What is a Flue Dilution Fan?

By Kira Jopp on Thu 02 July 2020

What is a Flue Dilution Fan?

A flue dilution fan enables companies to disperse emissions created during the combustion process at low levels and comply with the Clean Air Act 1993 and the Gas Engineers UPE 10/Part 1 (issue 3) Regulations. These regulations dictate that the CO2 content of emissions released at low levels must be below 1%. Airflow’s flue dilution fans work by introducing fresh air into the discharge flue duct from the boiler and diluting the gases to below the 1% threshold.

High quality flue dilution fans come with a differential pressure safety switch, which turns the boiler off in the event of fan failure or a blocked flue.

Flue dilution fans are suitable for atmospheric and condensing type boilers.


What type of Flue Dilution fan is right for me?

To guarantee a maximum of 1% CO2 content in the exhaust gases all that is needed is 2m of flue ducting from the fan to the outlet.

Please note that if LPG or Butane are being used then care should be taken as air flow rate are increased. Furthermore, flow rate provided by the fan will depend on the static pressure of the ducting system.


Why would I use a Flue Dilution fan?

You would use a flue dilution fan when it’s not possible to have a tall flue chimney built on site. By using a flue dilution fan over a flue chimney, you are able to significantly reduce construction costs of the site as well as reduce the conspicuousness of the building.

A quick guide to what size unit you'll need for your boiler size:












 Maximum Boiler Input Rating KW 80 160 270 425 650