www.williamsonpumps.co.uk Check this site for all the info on the varistream. It does away with the need of a pressure switch on your pump, in fact it takes over from it, so you have to make sure you disconnect the pressure switch on the pump before fitting the Varistream.
It sends an electric pulse out every few seconds to check and compensate for any height you are working at. It senses any stop in flow and stops the pump accordingly. This dramatically prolongs both pump and battery life.
There is a little dial inside the Varistream box that allows you to set what pressure you want it to turn off the pump.
If you are using micro bore hose, you may find that you can't use the varistream on maximum flow. In practice it makes no difference as I never need the maximum, it would be throwing water jets 30 ft long, and that's with my 60psi Sureflow pump.
If you think about what's happening when you pump water at high pressure. It gushes down your hose, until it comes up against the restriction of connectors and jets. This causes a build up of pressure, that backs up until it reaches the pressure switch. The pump is then turned off, almost immediately it turns back on again as the pressure drops. This constant on off cycle will eventually burn out the pressure switch. The Varistream stops the pump electronically and prevents this happening.
The pump does start when the electronic pulse hits it, you will here this even if the flow is turned off, this is perfectly normal as the chip inside the Varistream depends on the feedback it gets from the pump.Dai
