Division 3 Calculation method
United Kingdom
The methodology for calculating the energy efficiency of a specific fan is based on the ratio of gas power to electrical input power to the motor, where fan gas power is the product of gas volume flow rate and pressure difference across the fan. The pressure is either the static pressure or the total pressure, which is the sum of static and dynamic pressure depending upon the measurement and efficiency category.
- 3.1Where the fan is supplied as a ‘final assembly’, measure the gas power and the electric input power of the fan at its optimum energy efficiency point:
- 3.2Where the fan is supplied as ‘not final assembly’, the fan overall efficiency is calculated at the impeller’s optimum energy efficiency point, using the following equation:
- 3.3The fan gas power, Pu(s) (kW), is calculated according to the measurement category test method chosen by the fan supplier: