High Voltage) and connect the mains cable to terminals L, N and PE. If required, connect the potential-free relays for shut-off valve, ventilation or building management system.
- Refit the front panel (do not forget the flat ribbon cable) and screw it in place.
- Apply mains voltage. The device performs a short electrical function test; the display shows the manufacturer name and device type. If the green LED then lights alone, the device is ready for operation.
After a power failure: Even after a brief power failure the function test is restarted. The warning system then monitors the room again without restrictions.
How the GX-C300 reacts and how you check it
DIN EN 50291 specifies alarm delay times depending on the gas concentration: the higher the CO concentration, the faster the alarm is triggered. When the 300 ppm threshold is reached the system alarms immediately – hence the type designation GX-C300.
What happens in the event of an alarm
- When the alarm thresholds are reached the device warns with a loud, penetrating tone, flashing display illumination and red LED.
- At the same time the alarm relay Re1 drops out and switches, for example, a solenoid shut-off valve or a ventilation system.
- The display shows “Alarm” with the alarm level, e.g. “CO: Alarm 100”, and the exact value in the second line.
- Acknowledge the acoustic alarm with the RESET | TEST button.
- The alarm delay time starts again if the ventilation measures immediately initiated have not significantly reduced the CO concentration.
Behaviour in the event of an alarm
- Ventilate the room and ensure by switching off the CO source that no further carbon monoxide can escape
- Inform other persons and instruct them to leave the room
- Stay calm, open all doors and windows and take all combustion appliances out of service
- In the case of gas appliances, operate the emergency shut-off valve
- If the alarm continues or recurs, evacuate the building and leave all windows and doors open
- Ensure that all persons in the building have been warned
- Obtain medical help for anyone showing symptoms of carbon monoxide poisoning and point out that inhalation of carbon monoxide is suspected
- If necessary, call the emergency number so that the source of the CO leak can be identified and eliminated
- Do not put the combustion appliance back into service until it has been checked and released by a competent person
Function test
For your safety we recommend regularly checking the acoustic alarm sounder with the test button. All three LEDs light up and both relays Re1 and Re2 drop out. The correct operation of the sensor should be tested approximately every 3 months with suitable test gas.
Display below 30 ppm: The standard provides that no value is displayed in the low range so as not to alarm you unnecessarily. In the service menu there is a page that shows the exact value even below 30 ppm.
Display information, self-test and faults
Display information
Each press of the SERVICE button takes you to the next information display until the main display appears again. “CO Sensor” shows the ppm-accurate value; “Sensor Test @” shows how much time has elapsed since the last sensor test. If you remain on one display, the device returns to the main display by itself after a while. This also works if you hold the SERVICE button down for about 8 seconds.
Self-test
Built-in intelligence (32-bit microcontroller) continuously monitors the system at approximately 300 points inside the device. Temperatures, voltages and currents are measured and compensated, some are stored for internal long-term tests and some are shown on the display. Every 24 hours the system performs tests on the sensor element that run in the background. If a self-test is rated “not good”, the system restarts up to three times, repeats the measurements and then decides whether to issue a fault message.
Indication of a fault
In the event of any fault the fault relay Re2 drops out so that the building management system is informed. In addition the yellow LED flashes or lights continuously and a short beep sounds every 10 seconds. Press the SERVICE button until the display provides information about the type of fault. Under “Last Error” you will find a number that you can quote to Elektrotechnik Schabus technical support. Most faults do not affect the CO measurement. They may indicate adverse environmental conditions with accelerated ageing or mains voltage fluctuations. The flashing patterns of the yellow LED are controlled by the microcontroller. If it itself has a problem, the yellow LED lights continuously. This can only be remedied at the factory.
Error codes overview
| No. | Display indication | Meaning | Yellow LED |
|---|---|---|---|
| 1 | VDD_UNDERVOLTAGE | Internal supply voltage too low | – |
| 2 | SUPPLY_UNDERVOLTAGE | Mains supply too low | – |
| 3 | EXTERNAL_SENSOR_BROKEN | Sensor or sensor cable defective | – |
| 4 | LED_YELLOW_NOT_ON | Yellow LED cannot be switched on | – |
| 5 | LED_YELLOW_NOT_OFF | Yellow LED cannot be switched off | – |
| 6 | LED_RED_NOT_ON | Red LED cannot be switched on | – |
| 7 | LED_RED_NOT_OFF | Red LED cannot be switched off | – |
| 8 | LED_GREEN_NOT_ON | Green LED cannot be switched on | – |
| 9 | LED_GREEN_NOT_OFF | Green LED cannot be switched off | – |
| 10 | PWM_OUT_NOT_ON | Internal output fault | – |
| 11 | PWM_OUT_NOT_OFF | Internal output fault | – |
| 12 | EXTERNAL_SENSOR_BAD | Sensor test failed | – |
| 21 | NVMEM_INIT_FAILED | Memory initialisation failed | flashes slowly |
| 22 | MISSING_ERROR_CATEGORY | Internal software error | flashes slowly |
| 23 | ENVIROMENT_TOO_COLD | Ambient temperature too low | lights continuously |
| 24 | ENVIROMENT_TOO_HOT | Ambient temperature too high | lights continuously |
| 25 | SENSORTEST_FAILED | Sensor test failed | flashes rapidly |
| 26 | TEMP_SENSOR_ERROR | Temperature sensor error | flashes slowly |
| 27 | NVMEM_CHECKSUM_ERROR | Memory error detected | flashes slowly |
Clearing faults
Press the RESET | TEST button so that the fault relay Re2 re-energises. Only if a fault of the same or a different type occurs again will it drop out. Most faults clear themselves or when the warning device is disconnected from the power supply, allowed to cool for about 15 minutes and then restarted. If there is no improvement, contact Elektrotechnik Schabus technical support.
Manufacturer’s notes
- Carefully read and keep the operating instructions before installation and first commissioning
- Installation only by a qualified specialist
- Install only on a wall in dry indoor rooms, not in potentially explosive atmospheres
- Packaging material is not a toy and must be kept away from children
- Avoid moisture (splash or rain water), dust and direct sunlight
- Intended for residential areas, sales areas, commercial and industrial premises and small businesses connected to the public low-voltage network
- The device is not approved for other uses
- The CE declaration is available for download on the manufacturer’s website
Cleaning and care
The GX-C300 operates maintenance-free. Only occasionally remove dust with dry cloths; in case of heavy soiling the linen cloth may be slightly dampened. Do not use solvent-based cleaning agents. Do not vacuum the device with a vacuum cleaner: through the small slots and openings very high air velocities can arise inside that permanently impair the sensor element. A defect or a severely shortened service life would be the result.
Note for maintenance companies
It is recommended that at every visit all data are entered in a list with date and time. This allows conclusions to be drawn about the operational reliability of the system and any possible tampering. A template can be found in the operating instructions.
Warranty, guarantee and disposal
The GX-C300 is covered by the statutory warranty of at least 2 years in the EU. The manufacturer Elektrotechnik Schabus additionally offers a 5-year guarantee that can be registered online. Repair and spare parts are available directly from the manufacturer, even beyond the statutory warranty.
The GX-C300 must not be disposed of with household waste. The crossed-out wheeled bin symbol on the product reminds you to use the take-back systems for waste electrical and electronic equipment (WEEE No. DE91394868). Further information on collection, reuse and recycling systems is available from your local waste advice centre.
Why the GX-C300 is suitable
Active protection
Alarm relay switches shut-off valve, ventilation or signalling equipment in the event of an alarm.
Standards-compliant
TÜV-tested electrochemical sensor according to DIN EN 50291 with intelligent delay to prevent false alarms.
Always in view
ppm-accurate display on the illuminated plain-text display.
Unmistakable
Loud piezo tone, flashing display illumination and red LED.
For building management systems
Separate potential-free relays for alarm and fault.
Self-monitoring
Continuous monitoring at approximately 300 points and daily tests of the sensor element.
According to your specifications
Alarm thresholds factory-programmable.
From the manufacturer
Made in Germany, 5-year guarantee registerable, repair and spare parts directly from the manufacturer.
Areas of application
- Boiler rooms with gas boiler or heating boiler: shutdown in the event of flue gas backflow
- Technical and utility rooms with combustion appliances
- Commercial installations and industry with combustion processes
- Stairwells and escape routes
- Small private underground garages
- Canteens, catering and mobile kitchens with open fireplaces
- Shisha bars and smoking clubs
- Residential-adjacent areas and retrofitting in boiler rooms of private households
- Control of building management systems, home automation and ventilation systems
- All dry indoor rooms with combustion appliances
The Schabus PROFI CO ALARM GX-C300: CO detected, danger averted.
Frequently asked questions
What does the GX-C300 monitor?
The GX-C300 monitors carbon monoxide (CO) at combustion appliances and gas boilers, for example in boiler rooms, technical rooms, canteens and underground garages. The measured concentration is displayed with ppm accuracy on the display.
What happens in the event of an alarm?
The piezo sounder emits a loud tone, the display illumination and the red LED flash, and the alarm relay Re1 drops out. This allows, for example, a solenoid shut-off valve in the gas supply line to be switched or a ventilation system to be activated. Acknowledge the acoustic alarm with the RESET | TEST button.
Why does the alarm not trigger immediately at low CO levels?
The alarm characteristic is graduated as specified by DIN EN 50291: at high CO levels the alarm is triggered quickly; at lower concentrations it is delayed. This avoids false alarms while still detecting gradual poisoning. When the 300 ppm threshold is reached the system alarms immediately.
Can I adjust the alarm thresholds?
Yes, the alarm thresholds can be factory-programmed according to your specifications, for example for an immediate alarm at a lower threshold. Please contact us about this before ordering.
What are the two relays for?
Both are potential-free changeover relays. The alarm relay Re1 switches in the event of an alarm and activates, for example, ventilation, a shut-off valve or external signalling equipment. The fault relay Re2 reports faults detected by the device itself to the building management system or home automation.
Where do I install the GX-C300?
On a wall in a dry indoor room, at breathing height and so that the display is easy to read when standing. Not in potentially explosive atmospheres. Installation and mains connection must be carried out by a qualified specialist.
How do I recognise that the device is ready for operation?
After applying mains voltage a short function test runs; the display shows the manufacturer name and device type. If the green LED then lights alone and the display shows “CO : Ready”, the device is ready for operation.
Why does the display show no value below 30 ppm?
This is specified by the standard so as not to alarm you unnecessarily. In the service menu there is a page that shows you the exact value even below 30 ppm. You reach it with the SERVICE button.
How do I test the function?
With the RESET | TEST button you check the acoustic alarm sounder. All three LEDs light up and both relays drop out. The correct operation of the sensor should be tested approximately every 3 months with suitable test gas. In addition the device automatically performs tests on the sensor element every 24 hours.
What does the yellow LED mean?
The yellow LED indicates a fault detected by the device itself. The fault relay Re2 drops out and a short beep sounds every 10 seconds. You can find the type of fault via the SERVICE button under “Last Error”. If the yellow LED lights continuously, this may also indicate a problem with the microcontroller that can only be remedied at the factory.
What to do in the event of a fault?
Press the RESET | TEST button so that the fault relay re-energises. Most faults clear themselves or after the device has been disconnected from the power supply for about 15 minutes and allowed to cool. If there is no improvement, quote the number under “Last Error” to technical support.
What happens in the event of a power failure?
Even after a brief power failure the function test is restarted when mains voltage returns. The device then monitors the room again without restrictions.
How long does the sensor last?
This depends on the environment: the cooler and more humid it is, the longer the sensor lasts. When the water in the sensor has evaporated, the device reports a non-rectifiable fault. Then have the cover fitted with a new sensor and recalibrated at Elektrotechnik Schabus.
May I vacuum the device?
No. Remove dust only with dry cloths. When vacuuming, very high air velocities can arise inside that permanently impair the sensor element.
What to do in the event of a persistent or repeated alarm?
Evacuate the building, leave all windows and doors open and ensure that all persons have been warned. Obtain medical help for persons with poisoning symptoms and, if necessary, call the emergency number. Do not put the combustion appliance back into service until it has been checked and released by a competent person.
How long is the guarantee valid?
The statutory warranty of at least 2 years applies in the EU. In addition the manufacturer Schabus offers a 5-year guarantee that can be registered online.
Questions about the CO ALARM GX-C300?
Our support team in Germany advises you free of charge on selection, installation and configuration.
PROFI CO ALARM GX-C300 – Carbon Monoxide Detector
The GX-C300 is a professional CO warning system designed for precise monitoring of carbon monoxide in heating, technical, and occupied rooms. Featuring factory-calibrated electrochemical sensor technology, accurate ppm display, and a robust housing, the system provides reliable protection in safety-critical environments.
Technical Data
- Operating voltage: 100–240 V AC, 50–60 Hz
- Power consumption: approx. 2–8 VA (depending on operating state)
- Protection rating: IP54 (control unit), IP20 according to extension data
- Display: 2×16 character screen, ppm-accurate, English text, white/blue backlight
- CO concentration: measuring range 0–330 ppm, triggering according to standard
- Accuracy: < ±1 %, < ±2 ppm, factory calibrated
- Relay contacts: 2 changeover contacts NC/NO (potential-free)
- Service life: up to 10 years at max. 28 °C / min. 30 % RH; up to 6 years at max. 40 °C / min. 40 % RH
- Sound pressure level: 85 dB(A) @ 1 m, piezoelectric
- Dimensions (control unit H×W×D): 80 × 160 × 55 mm
Environmental Conditions
- Operating range (control unit): -15 °C to +45 °C, 10–90 % RH (non-condensing)
- Operating range (sensor): 0 °C to +60 °C, 10–90 % RH (non-condensing)
- Humidity: 10–90 % RH (non-condensing)
- Sensor supply voltage: +24 V DC
Sensor Technology
- Gas type: Carbon monoxide (CO)
- Measuring principle: Electrochemical internal sensor
- Software version: X0.82
- Sensor service life: up to 10 years at 28 °C / 30 % RH, up to 6 years at 40 °C / 40 % RH
Manufacturer information:
Electrical engineering Schabus GmbH & Co. KG
Baierbacher Straße 150
83071 Stephanskirchen
Germany
Telephone: +49 80 36 / 674 979 – 0
Email: info@elektrotechnik-schabus.de
Responsible person:
Didactum® Security GmbH
Im Mühlenfeld 4
48163 Münster
Deutschland
Fon:
(+49) 250 19 71 63 54 / (+49) 171 33 11 577
Email: info@didactum-security.de
