22mm bypass valves are designed to regulate and maintain consistent water flow in central heating systems, even when thermostatic radiator valves (TRVs) or zone valves are closed. By automatically redirecting water around the system, these valves help prevent excess pressure, protect the boiler, and reduce noise caused by water hammer or pump strain.Essential in modern heating installations, a bypass valve ensures that water continues circulating when parts of the system shut down — preserving boiler efficiency and extending component life. The 22mm size makes them suitable for mid-sized residential systems, and many models come with adjustable pressure settings to fine-tune flow based on system needs. Whether retrofitting or installing new, a 22mm bypass valve provides essential system stability.

Key features and benefits of these valves.

Key Features

Redirects water when TRVs or valves close, protecting the boiler from excess pressure. Prevents short cycling and unnecessary wear on your heating pump.

Key Features

Allows fine-tuning of pressure thresholds for optimal performance. Supports a wide range of system configurations and flow requirements.

Key Features

Reduces water hammer and system noise by allowing smooth bypass flow. Improves overall comfort and performance in sealed heating systems.

As more heating systems move toward efficiency with thermostatic radiator valves (TRVs) and zone control, managing excess system pressure becomes essential. A 22mm bypass valve automatically opens when flow is restricted elsewhere, protecting the boiler and pump from damage or stress. This not only improves performance but helps maintain a quiet, efficient, and long-lasting heating system.

Without a bypass valve, closed TRVs can cause pressure to rise, leading to short cycling, noise, or costly breakdowns. A simple 22mm bypass valve provides peace of mind by keeping your system balanced — even when everything else shuts down.

You’ll typically find 22mm bypass valves installed on the flow or return pipe near the boiler or central heating pump. They’re often placed between the flow and return to allow excess pressure to bypass radiators and re-enter the system loop. In homes with multiple TRVs or motorised zone valves, bypass valves are especially important for maintaining circulation.

These valves are also common in sealed heating systems where pressure must be automatically controlled without a manual intervention. Their 22mm sizing makes them ideal for most standard UK pipework in residential and light commercial settings.

It’s used to maintain flow and prevent pressure build-up in a heating system when certain zones or radiator valves close. It ensures water can still circulate properly even if other parts of the system shut off.

It helps protect pumps and boilers from excessive pressure when TRVs (thermostatic radiator valves) or zone valves close by providing an alternate route for water to flow.

In many modern sealed systems, especially with multiple TRVs or motorised zone valves, a bypass valve is highly recommended — and sometimes required by building regulations.

It opens automatically when system pressure exceeds a set threshold, allowing water to flow through the bypass line to relieve pressure.

Yes — many models have an adjustable pressure setting so you can fine-tune when the valve opens based on system requirements.

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Usually between the flow and return pipes, near the boiler or pump, to provide an alternate route for water when other paths are closed.

No — when correctly set, it only opens when necessary, preventing energy waste and supporting consistent flow and boiler operation.

Yes — especially in systems with multiple TRVs. It ensures proper circulation when all radiator valves are closed.

It’s ideal for medium-sized domestic heating systems using 22mm pipework, often the standard for central heating loops.

No — a bypass valve reroutes water internally within the system, while a pressure relief valve discharges water externally to relieve pressure.

Yes — by preventing pressure build-up, it can reduce noise caused by cavitation, water hammer, or pump strain.

They’re low maintenance but should be checked during annual servicing to ensure they're functioning and correctly set.

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