Home » Ariston Coaxial Extension 500mm Flue Extension Pipe
SKU: 3318078
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Ariston Coaxial Extension 500mm Flue Extension Pipe

Ariston
£23.00 Inc. VAT £19.17 Exc. VAT
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The Ariston Coaxial Flue Extension — 500mm (Part No. 3318078) is a genuine Ariston Ø60/100 mm extension pipe used to lengthen the flue run where the standard horizontal flue kit or vertical flue kit does not reach the wall or roof termination point. This 500mm extension is the shorter of the two Ariston extension options (the 1000mm alternative is Part No. 3318077), making it the preferred choice for fine-tuning the flue run length on installations where a full 1-metre extension would overshoot, or where space constraints make only a short additional run practical. Connection is push-fit throughout — no clamps or sealant are required.

500 mm
Extension Length
Ø60/100
Coaxial Diameter
Push-fit
No Clamps Required
⚠ Check Maximum Flue Run Before Adding Extensions: Each extension adds to the total effective flue length. Ensure the total run — including any elbows — does not exceed the maximum permissible flue length for your boiler model and flue diameter. Exceeding the limit causes inadequate combustion air supply and is a safety and regulatory breach. Always refer to the boiler installation manual.
Specification Detail
Part Number 3318078
Length 500 mm
Diameter Ø60/100 mm coaxial
Connection Push-fit with lip seal — no clamps or sealant required
Alternative Length 1000 mm — Part No. 3318077
Compatible Ranges E-Combi EVO, E-Combi ONE, Clas ONE, Genus ONE, Alteas ONE and Ariston HE boilers with Ø60/100 coaxial flue
Frequently Asked Questions
Can I cut the 500mm extension if my run is slightly shorter?
Ariston coaxial extension pipes can be trimmed — unlike the vertical flue terminal kit which must not be cut. Trim only the outer pipe, ensuring the inner flue pipe remains uncut. After cutting, deburr the outer pipe and confirm the lip seal still seats correctly before assembly.
How many extensions can I add to the horizontal flue kit?
You can add multiple extensions, subject to the maximum permissible flue length for your boiler. For the Alteas ONE+ NET 35 kW on Ø60/100, the maximum total run is 5 metres (including the terminal). For the E-Combi ONE boilers, the limits vary by output — always check the installation manual. One bracket per extension is required for adequate support.
Is there a silver 500mm extension to match the Alteas ONE NET?
Yes — Part No. 3319165 is the 500mm extension in the silver colourway, matching the Alteas ONE NET's aesthetic. It is mechanically identical to 3318078.
Should the flue run slope toward the boiler or toward the terminal?
Horizontal flue runs should slope slightly downward toward the terminal (a fall of approximately 2–3° or 44 mm per metre) to allow condensate formed in the flue to drain away from the boiler. This also prevents low points where condensate could pool and cause corrosion or flue blockage. Ensure no low points exist in the flue run when laying out extensions and bends.
BTU & WATT Calculator
Room Dimensions
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