Safe as well as warm

Rex Taylor of Kidde Safety Europe offers a reminder of the legal requirements for carbon monoxide alarms when installing fireplaces and heating appliances.

Carbon monoxide (CO) is odourless and colourless, but deadly. It can be produced by any fuel burning appliance, from the incomplete combustion of carbon-based fuels such as bottled or mains gas, coal and wood – including open fires and wood burning stoves.

With fixed appliances, problems often occur with blockages and back-drafts in flues or loose, blocked or inappropriate vent pipes. In some cases, these have been caused by building work or interference with flues in shared roof spaces. Indications of problems include slow burning or extinguished solid fuel appliances. Although not a replacement for regular servicing and chimney sweeping, working CO alarms in homes are essential in curbing this silent killer.

Building regulation requirements

Various, differing Building Regulations throughout the UK now require CO alarms – but only with installation of new or replacement fixed combustion appliances. Unlike most Building Regulations, they are not necessarily related to new buildings and can also apply to existing buildings, where the only work is fitting an appliance.

The Regulations themselves are non-specific. For example, Building Regulation J3 (applying to England and Wales) states simply that: “Where a fixed combustion appliance is provided, appropriate provision shall be made to detect and give warning of the release of carbon monoxide.” But Approved Document J only requires a CO alarm in the same room as a new or replacement fixed solid fuel appliance (with a rated output up to 50 kW).

In Northern Ireland, the 2012 Technical Booklet L applies to new and replacement combustion appliances (not solely for cooking) in all homes and irrespective of fuel or flue type. A CO alarm must be fitted in the same room as the combustion appliance or just outside boiler rooms. Scotland has similar requirements in its Technical Handbooks but, in addition, an alarm is required in any bedroom or principal living room containing a flue. These requirements now also apply to all private rented housing with combustion appliances in Scotland.

A wider approach is taken by BS EN 50292:2013. This standard applies to any domestic property, whether existing or new, rented or owner-occupied. In the standard, recommendations for CO alarms relate only to combustion appliances within the property being considered. However, CO cannot be contained within a single property and might spread unnoticed to adjacent properties which may not have a combustion appliance. There is therefore a compelling case for CO alarms in all homes to give peace of mind.

Obviously it is essential that carbon monoxide from the source reaches the CO alarm to trigger it, and also that occupants are alerted or woken by alarm sounders. BS EN 50292:2013 recommends that ideally, a CO alarm should be installed in every room containing a fuel-burning appliance (or outside boiler rooms) and in other areas to give warning such as well-used remote rooms and all bedrooms. If this is not viable, CO alarms should be considered in any room containing a flue-less or open-flue appliance and where the occupants spend most time – notably, living rooms with fireplaces.

Recent research shows that CO is normally emitted warm and so will tend to flow upwards, determining best locations as upper wall level or ceilings, as shown in the diagram. According to all the Regulations and BS EN 50292:2013, alarms can be powered either by mains or batteries designed for the whole working life of the alarm. Mains alarms are increasingly being installed alongside hard-wired smoke and heat alarms, sometimes offering extra safety features.

Interconnecting alarms

Hard-wired CO alarms can interlink with each other so that they all sound when one is triggered, but they can also interconnect with smoke and heat alarms. Here, all the alarms can act as sounders to alert of either risk, forming comprehensive systems. Crucially, the alarms must have different, distinct alarm sounder patterns for carbon monoxide and fire. This allows occupants to respond quickly, as very different reactions are required for fire and carbon monoxide.

Finally, it is worth remembering the additional fire risk presented by open fires and stoves, and the essential early warning offered by smoke alarms. Here, current Building Regulation guidance requirements are based on the Code of Practice BS 5839-6:2013, which applies to all types of housing, whether new or existing.

In the Code, the number and locations of alarms are defined by ‘Category’ and the minimum recommended, applicable to most properties with up to three storeys and no single floor over 200 m2, is Category LD2 – essentially alarms in circulation areas, living rooms and kitchens. Building Regulation guidance in Scotland and Northern Ireland generally mirror the Code with Category LD2. But in England and Wales, Approved Document B only requires Category LD3 with smoke alarms in escape routes.

Yet, as the Code says, in Category LD3 the evacuation time once fire is detected in the escape route “might not prevent death or serious injury of occupants of the room where fire originates”. Responsible housebuilders might choose to go beyond Approved Document B and add interconnected smoke alarms in living rooms too, particularly those with fireplaces.

Rex Taylor is technical support manager of Kidde Safety Europe