What is required immediately ahead of each water supplied appliance?

The requirement for having a control valve immediately ahead of each water-supplied appliance is vital for ensuring safe and efficient operation. A control valve provides the means to regulate water flow to the appliance, which can be necessary for setting appropriate operational conditions and for maintenance or repair.

In plumbing systems, a control valve allows operators to manage water supply, especially for appliances that require specific flow rates or pressures to function properly. This feature is essential when servicing appliances, as it ensures that water can be shut off easily without affecting other fixtures or systems within the plumbing network.

While components like a shut-off valve also serve a similar purpose, the distinction lies in the specific functionality that a control valve provides, allowing for finer adjustment and control over the water supply rather than merely stopping flow. Other options, such as a flow meter or pressure gauge, serve different functions that do not directly pertain to managing the appliance's operation at a granular level.