A water-side result does not establish combustion safety

A fictional heating replacement passes a documented water-side check. The contractor wants to hand over the appliance even though the combustion-air route, flue arrangement and protective-function records have not been confirmed. A worker points to a normal-looking flame as complete proof that carbon monoxide cannot be present. Another proposes using an old test pressure taken from a different country’s workbook. This written exercise operates no gas valve, burner or electrical circuit. Identify the independent circuits and safety questions that remain, explain the limits of visual flame appearance and describe the accountable current local and manufacturer basis needed before actual commissioning is accepted.