Get in touch.

Say hello

T: 01298 812371
F: 01298 812237

Find us

HD Sharman Ltd.
High Peak Works,
High Peak,
Derbyshire SK23 0HW

The challenge to refurbish gutters with syphonic drainage outlets

Originally developed in Scandinavia in the 1960s, syphonic drainage became increasingly specified in the UK from the late 80s on large commercial and industrial buildings. As a principle, syphonic drainage is a simple one. Traditional drainage systems use gravity to pull a combination of rainwater and its surrounding air from the gutter into the drainage outlet. Typically, one litre of water is mixed with 35 litres of air into a 100mm downpipe and the rainwater system is designed accordingly. By contrast, syphonic drainage systems are designed to prevent air entering into the outlet and use the resulting suction forces to syphon water (not air) at high velocity from the gutter. Baffle plates inserted into each outlet restrict air intake and it’s the combination of the accumulated weight of water in the system and lack of air that creates a vacuum that then syphons the rainwater into the pipework at high speed. The key design benefits are:

  • A reduced number of outlets and downpipes
  • Horizontal design options
  • Faster flow rates (up to 8 times faster)


Historically, the only approach to failing gutter systems with leaking syphonic outlets was to replace the system in full which proved both expensive and disruptive to the building performance/occupants and could require taking the roof off. This proved particularly problematic in systems that were failing within 10-15 years of their installation. In response to this increasing demand from both building managers and specifiers to refurbish existing syphonic gutter systems, Sharmans developed its BBA accredited and 25 year guaranteed Plygene Gutterline system. Designed specifically for the harsh rigours of the gutter environment as a “gutter within a gutter,” its bespoke made-to-measure components include engineered syphonic kits as an integral design element of the system. This ensures that the existing gutter and syphonic outlets can be (re) lined without compromising the integrity or efficiency of the system’s performance design.



As Clive Draper, Sharman’s Technical Services Manager, explains “We have developed bespoke moulded kits to match the different profiles and operational features of the most common types of syphonic outlets including ranges from Sapaflow, Fullflow, Acquaphonx, AeroMekano, Geberit Pluvial and Dallmer and we are constantly adding to the list to meet growing demand. By extending the life performance of gutter systems with syphonic outlets, we provide speedy, cost effective and quality assured solutions for building managers and specifiers with minimal building disruption”.

For more information, contact or call our technical helpline 01298 875 007.

Clive Draper