Boiler flues and accessories


Baxi Multifit flues Installed after 1st September 2021 are now UV resistant and can be run outside. Please download the attached addendum that will be added to all boilers for guidance on how the flue can be installed externally.

Multifit flue kits now come with positive screw fixings for all connections and are available in a choice of lengths to reduce the need for onsite cutting. By popular demand we offer a choice of colours for the terminals to match existing rainwater systems. 

  • Choice of flue options - flexibility for installers to, for example, work round an awkward flue truss or site a boiler discreetly, rather than it having to be on an outside wall
  • The telescopic flue kit provides a length of 350 – 500 mm, and flue lengths are available in 0.25 metre , 0.5 metre and 1 metre - hardly ever the need to cut a length of flue, reducing installation time and wastage
  • The flue sections are joined using a simple push seal mechanism with two positive screw connections - reassurance that the joint will not come apart
  • Potential distance of up to 10 metres maximum equivalent length for 60/100 vertical or horizontal concentric flues and 20 metres maximum equivalent length for 80/125 vertical or horizontal concentric flues
  • Calculating the equivalent flue length is simple: the first bend is ‘free’ then a one metre reduction for each 90 degree bend and half a metre reduction for each 45 degree bend
  • White, black and brown terminal options available - to better blend into the building
  • Plume management kit in black or white - can be retrofitted to the flue terminal and is competitively priced and easy to fit
  • Flues come as a complete kit in a box providing two wall support brackets for every metre of flue, silicone grease and fixings – complies with BS5440 

Domestic boiler flue regulations

The boiler flue position regulations are given in BS 5440 Part 1 for the UK and in I.S. 813 Domestic Gas Installations for Republic of Ireland. 

When siting the flue terminal, you should consider the plume of water vapour that will be discharged from the flue and install it so it will not cause a nuisance. 

Download our flue solutions guide

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