Gas Alarm GX-A1+

The Universal Gas Alarm Control Unit for Surface Mounting: Evaluation Unit for External Gas Sensors with Plain-Text Display, Two Relay Outputs and 48-Hour Relay Release

The Schabus GAS ALARM GX-A1+ is the control unit for a wide range of gas sensors and is used for professional gas monitoring indoors. It is the evaluation unit for an external gas sensor and already warns at a gas concentration that is far below life-threatening values. Depending on the connected sensor type, it monitors natural, town and liquid gases such as methane, propane, butane and ethanol, carbon dioxide (CO₂) as well as refrigerants such as R32, R404a or R410a.

The GX-A1+ supplies the sensor with operating voltage, controls the heating current if required and continuously evaluates the sensor voltage. In the event of an alarm it warns acoustically with a loud piezo signal generator and optically with flashing display illumination. At the same time a potential-free change-over relay switches, with which you can control for example a magnetic shut-off valve, a gas boiler or a ventilation system. A second relay reports technical faults that the device itself detects.

The sensor can be optimally positioned independently of the mounting height of the control unit. The GX-A1+ is the 100 % compatible successor to the GX-A1 with identical connection positions and replaces it in existing installations without rewiring.

Detect, Warn, Shut Off

The GX-A1+ combines flexible sensor selection with clear alarming, an informative display and potential-free relay outputs.

What's in the Box

The device has no options and no additional variants. Sensors are ordered separately.

• Gas alarm control unit GX-A1+ (without sensor)
• Mounting material: 4 screws and 4 wall plugs for wall mounting
• Detailed operating instructions

The matching gas sensor is not included in the scope of delivery and must be selected separately depending on the gas type.

How the GX-A1+ Is Constructed

The device is housed in a light grey plastic enclosure with a removable front plate. At the front you see the display, indicators and buttons; inside are the connection terminals.

How the GX-A1+ Warns

The GX-A1+ evaluates the voltage supplied by the sensor. With passive sensors such as the GX-LNG the gas-sensitive tin oxide sits in a voltage divider whose partial voltage changes with the gas concentration. With active sensors such as the GX-CO2-30 a microcontroller generates this voltage.

Which Sensors Fit

For each gas type a suitable sensor must be used. Details on triggering and minimum concentration can be found in the operating instructions of the respective sensor. A current list of compatible sensors can be found on the manufacturer’s website, or you can obtain it from technical support.

This is a selection. For each sensor type a prescribed mounting height must be observed because gases have different properties. Take it from the operating instructions of the sensor used.

Mount Correctly, Connect, Commission

Installation must be carried out by a qualified specialist. Please observe the five safety rules.

Wall Mounting

1. Loosen the four housing screws at the corners of the cover shell and remove the cover shell. If necessary unplug the ribbon cable at the connector.
2. Fix the base shell to the wall with the enclosed mounting material. Choose the position so that the display is easy to read when standing.
3. Feed the connection cables firmly as surface wiring from below.
4. Insert the electronics and close the device.

Connections

• Sensor connection: +5 V (operating voltage), S (sensor input), M (ground), +24 V (operating voltage). A maximum of one sensor is possible
• Observe the colour coding of the sensor cable and the sensor specifications
• Relay connections per relay: G (common), Ö (normally closed), S (normally open)
• In monitoring mode the relay is energised: normally open contact closed, normally closed contact open
• In alarm or fault mode the relay drops out: normally open contact open, normally closed contact closed
• The maximum switching current of 5 A must not be exceeded

First Commissioning

1. When mains voltage is applied an electrical functional test starts, then the warm-up phase of approx. 3 minutes. The display shows “System: OK / Sensor: Preheat”.
2. As soon as the sensor has reached its operating temperature the display shows “Sensor: Ready”.
3. After a power failure the test and warm-up phase are also restarted.
4. If no sensor is connected or the sensor is defective the display shows “System Error / Sensor Broken”, the yellow LED flashes and approx. every 30 seconds a short alarm tone sounds.

Functional Test of the Internal Systems

1. To protect your ears cover the sound opening of the piezo alarm generator with one hand and hold the “Reset | Test” button pressed.
2. After a few seconds delay each time the following happens in succession: The alarm tone sounds continuously, the green and yellow LEDs light, the red LED and the display illumination flash. Then the fault relay Re2 drops out, then the alarm relay Re1.
3. After releasing the button Re2 energises again immediately, LEDs, display and alarm generator return to the normal state, then Re1 also energises again.

This checks that all acoustic and optical alarms and the switching of the relays including delays work properly. If the test is started in the “Pre-Alarm” phase no alarm tone is heard. The connected sensor is not tested at the same time. How to test it is stated in the operating instructions of the sensor.

Mute Alarm, Service Pages, Sensor Failure

Mute Acoustic Alarm

During the main alarm a press of two seconds on “Reset | Test” only silences the acoustic alarm. The alarm relay remains dropped out and the optical warning remains. For the duration of the press the fault relay Re2 drops out briefly to inform the building management system and its recording of the acknowledgement.

The 15 Display Pages of the Service Button

• Main screen “System: OK / Sensor: Ready”
• Product Type: Series of the warning system
• Software Version
• On Time: total switch-on time
• Last Error Code: last error code
• Sensor Voltage: currently measured sensor voltage
• Voltage at Alarm: no function in this software version
• Error Counter: total counted errors
• Starts Counter: number of switch-on processes
• System Temp: operating temperature in the housing
• Chip Temp: temperature in the processor
• Last Error @: how long there has been no error
• Max Chip Temp: maximum processor temperature
• Max System Temp: maximum housing temperature
• Alarm Count ext: total counted alarms

For some counters a number is often already present because every device is tested before delivery. Keep the information from the service pages ready when you call technical support.

Sensor Failure: 48 Hours Time for Replacement

Sensors have a limited service life. So that for example a heating system can continue to run even without a sensor, press the “Service” and “Reset | Test” buttons simultaneously for at least 5 seconds until the display shows “Sensor Broken”. The fault relay Re2 remains dropped out and the alarm tone continues to sound every 30 seconds. The alarm relay Re1, however, energises again so that a device connected to it can continue to run for 48 hours. The lower display line shows the countdown, for example “Broken48”. During this time you replace the sensor.

Control External Devices

The two potential-free change-over relays switch on alarm or on fault. When connecting accessory devices, observe that the maximum switching current of 5 A must not be exceeded.

• Relay Re1 “Alarm”: switches on main alarm
• Relay Re2 “Fault”: switches on technical faults that the device itself detects
• Shut-off of a gas boiler
• Magnetic shut-off valve in the gas supply line
• Signal horn or warning light
• Ventilation system
• Building management system and home automation
• Telephone dialler and bus interface modules

Where the GX-A1+ May Be Used

• Only in dry indoor rooms of residential buildings and rooms with residential-like use
• Residential buildings and areas such as houses, apartments and rooms
• Sales areas such as shops and hypermarkets, rooms of the catering trade, small breweries and wine cellars
• Rooms of small businesses such as workshops, service centres and public authorities
• Technical rooms, areas with CO₂ cylinders, dispensing systems and dry ice storage
• Read the operating instructions thoroughly before installation and commissioning and keep them
• Packaging material is not a children’s toy and does not belong in children’s hands
• The manufacturer is not liable for damage or losses arising from the fact that no alarm signal is given despite an elevated gas concentration

What the GX-A1+ Does Not Do

• It only works with a connected sensor. Without a sensor it cannot detect any gas
• A maximum of one sensor can be connected
• It is not approved for potentially explosive atmospheres
• The protection class of the standard device is IP 20, for dry indoor rooms. A version in IP 65 is possible on request; please enquire with the manufacturer before ordering
• It does not switch systems off by itself. Solenoid valve or gas boiler must be connected via the relay
• The functional test only checks the internal systems, not the sensor
• The maintenance cycle depends on the connected sensor and the ambient conditions
• For carbon monoxide there are separate, specialised gas warning devices of the GX-C300 series

Detect and Classify Errors

In the event of a fault the fault relay Re2 drops out and the yellow LED “Error” flashes or lights. Press the Service button until the display shows “Last Error” with a number, and give this number to technical support.

Clean and Find Faults

Clean and Maintain

• Keep moisture (splash or rain water), dust and direct sunlight away from the device
• Clean the device only with a dry linen cloth; in case of heavy soiling it may be slightly dampened
• Do not use solvent-containing cleaning agents
• Check the sensor regularly in accordance with its operating instructions

Troubleshooting

If the fault persists, contact the manufacturer and keep the information from the service pages ready.

In Case of Service and Return

1. Get in touch if the device is defective and state your complete address as well as the reason for return.
2. Within Germany the manufacturer will send you a free return label by e-mail.
3. Pack the device adequately. Enclose a fault description, proof of purchase as well as your address and delivery address (name, telephone number, street, house number, postcode, city, country).

The manufacturer cannot accept unfree parcels. Unauthorised returns that do not constitute a complaint will be charged subsequently. The manufacturer accepts no liability for damage or loss during shipping.

Warranty, Guarantee and Disposal

The GX-A1+ is covered by the statutory warranty of at least 2 years in the EU. In the event of material defects and quality deficiencies the manufacturer repairs or replaces the device free of charge provided it has been used in accordance with the operating instructions. The manufacturer is not liable for damage due to accident, misuse, alteration or negligence. In addition, Elektrotechnik Schabus 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 device bears the CE marking. The CE declaration, the operating instructions and the mounting drawing can be found on the manufacturer’s website.

The GX-A1+ does not belong in household waste. The crossed-out waste bin symbol on the product reminds you to use the take-back systems so that the materials can be reused in an environmentally friendly manner at the end of the service life (WEEE Reg. No. DE91394868). Further information is available from the waste advice centre of your city or from the manufacturer.

Why the GX-A1+ Is Suitable

Application Areas

• Gas boilers and gas cookers in apartments and houses
• Technical rooms with gas connection
• Catering, dispensing systems and breweries
• Monitoring of CO₂ cylinders and water carbonators
• Cold rooms and rooms with dry ice storage
• Air conditioning systems, cold stores and heat pumps with refrigerant
• Workshops, service centres and public authorities
• Room air monitoring in offices, classrooms and event rooms

The Schabus GAS ALARM GX-A1+: Invisible gas, visible safety.

Frequently Asked Questions