S9 Hi-Flo Syphon

A WRAS approved one-piece syphon. 6/7/9 litre convertible.


The S9 Hi-Flo provides a reliable toilet syphon replacement for most high level and low level application


  • 6/7/9 Litre One Piece Syphon, suitable for high and low level use.
  • 38mm [1/5"] Outlet
  • Other sizes available please enquire
  • Compatible in most low-level lever operated cisterns.
  • 5 working day dispatch


A syphon can be used as an internal overflow device, as long as the spillover point of the syphon is below any other external hole within the cistern body, normally the lever hole.

To find the correct height of the required syphon for a cistern, measure the depth of the water level line, within the cistern, normally marked at the back of the cistern, and then add 1” or 25mm to this measurement. This will give you the height of the required syphon. (Cisterns fitted before 2001, would have an original syphon in them that would be approx. 1 ½” or 40mm taller than the current requirements).

When fitting a syphon to a close coupled toilet, you need to ensure that the threaded tail of the syphon is trimmed back, to ensure that the syphon flush is not throttled back, giving you a poor flush. We recommend that the tail is trimmed back to 2-3mm from the back nut.

A syphon is measured from the bottom flange of the threaded tail, to the spillover point of the syphon, this is the effective height of the syphon. When choosing a Syphon the Height Stated will be the height to the spill over point and Not the Overall Height of the Syphon. (i.e. an 8” syphon would be 8” to the spill over, whereas the overall height would be 10” )

The operation of the dual flush syphon, is to flush and release the lever to give you a full flush, and to flush and hold the lever down, to give you a reduced flush. By holding the lever down, this lifts up two washers (one small blue plastic and one small black rubber) that are located immediately below the metal C link. When these washers are lifted up, this allows air to enter the syphon and breaks the syphonic action, the water level in the cistern will drop to just below the top of the syphon body, therefore giving you a reduced flush.

A syphon will internally overflow when the water level within the cistern reaches the spillover point. The water will trickle over the spill over point, and run down the downleg of the syphon, and into the toilet bowl.

These are to reduce the flush volume of the syphon within the cistern. By removing the plugs you will reduce the volume of water supplied on the full flush. If no plugs are removed, the water in the cistern will drop to the bottom of the syphon body. If the bottom plug is removed, the water in the cistern will only drop to this level. If the top plug is removed, the water in the cistern will only drop to this level.

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