The water may not be up to the outlet level of the tank. Try raising the van on a slope or ramps so the tank outlet is tipped lower.Thanks for your very quick and helpful suggestions. The tap was definitely shut before and hose doesn’t seem to be kinked. It is a new van so will try the curtain wire! Thanks
Never fails to surprise me how long it takes to fill the water tank (except when we were allowed to use the high flow hose at a fish processing plant in Scotland although I ended up wearing a fair bit of it!!!). I always usually fill until it overflows the gagues are pantsThanks for your comment. It turns out the drain tank wasn’t actually full enough - rookie mistake! It ran off fine once we ran the taps through. We hadn’t calibrated the fill tank so thought it was full when actually it wasn’t. Lots to learn!! Appreciate everyone’s input.