What is BS 4856-3 – Performance of heating and cooling units about? 
BS 4856 is a European Standard that discusses methods for testing and rating of fan coil units, unit heaters and unit coolers.
BS 4856-3 is the third part of the BS 4856 series, which deals with methods of carrying out thermal and volumetric tests on units intended for use with additional ducting containing fluid to air heat exchangers and incorporating their own electrically powered fan system.
The main objective of the BS 4856-3 is to provide the best industry methods to determine the thermal and volumetric performance of fan heating and cooling duties and to ensure they are reliable and effective for use.
Who is BS 4856-3 - Performance of heating and cooling units for?  
BS 4856-3 on thermal and volumetric performance of heating and cooling duties is relevant to:  
- Manufacturers of components of ventilation and air conditioning systems
- Manufacturers of fan coil units, unit heaters and unit coolers
- Quality control and testing personnel 
- Mechanical engineers 
- Product designers 
Why should you use BS 4856-3 - Performance of heating and cooling units?  
The rating tests described in BS 4856-3 are for heating units with the fan located upstream of the coil, and for cooling units with the fan in any position.
BS 4856-3 provides best industry operating conditions of the units.
The object of the tests is to establish the performance of the unit over a specified range of primary and secondary fluid conditions and room temperatures. The test procedures set out in BS 4856-3 are for the determination of:
- The gross and net thermal outputs
- The secondary fluid flow rates
- The primary fluid pressure drop
- Freedom from sweating on the unit enclosure or casework
- Adequate condensate disposal
If you are a manufacturer of fan coil units, unit heaters and unit coolers, by adopting BS 4856-3-compliant testing and rating methods, you can determine whether your products are fit for its intended use. As a result, you can identify and correct the source of thermal and volumetric imbalances in fan coil units, unit heaters and unit coolers, such that their operational and functional efficiency remains uncompromised.
