As per normal, I'm not sure I understand the question correctly. However, I'd mention that without the EV, the flow from the majority of pumps is variable, which may well cause problems with a washing machine. I have the mechanical type pressure switch, and my plumber keeps recommending the electronic type as being a more constant flow.
Contadino - can you explain what you mean by EV ?
I ended up buying a diverton 1000 pump (not sure whether the pressure switch in it is mechanical or electronic) but the bloke did mention about possible damage to washing machines ---- I would like to know more about the risk to my washing machine..........
EV - Expansion vessel. When you're pumping, you need something to smooth the flow of water, and to stop it pulsing (I reckon that there's an English word for it, but that's just what the Italian translates to.) When the tap is open, and the pump starts, the pressure shoots right up and then drops right down again - the more powerful the pump, the worse it is. It also reduces the number of times the pump kicks in when there's a high water demand, reducing pump wear.
Most washing machines and dishwashers kind of rely on having a fairly stable flow rate and a certain pressure. That's why you can have issues with the machines if using gravity feed. My pressure switch clicks on at 1 bar and off at 2, and whilst I'm sure it's not good for the washing machine, I wouldn't want the pressure to drop below a bar.
A few surface pumps have a built in EV, but I've just done a quick google of yours and it looks like a submersible one, so my advice would be to stick a little (10 ltr?) EV somewhere between the pump and the point of use.
