Installation & Operation Manual Merlin Gas Detector
Rev: 18 03-20
5
Wiring the Detector
Building Management Systems (BMS)
If you are connecting to Merlin ‘S’ range you will need to use [NC/COM] terminals as an alarm
relay. These are volt free connections to building management systems.
If you are using our ‘GDP’ range you will need to use the [C/L] terminal as an alarm relay.
A relay will change state when in alarm or when gas is detected.
BMS terminals can be used in conjunction with other external relays that affect other devices
and controls such as purge fans and audible alarms etc.
Audible Alarm Switch
There is a switch on the Detector circuit board.
The user can choose whether to have an audible alarm when dangerous gas levels are
detected. The alarm will continuously sound – there are no provisions to silence the alarm, gas
levels must drop to a safe value for the alarm to stop.
The buzzer measures approx. 65 dB from a distance of 300mm/1ft (tested in quiet conditions).
Testing the system
There is a [TEST] button on the Detector circuit board.
When the test button is pressed and held for 3 seconds – the detector will simulate an open
circuit to ensure alarms (low and then high), and other external devices connected operate as
intended in the event of a gas leak.
It is recommended testing your detectors with a calibrated gas. Contact your supplier.
