EZ-Fit Vertical conventional flues (Orange System)

Grant EZ-Fit Orange System - blackAs many older oil fired boilers are traditionally connected to conventional flue systems, updating to a modern condensing boiler often results in the appliance needing to be relocated. The Grant EZ–Fit Conventional flue system (Orange system) has been specifically designed to enable the existing chimney to be re-used and the boiler retained in its original position.

Flexi Packs

We have developed a range of EZ-Fit Flexi packs containing all the components required to utilise the existing chimney, including a smooth bore stainless steel flue liner, terminal, clamp plate and connectors for both the flex and boiler. All that is required to complete the installation is extension pipes or elbows from our Orange system accessories range. Please note: the flexi liner should be installed with the directional arrows pointing upwards only


Condensing boilers operate at extremely high efficiencies with cool flue gas temperatures, resulting in a plume of vapour being visible at the flue terminal. This pluming (steam) is a normal condition of condensing boilers and indicates that the appliance is working efficiently. As an alternative to a Low Level, High Level, or Vertical balanced flue kit, utilising the original chimney with a Grant conventional Flexi-pack moves the plume of vapour above roof level.


An adequate permanent air supply is required for the safe operation of all open-flued (conventional flued) oil-fired appliances. For new or replacement boilers in properties built prior to the latest change to the Building Regulations (pre Approved Document L1A 2006) in England and Wales this ventilation must be in accordance with BS5410: Part1:1997. For installations in properties built or refurbished under the above current Building Regulations, the first 5kW of output should no longer be omitted for the purposes of calculating the ventilation area required.


  • Suitable for Grant Vortex boilers up to 70kW
  • Maximum vertical height (from top of boiler) = 19 metres
  • Designed to enable an existing chimney to be utilised.
  • Available in 6, 8, 10, 11, 12, 14 and 16 metre flexi packs
  • Quick and simple to install
  • 100mm flue pipe diameter for boilers up to 46kW
  • 125mm flue diameter for boilers from 46-70kW
  • Smooth bore flexible stainless steel flue liner, specifically designed for condensing boilers
  • Single skin white powder coated extensions available in 150mm, 250mm, 450mm or 950mm fixed lengths and a 235-300mm adjustable length

Case Studies

Townsends take up renewables

Established in 1945, W.J Townsend & Son is a family run business providing domestic customers in Towcester and surrounding areas with a comprehensive range of plumbing and heating services. The business has been in the family for over 75 years with William John Townsend, founding the company. Andy his sonRead More

Grant Spira biomass boiler cuts fuel bills

A homeowner in Norfolk has noticed an immediate drop in fuel costs following the installation of a 26kW Grant Spira Wood Pellet Boiler by MCS Approved Green Home Energy Solutions. The Spira Wood Pellet biomass Boiler, which replaces an eighteen year old oil fired boiler, will provide heating and hotRead More

Grant biomass boilers are keeping installers busy

The social media feeds of Dryad Energy Ltd have been filled with red recently – red Grant Spira biomass (wood pellet) boilers! Dryad Energy has been incredibly busy installing Spira boilers in domestic properties throughout the South with photos from these installs occupying their newsfeeds. We have been speaking toRead More