Safety & Relief Valves

Safety & Relief Valves for Heating & Hot Water Systems

Safety and relief valves are critical components in heating and hot water systems, designed to protect cylinders, pipework and appliances from excess pressure and temperature. Whether you're replacing a pressure relief valve (PRV), temperature and pressure relief valve (T&P valve), or expansion relief valve, selecting the correct specification is essential for safe system operation.

At Heatraq, we supply a range of safety and relief valves suitable for domestic and commercial applications, including genuine Heatrae Sadia and Baxi parts. Use the filters or product listings below to find the correct replacement based on pressure rating, connection size and system type.

What Do Safety & Relief Valves Do?

Safety and relief valves are designed to prevent dangerous pressure or temperature build-up within a heating or hot water system. When system conditions exceed safe limits, the valve automatically opens to release water, helping to protect the cylinder, pipework and connected components from damage.

These valves are commonly installed on unvented hot water cylinders, stored hot water systems and heating circuits, where pressure control is essential for safe operation.

Types of Safety & Relief Valves

Pressure Relief Valves (PRVs)

Designed to release water when system pressure exceeds a set level, helping to prevent damage to cylinders and pipework.

Temperature & Pressure Relief Valves (T&P Valves)

Provide dual protection by responding to both excess pressure and high water temperature, commonly used on unvented cylinders.

Expansion Relief Valves

Used within expansion control systems to manage pressure increases caused by water expansion during heating.

Choosing the Correct Safety Valve

When selecting a replacement safety or relief valve, it is important to match:

  • Pressure rating (e.g. 3 bar, 6 bar, 7 bar)
  • Temperature rating (where applicable)
  • Connection size and type
  • Manufacturer and model compatibility
  • Valve type and application within the system

For safety-critical components, always match the original manufacturer's specification wherever possible.

Installation & Safety Considerations

Safety and relief valves are essential protection devices and must be installed correctly to function as intended. Incorrect installation or specification can lead to system failure or safety risks.

For unvented cylinders and pressurised systems, installation and replacement should be carried out by a qualified professional in line with UK regulations.

Related Valve Categories

Safety and relief valves are often used alongside other valve types within a complete heating or hot water system.

Depending on the system design, they are commonly installed alongside water control and regulation valves to manage incoming pressure, and isolation and service valves to allow safe maintenance, servicing and replacement of components.

Frequently Asked Questions

What is a safety or relief valve?

A safety or relief valve is a protective component that automatically releases pressure or temperature from a heating or hot water system when it exceeds safe limits.

What is the difference between a PRV and a T&P valve?

A pressure relief valve (PRV) responds only to pressure, while a temperature and pressure (T&P) valve responds to both high pressure and excessive temperature.

Where are safety valves installed?

They are typically installed on unvented hot water cylinders, expansion vessels and heating systems where pressure control is
required.

How do I know what pressure rating I need?

The correct pressure rating should match the original valve or system specification. Using the wrong rating can affect system safety and performance.

Can a faulty relief valve cause leaks?

Yes, if a valve is faulty or worn, it may discharge water continuously or intermittently, which often appears as a leak.