One way valves and hose sizes for vasic Jabsco 37010 electric system

[Chaff]

Hi everyone,

Thanks in advance for advice here. I have asked jabsco/xylem for technical support but no joy.

I have inherited 3 x Jabsco 37010 quiet electric heads each one discharging to a holding tank the tank entry is about 1.5 m vertically from the head discharge with about a 2 to 2.5 hose length in total.

After each heads joker valve is a approx 30 to 50cm length of 25mm hose (clearish..) into a 25/38mm whale one way (v. Similar to jabsco joker). On the other side rhe hose steps up to a 38mm for rest of journey to tank.

Head manual doesn't indicate extra valves required, nor step up to 38mm. It has been suggested the step up to 38mm can only 'hamper' the system as it creates so much extra pressure on the head to discharge into.

Anyone know what is 'correct' regards number and location of extra one way valves, recommendations on pipe size etc.

Thanks

Al