What is the purpose of the non-return valve on a boiler?

The primary function of the non-return valve, also known as a check valve, in the context of a boiler is to prevent the backflow of steam into the boiler. This is crucial for maintaining safe and efficient operation of the boiler system. When steam is generated in the boiler and moves towards the steam header or distribution system, the non-return valve ensures that once this steam has exited the boiler, it cannot flow back into the boiler itself. Such backflow could potentially cause pressure issues or damage to the boiler components.

By keeping the steam moving in a unidirectional flow, the non-return valve also supports the overall stability and functionality of the heating system. This is especially important in applications where fluctuating pressures might occur and could lead to unintended consequences if steam were allowed to return to the boiler.