They can be a real pain to set up at times.
When you think about it the, only thing the Varistream can do is regulate the pump speed and the pressure cut of point, but it does have that number and letter combination that's a mystery to me too.
In normal use you have a figure say number 4 on the display, when you push the setting button and hold it in a letter comes up, push the button again and the letter starts flashing, push again and the next letter comes up.
If you carry on doing this you go through all the letters and then numbers come up again, but these are not the same numbers that are on display during normal use. my guess is that these second numbers are to allow 10 pressure cut off points for each letter. In practise it doesn't work out this way as say a setting of 4 B 9 gives a higher cut off point than 4 C 2.
The settings on mine may read exactly the same for days at a time, but sometimes the thing has a mind of it's own and creates far too much pressure.
I lost the instructions for mine, does anyone know exactly how these thing work?
I would love to run my system with the same flow and pressure cut off as the Surflow backpack running flat out.