Many Installers understand the problem of siphoning associated with Mini Pumps. However here at Aspen we still speak to many who don't and we see the results of pumps which have been affected by siphoning returned to us, we also speak to many people whose first experience of the effects of siphoning are to hear the noise of the pump when it has to repeatedly prime itself.

Siphoning is a natural phenomenon which is easily understood once the effect of gravity and atmospheric pressure is full appreciated.

Most of us are familiar with the WC Siphonic Cistern coupled with our toilets many years ago we all had the old high up on the wall with a long chain pull type, (yes, I am that old) pull the chain release and water flushes down to the pan, a simple siphon, the trick is to get the effect into action, once the action is started the effect of atmospheric pressure on the stored water in the cistern and gravity on the already falling column of water in the pipe empties the cistern (see image to the bottom right: 'A Simple Siphoning Example'.)

The effect is exactly the same if a Mini Pump is connected to a long discharge pipe which falls below the level of stored water i.e. the sensor reservoir. Once the pump has begun the process of pumping the water and the column of water has past the point where gravity takes over the water will continue its journey to the end of the discharge tube even when the pump is switched off so draining all the remaining water. The next time the pump is signalled by the sensor to energise it has to pump air out to bring water to the internal pumping mechanism. We all know how noisy this can be for a few seconds until water completely fills the pump, this repeated many times in a few hours can be both very irritating to the customer and very wearing to the pump literally. The pump starts to wear out its internal parts, the result is it takes even longer to prime, more wear takes place the pump then gets even louder, very soon it fails completely.

It is possible to stop this effect in several simple ways and keep the pump from being noisy and failing prematurely.

(1) Install the pump so no siphoning can occur by routing the discharge line to a drain point level with the pump reservoir or even above the pump.
(2) Install the discharge line into a fixed drain line such as 20mm PVC overflow pipe to create an air break level with the pump reservoir, where the drain is at ground level (see left diagram as from our installation manual.)

(3) Install an Anti Siphoning Device.

The Anti Siphoning Device allows a small amount of air into the discharge line in a controlled way. This effect is only present when siphoning is actually occurring; at all other times it remains inactive. This device is therefore passively preventing this unwanted effect within the system sensing when the effect of siphoning is occuring.

The Anti Siphoning Device will be introduced with every Mini Pump from January 2012. Simply install the device in the discharge line near to the pump or in the ceiling above. This little device will take away the problem of siphoning and complaints about noisy pumps once and for all.