What is a PRV Valve? A Guide to Pressure Reducing Valves

A pressure reducing valve plays a crucial role in protecting and enhancing the performance of plumbing systems. Its key functions include:

• Reducing Excessive Water Pressure: Safeguards plumbing from damage caused by high pressure.
• Ensuring Consistent Pressure: Maintains a stable flow, ensuring reliable system performance across various appliances.
• Protecting Appliances: Shields sensitive appliances like water heaters, washing machines, and dishwashers from pressure surges that could cause harm.
• Improving Water Flow Control: Enhances system efficiency by regulating water flow and ensuring optimal performance.
• Conserving Water: Reduces unnecessary water usage, promoting sustainability and lowering utility bills.
• Extending the Lifespan of Plumbing: Minimises wear and tear on pipes, fixtures, and connected devices, contributing to long-term durability.
• Stabilising Pressure Fluctuations: Prevents erratic pressure changes, improving the overall reliability of the system.
• Preventing Water Hammer: Mitigates the occurrence of noisy, banging pipes, ensuring a quieter, more comfortable living environment.

By managing pressure effectively, a PRV helps maintain the efficiency and longevity of plumbing systems while also preventing potential damage and costly repairs.

Pressure reducing valves (PRVs) are designed to lower and regulate high water pressure from the inlet to a consistent and manageable level at the outlet, ensuring efficient water flow and protecting plumbing systems. Here’s how they function:

High-Pressure Water Enters the Valve: Water from the mains supply flows into the PRV, which is designed to handle varying inlet pressures that can range widely (e.g., 1 bar to over 20 bar).

Spring-Loaded Piston and Diaphragm Mechanism: The valve uses a spring-loaded piston and diaphragm to regulate pressure. The user sets the desired outlet pressure using an adjustment dial or wheel on the valve. This adjusts the tension on the compression spring, which holds the diaphragm in position.

Dynamic Pressure Control: If the upstream pressure remains at or below the desired downstream pressure, the spring keeps the valve open, allowing water to flow through. When demand on the downstream side causes a pressure drop (known as fall-off pressure), the valve remains open to maintain flow.

Static Pressure Control: If the upstream pressure exceeds the set outlet pressure, the increased force overcomes the spring tension, causing the diaphragm to move upward and close the valve. This action prevents high pressure from reaching the downstream side, ensuring the system remains protected.

Self-Regulating Design: During periods of low or no water demand downstream, the PRV stays closed to prevent gradual pressure buildup on the inlet side. The valve maintains consistent downstream pressure, whether during dynamic or static conditions.

This dual control mechanism allows PRVs to effectively manage fluctuating main pressures, ensuring steady and safe water flow while protecting appliances, fixtures, and plumbing systems from damage caused by excessive pressure.

How does a hydraulic pressure reducing valve work?

Hydraulic pressure reducing valves operate similarly to water PRVs but are built to handle hydraulic fluids under higher pressures. A pilot-operated mechanism is often used for precise control, ensuring consistent pressure in hydraulic machinery and industrial applications.

Different applications call for various types of pressure reducing valves (PRVs), each tailored to specific system requirements. Here are the most common types:

• Single-Stage PRV: Designed for straightforward pressure reduction, suitable for simple systems.
• Double-Stage PRV: Provides enhanced pressure stability, making it ideal for complex or high-demand systems.
• Direct-Acting PRV: Compact and efficient, often used in residential plumbing applications.
• Pilot-Operated PRV: Ensures precise pressure control, commonly used in high-pressure or industrial setups.
• Automatic PRV: Automatically adjusts pressure settings based on flow requirements, ideal for dynamic systems.
• Spring-Loaded PRV: A versatile option for general plumbing and HVAC systems, using a spring mechanism to control pressure.
• Bypass PRV: Redirects excess pressure around the main system to prevent overloading.
• Temperature and Pressure Relief Valve (T&P Valve): Protects water heaters by releasing pressure and temperature buildup to avoid damage or safety risks.
• Adjustable PRV: Allows users to customise pressure settings, offering flexibility for various applications.

Each PRV type serves a unique purpose, ensuring efficient pressure control and safeguarding plumbing systems.

Follow these steps to install a PRV valve correctly:

1. Choose the Right Location: Ensure easy access for maintenance.
2. Shut Off Water Supply: Turn off the main valve to prevent leaks.
3. Measure Pressure: Check system pressure using a gauge.
4. Select the Correct PRV: Match the valve to your system's specifications.
5. Prepare the Area: Clean and deburr the pipe ends.
6. Cut the Pipe: Create space for the PRV in the pipeline.
7. Apply Teflon Tape: Ensure leak-free connections.
8. Install the PRV: Securely connect the valve to the pipeline.
9. Tighten Connections: Avoid over-tightening to prevent damage.
10. Check Pressure Settings: Adjust the valve to the desired pressure.
11. Turn On Water Supply: Gradually restore water flow.
12. Test Functionality: Verify proper operation and pressure levels.

What is a water pressure reducing valve good for? Using a PRV in residential, commercial, or industrial water systems offers numerous advantages, including:

• Prevents Damage to Plumbing Systems: Reduces excessively high water pressure from mains, tanks, or boosted supplies, minimising the risk of pipe bursts, leaks, and accelerated wear on plumbing components.
• Reduces Noise and Vibrations: Prevents water hammer, slamming sounds, and pipe vibrations during valve or tap shut-offs, especially when feeding appliances like washing machines or showers with lower pressure ratings.
• Stabilises Water Flow: Provides a consistent and comfortable flow rate across various water usage scenarios, ensuring steady performance even in multi-story buildings or systems with fluctuating supply pressure.
• Improves Energy Efficiency: Lowers water pressure, which helps heating systems work more efficiently. Approximately 30% of household water usage involves heating, so reduced pressure leads to significant energy savings.
• Conserves Water and Reduces Waste: Decreases water flow at high pressure, preventing unnecessary water wastage and lowering utility bills. Many homes and businesses do not require very high water pressure for regular activities.
• Enhances System Longevity: Protects pipes, fixtures, and connected devices from the wear and tear caused by high-pressure water, extending their lifespan and reducing maintenance requirements.
• Offers Static Pressure Control: Prevents gradual pressure creep during low-demand or no-flow conditions, maintaining safe and manageable pressure levels in the system.
• Promotes Efficient Multi-Unit Regulation: Helps regulate pressure between floors or units in larger or older buildings with gravity-fed or boosted supplies.
• Minimises Maintenance Costs: Protecting the plumbing system from pressure-related damage reduces the frequency and cost of repairs over time.

If your current system experiences issues like noisy pipes, excessive water use, or uneven flow, installing a PRV can address these problems effectively. Proper maintenance and periodic inspections of PRVs can further ensure their long-term performance and reliability.

Adjusting a PRV at home is a simple task. Follow these steps:

• Locate the Adjustment Screw or Dial: Identify the screw or dial on the valve, usually located on the top or side.
• Loosen the Locknut: If the valve has a locknut, loosen it to access the adjustment mechanism.
• Adjust the Pressure: Turn the screw clockwise to increase pressure and counterclockwise to decrease pressure.
• Tighten the Locknut: Secure the locknut after making adjustments to maintain the new settings.
• Recheck the Pressure: Use a pressure gauge to ensure the valve is set to the desired level.

For safety and accuracy, make adjustments gradually and test the pressure after each small turn.

Recognising the signs of a malfunctioning pressure reducing valve early can help prevent further damage to your plumbing system. Look out for the following:

• Fluctuating Water Pressure: Inconsistent valve performance can cause water pressure to vary unpredictably.
• Low Water Pressure: Insufficient flow throughout the house may indicate a failing PRV.
• High Water Pressure: Excessive pressure can damage appliances, fixtures, and pipes.
• Water Hammer or Banging Noises: Pressure surges can lead to loud pipe noises during usage.
• Leaks Around the Valve: Leaks suggest wear, improper installation, or a failing valve seal.
• Inconsistent or No Pressure Reduction: This leaves your system vulnerable to pressure surges.
• Noisy Valve Operation: Unusual sounds may point to internal blockages or worn components.
• Difficulty Adjusting Pressure Settings: Resistance or inability to adjust the valve indicates a malfunction.
• Increased Water Consumption: Ineffective pressure control may result in excessive water use.
• Visible Corrosion or Damage: Rust, cracks, or other physical signs of wear compromise valve performance.

If you notice one or more of these issues, it’s crucial to address them promptly. A damaged PRV can lead to costly repairs and inefficiencies in your plumbing system, so consider consulting a professional for inspection, maintenance, or replacement.

For guides on troubleshooting common plumbing issues or tools you may need, such as how to calibrate a thermometer or how a check valve works, explore our comprehensive resources and expert advice online. Browse our online catalogue today for quality products and enjoy fast, dependable delivery across Australia. For more details, visit our Delivery Information page.