A 22 mm Differential By-Pass Valve is a control component used in central heating systems to regulate water flow and pressure between the flow and return pipes. It helps maintain stable operation when parts of the system restrict flow, such as when thermostatic radiator valves or zone valves close.

Function & Purpose

The valve automatically opens when the pressure difference between the flow and return exceeds a set level, allowing water to bypass the main heating circuit. This prevents excessive pressure build-up, reduces noise, protects the circulation pump and boiler, and helps maintain consistent flow through the system. When pressure drops back to normal, the valve closes again.

Compatibility

This valve is designed for 22 mm pipework, making it suitable for most domestic and light commercial central heating systems that use this pipe size. It works with combi, system, and conventional boilers and is commonly installed near the boiler, pump, or manifold where pressure changes are most likely to occur.

Ideal Applications

A 22 mm differential by-pass valve is ideal for heating systems with multiple radiators fitted with TRVs, systems using zone valves, or installations where pressure-related noise or pump strain has been an issue. It is particularly useful in modern systems that frequently experience partial flow restriction and require stable, protected circulation.