Ventilation changes within the Gas Industry Unsafe Situations Procedure (4th Edition)

To operate safely, all gas appliances need an adequate supply of air. In particular, gas appliances of the open-flue type require an adequate supply of air to ensure complete combustion of the gas and efficient operation of the flue to remove the combustion products. The air supply is provided by fixed ventilation openings, e.g. air bricks/grills, to the standards outlined in BS 5440 Part 2. ¹

Since April 1998, CORGI has provided guidance to their members on how to deal with a wide range of unsafe situations. This guidance, the Gas Industry Unsafe Situations Procedure, is compiled by a panel of experts from across the gas industry, and HSE is represented. This Procedure has always addressed situations where the supply of combustion air is inadequate, but there were concerns that the advice was ambiguous. Therefore, the Council For Registered Gas Installers’ (CORGI’s) advice to installers was changed in the 4th edition of the Procedure, specifically on how to deal with a situation where the supply of combustion air is found to be inadequate.

This part of the Procedure was revised in May 2005, and the advice to installers is now as follows:

• Any existing gas appliances with below 40 per cent, (0% to 39%), ventilation should be deemed as " At Risk" and the appliance should be turned off and the customer notified that the appliance should not be used until the defect has been rectified. This came into effect on 1 August 2005. (An “ At Risk” appliance is defined as one where one or more recognised faults exist, and which, as a result, if operated, may in the future constitute a danger to life or property).
• Appliances installed in a compartment and provided with less than 90 per cent ventilation should also be classified as "At Risk". There are particular dangers associated with this type of appliance if not installed correctly, as they can generate high levels of carbon monoxide in a very short period of time. Again this came into effect on 1 August 2005.
• From the 1 June 2008, all installations providing less than 90 per cent ventilation will be regarded as putting consumers "At Risk".

The industry decided to adopt this pragmatic two-stage approach in recognition of the difficulties for customers that could have been caused in applying the “At Risk” category to all relevant appliances straight away. The delay was designed to give both installers and customers the opportunity to act on the guidance without the inconvenience of appliances being turned off. In many cases, increasing the size of the airbrick, or removing obstructions, such as a fly screen, can resolve the situation. Of the approximate 45 million gas appliances in use in the UK, it is thought that only 500,000 – 1 million might be affected by this change.

HSE would expect any gas installer who encounters an appliance that fits into one of the above categories, to act on the guidance contained in the CORGI Unsafe Situations Procedure.

The regulations, and an associated Approved Code of Practice, place requirements on all gas installers to carry out certain specified safety checks immediately after performing any work on a gas appliance. Such work would include routine servicing.

One of the specified checks is to ensure an adequate supply of combustion air. The assessment should take into account a range of factors, and an Appendix to the Approved Code gives further advice. Installers are told to refer to appropriate standards.

Further guidance can be found within the Gas Industry Unsafe Situations Procedure (4th Edition) available from the Council for Registered Gas Installers, 1 Elmwood, Chineham Park, Crockford Lane, Basingstoke, Hants, RG24 8WG Tel – 0870 401 2200 or www.corgi-gas-safety.com.

Footnotes

1. BS 5440 Part 2:2000 “Installation and maintenance of flues and ventilation for gas appliances of rated input not exceeding 70KW net (1 st, 2 nd and 3 rd family gases). Specification for installation and maintenance of ventilation for gas appliances.