Carbon Monoxide enters the sensor through a gas diffusion hole. A Graphite filter prevents any external contaminants from entering. A Platinum sensing electrode catalyses the oxidation of the CO. Combining with the water present in the electrolyte, this reaction causes the voltage to rise. Consequently, a small current flows between the two electrodes. This output is directly proportional to the amount of CO gas present. The microchip in the unit activates the horn/LED/display to give a warning applicable to the CO level sensed.

BS EN 50292 the code of practice for the selection, installation, use and maintenance of domestic CO alarms, recommends the following location for CO Alarms:

• Install a CO Alarm in all rooms where there is a fuel burning appliance
• If there is more than one appliance, but only one CO Alarm is to be installed,
)))the following priority list is recommended:

1. Rooms containing a flue-less, or an open-flue appliance
2. Rooms where occupants spend most time
3. Rooms where the appliance is most used
4. If the dwelling is a bed sit the CO alarm should be positioned away from appliance,
))))but close to the sleeping area

CO Alarms should not be located:

• In an enclosed space e.g. a cupboard
• Where it can be obstructed
• Directly above a sink
• Next to a door or window
• Next to an extractor fan or vent
• Where dirt & dust may block the sensor
• In a damp or humid location
• In the immediate vicinity of a cooking appliance

When only one CO Alarm is to be fitted, audibility of the sounder may be a problem in other areas of the property.

Where should CO Alarms be positioned?

CEILING MOUNTING
Preferred position in rooms containing a fuel
burning appliance

• 1-3m horizontally from the appliance
• At least 300mm from any wall and obstructions (e.g. light fitting)

Wall Mounting Option

• 1-3m horizontally from appliance
• 150mm vertically down from ceiling
• Above the height of any doors or windows