Hello. We are in a 3 storey townhouse and have a megaflo, water softener and a system boiler. Pressure and flow on ground floor is fine but bathroom on middle floor has only 3 litres per minute. It is Dornbracht stuff, had engineer visit who said should be getting 5 out of tap and rainforest shower. Mains pressure is 2.8. Our plumber said we aren't getting pressure in our bathroom because there is a pre set valve on Megaflo which is set at 3 bar. As we have under 3 it effectively can't work to pressurise our water. Anyone know if this is correct/any way around it? Or have we completely wasted our money on the megaflo. Thanks.