Why is a control valve required ahead of water-supplied appliances?

A control valve is essential ahead of water-supplied appliances because it allows for the quick and efficient stopping of water flow, which is particularly important during maintenance activities. When servicing an appliance, being able to isolate it from the water supply helps prevent potential flooding, water damage, or other hazards that could occur if maintenance work is conducted while water is still flowing. This aspect of safety and control is a key reason for having such a valve in place.

While other reasons like preventing leaks or regulating temperature play roles in plumbing systems, the primary focus of a control valve in this context is its ability to facilitate safe maintenance procedures. Proper drainage, while important, is not the primary purpose of a control valve being positioned ahead of appliances.