Pressure Reducing Valves (PRV)
Maintain optimal water pressure in your plumbing system with our range of WRAS approved pressure reducing valves
What is a Pressure Reducing Valve?
A pressure reducing valve (PRV) automatically reduces high water pressure from the mains supply to a safe, usable level for your plumbing system. By maintaining consistent lower pressure, PRVs protect pipes, fixtures, and appliances from damage while improving efficiency and extending component lifespan.
Protects System
Prevents damage to pipes, joints, and appliances caused by excessive pressure
Improves Efficiency
Reduces water consumption and energy waste in heating systems
Extends Lifespan
Lower pressure stress reduces wear on valves, pumps, and connections
WRAS Approved
Safe for potable water with full regulatory compliance
Types of Pressure Reducing Valves
Direct Acting PRVs
How they work: A spring-loaded piston responds directly to downstream pressure. As pressure increases, the piston rises and closes the valve.
Characteristics:
- Simple, reliable design with fewer components
- Compact and cost-effective
- Suitable for small systems with stable flow
- Low pressure drop across the valve
- Sensitive to small flow rate changes
Best for:
Domestic plumbing, property isolation points, and small-scale applications where consistent pressure control is needed.
Pilot Operated PRVs
How they work: A small pilot valve controls the flow to a main valve. The pilot responds to pressure changes and modulates the main valve opening.
Characteristics:
- Precise pressure control with minimal variation
- Handles higher flow rates efficiently
- Better performance across variable demand
- Suitable for large buildings and complex systems
- More components means slightly higher cost
Best for:
Commercial buildings, multi-story properties, and systems with variable flow demands where precise pressure regulation is essential.
Pressure Relief Valves
How they work: Opens to release pressure when it exceeds a set limit, then closes as pressure drops back to safe levels.
Characteristics:
- Provides emergency over-pressure protection
- Spring-loaded design for rapid response
- Typically mounted at system high points
- Works alongside PRVs in comprehensive systems
- Essential for safety in pressurized systems
Best for:
Boiler systems, sealed heating systems, hot water cylinders, and any pressurized application requiring safety protection.
Materials & Construction
Brass
Most common choice for domestic applications
- Excellent corrosion resistance
- Compatible with all pipe materials
- Easy to install with standard fittings
- Cost-effective and reliable
- WRAS approved for potable water
Stainless Steel
Premium option for superior durability
- Superior corrosion resistance
- Non-reactive with water
- Longer service life in challenging environments
- Higher initial cost offset by longevity
- Ideal for commercial installations
Bronze
Traditional option for larger valves
- Excellent corrosion resistance
- Used for larger diameter valves
- Durable in aggressive water conditions
- Traditional specification
- Higher strength and reliability
Material Selection Tips
- For domestic plumbing: Brass is the standard choice, offering excellent value and performance
- For hard water areas: Consider stainless steel for maximum corrosion resistance
- For commercial/large systems: Bronze construction provides strength and durability
- All materials: Must comply with WRAS requirements for potable water contact
Pressure Reducing Valve Applications
Domestic Water Supply
Most UK homes experience mains pressure between 4-8 bar. A domestic PRV reduces this to 2.5-3.5 bar, the optimal level for household plumbing. This protects pipes, valves, and appliances while reducing noise and water consumption.
Typical installation: Inside the property after the main stop tap
Commercial Buildings
Multi-story buildings require sophisticated pressure regulation systems. Different floors experience different pressures due to height variation. Pressure reducing valves installed at key distribution points ensure safe, consistent pressure throughout the building.
Typical installation: At zone entry points and floor distribution risers
Boiler Protection
Modern boilers are sensitive to mains pressure variations. A dedicated PRV at the boiler inlet prevents surges and maintains stable operating conditions, improving efficiency and reliability.
Typical installation: On the cold water inlet to the boiler supply
Mains Pressure Reduction
When incoming mains pressure is excessively high (above 6 bar), a main PRV installed at the property entry point protects the entire system. This is essential in areas served by high-pressure mains supplies.
Typical installation: Immediately after the main stop tap
Hot Water Cylinder Protection
Sealed hot water systems expand as they heat. A PRV on the inlet prevents pressure build-up that could rupture the cylinder or force water back into the mains supply.
Typical installation: On the cold supply inlet to the cylinder
Appliance Protection
Washing machines, dishwashers, and other appliances have inlet pressure limitations. Installing a PRV protects these expensive devices from pressure-related damage and extends their service life.
Typical installation: On dedicated appliance supply lines
Size Range & Selection
Pressure reducing valves are available in sizes from 15mm up to 100mm to suit residential, commercial, and industrial applications.
| Valve Size | Connection Type | Typical Application | Flow Rate (approx) |
|---|---|---|---|
| 15mm | Compression/Push-fit | Single property, zone control | 15-20 l/min |
| 22mm | Compression/Push-fit | Small-medium property | 30-50 l/min |
| 28mm | Compression/Flanged | Medium-large property | 60-100 l/min |
| 35mm | Flanged | Large property, multi-zone | 120-180 l/min |
| 50mm+ | Flanged/Threaded | Commercial buildings | 250+ l/min |
Selecting the Right Size
- Match the valve size to your main incoming water pipe diameter
- Consider future demand and expansion potential
- Over-sizing causes poor pressure regulation; under-sizing restricts flow
- For multi-zone systems, select larger valves for main distribution points
- Consult the original system design for guidance
Standards & Compliance
BS EN 1567
The primary British and European standard for pressure reducing valves. Covers design, manufacture, testing, and performance requirements for PRVs used in plumbing systems.
WRAS Approval
Water Regulations Advisory Scheme approval guarantees compliance with UK water regulations. All our pressure reducing valves suitable for potable water are WRAS approved, ensuring safe contact with drinking water and regulatory compliance.
Building Regulations Compliance
Installation of pressure reducing valves helps meet Building Regulations requirements for system pressure control and protection. Proper specification and installation ensure your project meets all regulatory requirements.
Compliance Checklist
- ✓ Choose WRAS approved valves for potable water applications
- ✓ Verify BS EN 1567 compliance
- ✓ Ensure correct size and pressure rating for your system
- ✓ Install at appropriate distribution points
- ✓ Include isolation valves for maintenance access
- ✓ Consider relief valves for sealed systems
- ✓ Document installation for building control approval
Installation Guidance
Step 1: Site Survey
Measure incoming mains pressure with a gauge. High pressure (above 6 bar) indicates the need for a main PRV. Check flow requirements and identify optimal installation location.
Step 2: Select Valve Type & Size
Choose between direct acting (small systems) and pilot operated (large systems) PRVs. Select size to match incoming pipe diameter. For domestic installations, 15mm or 22mm valves are typical.
Step 3: Choose Installation Location
Install the main PRV immediately after the main stop tap and before any branch connections. Include isolation valves on both sides of the PRV for future maintenance. In some systems, zone PRVs may be installed at distribution points.
Step 4: Install Isolation & Strainer
Install a strainer upstream to protect the valve from debris. Include isolation ball valves on inlet and outlet for service access. Ensure adequate space for pressure gauge connection.
Step 5: Connect Pressure Gauge
Attach a pressure gauge to the outlet side of the valve to monitor reduced pressure. This aids commissioning and future system diagnostics.
Step 6: Adjust & Commission
Set the PRV to deliver 2.5-3 bar outlet pressure for domestic systems. Allow 15-30 minutes for the system to stabilize before final pressure checks. Higher commercial settings require engineering calculations.
Important Installation Notes
- Always allow time for pressure stabilization after adjustment
- Check outlet pressure under various flow conditions
- Include expansion vessel on sealed systems to absorb pressure spikes
- Install a relief valve if backflow prevention is needed
- Ensure adequate drainage provision if the valve vents
- Document the installed pressure setting for maintenance records
Understanding Pressure Reducing Valves: A Complete Guide
Water pressure in UK plumbing systems can vary significantly. Mains pressure typically ranges from 3 to 8 bar, depending on your location and water utility provider. While this high pressure is delivered to your property for practical reasons—to reach upper floors and ensure adequate flow—it can be damaging to household plumbing systems designed to operate safely at much lower pressures.
Why You Need a Pressure Reducing Valve
Excessive water pressure stresses pipes, joints, valves, and appliances. Problems associated with high pressure include:
- Noisy pipes and fixtures (water hammer)
- Premature failure of ball valves and washers
- Leaks at compression fittings
- Reduced lifespan of appliances like washing machines and dishwashers
- Higher water consumption
- Increased heating costs in hot water systems
How Pressure Reducing Valves Work
A pressure reducing valve automatically reduces high incoming water pressure to a safe, consistent level. The valve uses a spring-loaded mechanism that responds to downstream pressure. When pressure exceeds the set level, the valve gradually closes to restrict flow. When pressure drops below the set level, the valve opens to allow more flow. This self-regulating action maintains consistent output pressure regardless of variations in inlet pressure or water demand.
Pressure Reducing Valve Benefits
Installing a correctly sized and configured pressure reducing valve provides multiple benefits:
- System Protection: Reduces stress on pipes and components, extending their lifespan
- Cost Savings: Lower pressure means less water waste and reduced heating energy
- Quieter Operation: Eliminates water hammer and noise from high-pressure surges
- Improved Performance: Optimal pressure improves flow to showers, baths, and appliances
- Regulatory Compliance: Required in many installations under Building Regulations
Types of Pressure Reducing Valves Explained
Different PRV types suit different applications. Direct acting valves are simple and effective for small residential systems with stable demand. These valves contain a spring-loaded piston that responds directly to downstream pressure, offering cost-effective and reliable operation. Pilot operated valves provide superior performance for larger systems with variable demand, using a small pilot valve to control the main valve, enabling precise pressure regulation across different flow rates. Pressure relief valves provide emergency over-pressure protection, typically used alongside PRVs in sealed heating systems.
Selecting the Right Material
Pressure reducing valve bodies are commonly manufactured from brass, stainless steel, or bronze. Brass is the standard choice for domestic applications due to its excellent corrosion resistance, compatibility with standard fittings, and competitive cost. Stainless steel offers superior performance in challenging water conditions or for premium installations. Bronze is used for larger diameter valves where maximum durability is required. All materials must be WRAS approved for potable water applications.
Professional Installation Considerations
While pressure reducing valves are straightforward in principle, proper installation is critical for optimal performance. The valve should be installed immediately after the main water stop tap, allowing it to protect the entire internal system. Isolation valves on both sides enable future maintenance without draining the whole system. Including a strainer upstream protects the valve from debris. A pressure gauge outlet allows system monitoring and commissioning. For sealed heating systems, a relief valve should be installed to protect against over-pressure conditions.
Proper pressure setting is equally important. Domestic systems should operate at 2.5-3 bar for optimal performance. Commercial installations may require different settings based on building height and system design. Regular monitoring ensures the valve continues operating at the correct setting.
Need Help Choosing the Right Pressure Reducing Valve?
Our expert team can advise on valve selection, sizing, and installation for your specific project.