I've got the same (see attached), and I'm thinking of trying the system without it when I fit my new pump. I'm not sure it does much, other than keep the pump primed. It does act like an accumulator to a certain extent.
Try a caravan shop, not a chandler, certainly not Bavaria.
BTW, I've changed your display name slightly, not a good idea to use an email address. Login remains the same, but I can change it if you like.