Appliance Efficiencies

The minimum appliance efficiencies quoted below are measured at normal rated output and are on a Gross CV basis. They are not seasonal efficiencies. The majority of appliances listed in the HETAS Guide have efficiencies well above these minimum, pass mark, values. There is also evidence to show that with solid fuel appliances efficiency does not fall off greatly as the output of the appliance reduces. Additional useful heat, which is not included in these minimum values, can be available from the chimney and fireplace particularly if the chimney is centrally placed and enclosed in the building structure.

Testing has, until recently, been carried out to British Standards (BSS) using an appropriate standard test fuel. It is against these earlier BSS that most of the appliances listed in this Guide have been tested. After 1 January 2003 Type Testing is now carried out to the relevant BS ENs. These new European Standards now adopted as British Standards are as follows:- Independent boilers BS EN 12809; or when wood pellets fired to BS EN 14785 or BS EN 303-5; Cookers BS EN 12815; Roomheaters BS EN 13240; or when wood pellets fired to BS EN 14785; Open Fires BS EN 13229.

The standard test fuels used are representative of those DEFRA Authorised Fuels which can be used in Smoke Control Areas (SCAs). Bituminous Housecoal, Wood Logs and Wood Pellets are not permitted to be used in SCAs unless they are burned in specially designed, smoke reducing, DEFRA Exempted Appliances. The minimum efficiency pass values that are listed below are under review with the intent of raising them further. Click below to download more information on minimum efficiency levels.

Heating Appliance Minimum

Efficiency Levels (pdf)