Can anyone tell me if there is any situation where, on an open vented system, you wouldn't have an expansion pipe on either the cold water cistern or the F&E tank? I came across it today. Looked like a decent install otherwise but it struck me as odd. The owner said he'd been told by the installers that it didn't need one. I only went there to put a radiator back on that I'd taken off the week before so they could decorate. I offered to check the ball cock was working properly after refilling the radiator but noticed there were no F&E pipes. Anyone any ideas why?