FLUE GUIDE

Maximum Permissible Flue Lengths

Horizontal Concentric Flue Length

Maximum permissible horizontal concentric flue length combining both horizontal flue and flue extensions (measured from centreline of the turret to the outside of the wall terminal):

• Up to 26 kW appliances: Maximum 9m - minus any extensions or bends
• 30 & 32 kW appliances: Maximum 8m - minus any extensions or bends
• 35 & 38 kW appliances: Maximum 6m - minus any extensions or bends

Vertical Flue Length

Maximum permissible vertical flue length combining both vertical flue terminal and flue extensions:

• 24 - 38 kW appliances: Maximum 7.5m - minus any extensions or bends
• Vertical flue loft air inlet (24 - 38 kW): Up to 4.7m concentric flue and 20m single flue pipe. For additional configurations and details refer to the installation instructions.

Equivalent Flue Length Resistance

• 90° bend Ø60/100: Equivalent flue length resistance = 1m
• 45° bend Ø60/100: Equivalent flue length resistance = 0.6m

Flue Accessories

A comprehensive range of flue accessories is available for Ideal Logic² boilers.

Flue Options & Configurations

Horizontal Concentric Flue with 1 x 90° Bend

Components: Horizontal flue non-telescopic 0.6m (Part No. 208171), Flue extension 1m with bracket (Part No. 203129).

Horizontal Flue with 2 x 90° Bend

Components: Horizontal flue non-telescopic 0.6m (Part No. 208171), Flue extension 1m with bracket (Part No. 203129), Flue bend 90° (Part No. 203130).

Horizontal Flue with 2 x 45° Bend

Components: Horizontal flue non-telescopic 0.6m (Part No. 208171), Flue extension 1m with bracket (Part No. 203129), Flue bend 45° pair (Part No. 203131).

Vertical Flue System Configurations

Vertical Flue System with 2 x 45° Bend

Components: Vertical flue terminal and connector (Part No. 211039), Flue extension 1m with bracket (Part No. 203129), Flat roof weather collar (Part No. 152259).

Vertical Flue with Loft Air Inlet

Description: This configuration allows the boiler to be sited where no outside wall access is available. The concentric flue runs vertically from the boiler, obtaining air supply within the roof space, with the secondary flue continuing to the external flue terminal. Offset applications are permissible, though the maximum length is reduced.

Components: Air inlet for vertical flue (Part No. 203136), Flue vertical connector (Part No. 208175), Vertical flue terminal (Part No. 203134), Weather collar pitched roof (Part No. 152258), Flue extension 1m with bracket (Part No. 203129), Flue extension 1m pair (Ø80mm) (Part No. 203142).

High Level Flue Outlet Kit

Description: These kits allow the boiler flue outlet to be extended externally, upwards, to provide a flue exit at high level, overcoming problems associated with plume emission. The kit is simple to retrofit. An external 60mm diameter flue leads from the boiler terminal (which includes a 90° bend at the flue exit) to terminate with a 90° bend complete with grille. Push-fit 1m extension pipes are used as required, and fixing clips support the system from the wall. Both 90° and 45° bends are available for routing options.

Important Note: Flue must always slope at least 1.5° back to the boiler.

The kit typically comprises: Flue bend (1 off), 60mm flue exit bend (1 off), 60mm horizontal flue exit (1 off), 60mm x 500mm flue extension pipe (1 off).

Compatibility: This kit is for use with horizontal non-telescopic and telescopic flue kits (Part Nos. 208169, 208171, 208174, 217442). The standard terminal nose is replaced with the high-level terminal.

Components for High Level Flue Outlet:

• Horizontal flue non-telescopic 0.6m (Part No. 208171)
• High level flue outlet kit (Ø60mm) (Part No. 208178)
• Flue extension 1m for high level flue outlet (Ø60mm) (Part No. 203228)
• High level flue bend 90° (Ø60mm) (Part No. 229130)
• High level flue bend 45° (Ø60mm) (Part No. 229131)

Note: Refer to the installation and service manual for assistance in calculating flue lengths. Adequate support must be provided for the flue in accordance with the installation instructions. If additional elbows are used, deduct their equivalent flue length resistance from the maximum boiler flue length.

Flue Accessories for High Rise Installations

Regulatory Context: Building Regulations (Amendment) 2018 (England) mandate that combustible materials must not be used in the external walls of high-rise residential buildings (above 18m tall). This affects gas boilers with horizontal flues containing combustible materials like polypropylene inner flue ducts. Similar regulations apply in Wales and Northern Ireland, with Scotland having its own rules.

Product Features: Ideal Heating offers high-rise flue accessories that comply with these revised regulations. Introduced from October 2019, they are direct replacements for standard horizontal flues and accessories. The primary difference is the use of an aluminium inner flue duct, which has class A fire resistance according to European Standard prEN1856-1.

Appearance: Externally, high-rise flues resemble previous Ideal Logic flues (pre-2013). The terminal is black plastic, and the outer air duct has a galvanised finish instead of powder-coated white. The terminal, elbow, and wall seals are not affected by the regulations as they are not part of the external wall makeup. The terminal design features an air inlet underneath, through which the aluminium flue duct is visible.

Compatibility Limitations: High-rise horizontal flue terminals do not have a removable terminal nose. Consequently, they cannot be used with the following standard accessories: 208178 (High level flue outlet kit), 211302 (Soffit kit), 208177 (Balcony flue outlet kit), and 208176 (Flue deflector).

Dedicated High-Rise Accessories: New accessories are available to cover more installation configurations, all featuring aluminium flue ducts to comply with amended regulations.

Flue Siting Guidelines

A substantial number of flue options are available, providing excellent siting flexibility for almost all applications, including standard, telescopic, vertical, and raised horizontal options. High Level Flue Outlet kits and Flue Deflectors are also available to help minimise siting issues.

Flue Terminal Position Minimum Spacing Requirements

The following table details minimum spacing requirements for flue terminals:

*Note: Only one reduction down to 25mm is allowed per installation.

Diagrammatic Siting Examples

The following describes common siting scenarios illustrated in the original document:

• Diagram 1 (General Spacing): Illustrates various minimum distances from boundaries, openings, and other features, including 300mm, 600mm, 1200mm, 1500mm, 2000mm, and 300mm measurements depending on the specific configuration (e.g., from openings, boundaries, adjacent windows).
• Diagram 2 (Boundary Alignment): Shows configurations for "Facing the boundary" and "Parallel to the boundary," detailing required clearances such as 600mm, 300mm, and 2000mm.
• Diagram 3 (Angled to Boundary): Depicts a scenario where the flue is installed at an angle to a boundary, with specific measurements indicated.
• Diagram 4 (Below Ground Level): Defines two key measurements: Height Difference 'A' and Fixed Separation Distance 'B'.
  • If Height Difference 'A' is less than 300mm, then Separation Distance 'B' must be 300mm.
  • If Height Difference 'A' is greater than 300mm, then Separation Distance 'B' must be 1500mm.
  • A fixed separation distance 'B' of 690mm or 625mm is also shown in relation to other measurements.

Contact Information

For customer service or technical assistance:

• Customer Service: 01482 498660
• Technical Help: 01482 498663

Address: Ideal Heating, PO Box 103, National Avenue, Kingston upon Hull, East Yorkshire, HU5 4JN

Email: enquiries@idealheating.com

Website: idealheating.com/installers