We are getting quite a few enquiries about the blue adjuster on the varistream circuit board, such as 'what is it for?' and 'what is the best setting?'.
The little blue adjuster on the circuit board is there to adjust the cut-off pressure of the pump. The exact setting of this blue adjuster depends on the pump you're using but more importantly it varies according to the window cleaning system you're pumping water through.
This means the 'best' setting varies for every customer.
We normally set the units to roughly 'F' as a factory setting, this results in pump model 8000-441-138 (our most popular waterfed pole pump) operating at pressures up to 100psi in a 'typical' window cleaning system. However if you have a different pump, or your system is not 'typical' (if there is such thing as a 'typical' system!) then a small amount of tweaking is occasionally necessary to calibrate the varistream to the pump.
To be honest, most people shouldnt have any need to adjust it, and the factory setting will suit most pumps and most waterfed pole systems.
In the simplest possible terms, if the pump runs completely smoothly and quietly (no cycling on and off) when you are cleaning windows, but when you disconnect the pole the pump switches off automatically in a few seconds and you don't observe 'ballooning' or other evidence of excessive pressure in your hoses, then you've got the blue adjuster in the right position.
If you turn it too far clockwise, then the pressure in your hoses when you disconnect the pole can become excessively high (150psi or even more) and there is a risk of over pressurisation, ballooning, hose connections popping off, and in extreme cases damage occuring.
If you turn it too far anticlockwise, then a situation can arise when the pump never gives enough pressure to deliver water to the end of the pole.
In the first few months of varistream manufacture we deliberately didnt draw attention to the blue adjuster, as we felt that a minority of customers could possibly cause problems by mis-adjustment and we felt it was best not to mention it. However as time went on we got quite a few enquiries asking what it was for, and also a small number of customers whose window cleaning systems were not 'typical' and the blue adjuster needed adjustment. Rather than talk each individual customer through the adjustment procedure we decided to add an instruction insert into the varistream pack when we despatch new units.
If you need further info, just give us a call and we can guide you through the adjustment process.
