The Changing Cistern

The humble WC cylinder has quite undergone somewhat of a major facelift and re-design and is now quite a technological piece of kit. Take the capacity for example, since the 2gallons (9litres) that it held prior to 1993 was first of all dropped to 7½ litres and then onto the capacity held today of 6litres.

Flushing:
Your WC system probably uses something called a “Siphonic valve”, however the ultra modern cisterns fitted nowadays have a valve that will lift in order to carry out the flush. A Lee Plumber fits WCs. Older models relied on a float controlled valve to open and close the water supply inlet. On flushing, the float lowered when the water flowed out of the cistern, then this action would open up a fill valve fitted at the bottom of the cistern and re-fill again. When the float lifted to a pre-set point, and the water level was correct, it closed the inlet valve.

Siphonic:
When water leaves a cylinder with no kind of a mechanical help it is known as a siphonic action. The water moves up and over a tube looking like an upside down ‘J’. The long leg connects to the flush pipe with the short leg open to the water in the cistern. As soon as the air inside is removed, it creates a partial vacuum. This causes a large diaphragm washer to lift and allows a volume of water to discharge away through the flush pipework taking air and causing a partial vacuum. A Grove Park Plumber knows siphons.


Two Button:
The two flush button system is normally now fitted to a modern cistern, with one button designed to carry out a short flush (small volume of water) and a second button is designed to perform a long flush (large volume of water). These two use a double-rod system that controls the small and larger volumes of water that is needed by the user.
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