Description

This British Standard describes a procedure for assessing the thermal performance of low temperature hot water boilers, which are intended for central heating or indirect hot water supply and which are fired with solid, liquid or gaseous fuels.

The thermal efficiency is obtained by the direct method of test and is established to within a tolerance of ± 2 % points2). Flue gas losses and loss due to combustibles in ash, where applicable, are determined by measurement. Surface heat losses and other unmeasured losses are derived by difference. Procedures are also included to determine the associated characteristics of water-side resistance and gas-side resistance.

This standard applies to boilers designed to operate at flow temperatures not exceeding 100 °C, with rated heat output between 44 kW and 600 kW when used with one or more of the following fuels:

• a) smokeless solid fuels, e.g. coke or anthracite, fired by means of automatic combustion appliances;
  
• b) bituminous coal fired by means of mechanical stokers;
  
• c) gaseous fuels of the 2nd and 3rd families (see BS 4947);
  

and with rated heat output between 300 kW and 600 kW when used with liquid fuels of the classes specified in BS 2869.

Scope

This Standard does not apply to steam boilers or to boilers pressurized by steam.