Flue Dilution

A flue dilution system is normally installed where difficulties are encountered in the provision of a conventional flue to above roof level. 

Flue dilution is only permitted for VLS (very low sulphur, i.e. <0.04%) fuels up to a total combined gross heat input rating 5.45MW nett heat input or 6MW gross heat input. However, regulations recommend flue dilution systems are not installed on systems with a combined net heat input greater than 2MW. 

These systems are designed on the principle of diluting the vented products of combustion sufficiently to reduce the CO2 content to the required level of below one per cent.  Fresh air and products of combustion from the boilers are drawn into a duct by a fan and consequently diluted, thus maintaining the low CO2 discharge levels, enabling safe discharge at low level. We also provide design advice on noise and plume reduction methods. 

We carefully design each system ensuring compliance with the Clean Air Act and Environmental Health Noise Control requirements.

Interested in this product?
Give us a call on
Email on

Case Studies

Installation of a Pentagon Mast Structure and Flue Systems

University of Warwick was in the process of making significant changes to its campus which required the University to increase the discharge heig...

University of Warwick
Supply, design and installation of Boiler and CHP flue systems

Construction of the Zayed Centre for Research into Rare Disease in Children began in 2015. The new centre will be the world's first purpose bu...

Great Ormond Street Hospital, ZCR