Combo boiler vailiant - disc fitted to inlet do not use

If your Vaillant combi boiler has a disc fitted to the inlet with a warning not to use it, it likely means that the particular inlet or component should not be utilised. This could be due to compatibility issues, safety concerns, or specific installation requirements outlined in the manufacturer's guidelines. It's crucial to follow the provided instructions and consult with a professional if you have doubts or need clarification on the usage of specific components.