Pressure Relief Valve (PRV) vs Pressure Reducing Valve (PRDV)

Pressure Relief Valve vs Pressure Reducing Valve

What’s the Difference — and Why Joven Recommends Both

When installing an electric storage water heater, many homeowners believe that a pressure relief valve and a pressure reducing valve perform the same function.

At Joven, we often see this misunderstanding lead to unnecessary leaks, premature tank failure, and avoidable service calls.

In reality, these two valves serve very different purposes, and understanding the difference is essential to protecting your water heater, your plumbing system, and your peace of mind.

What Is a Pressure Relief Valve?

Every Joven electric storage water heater is equipped with a pressure relief valve (also known as a temperature & pressure relief valve). It is shipped together in your box of heater. DO NOT switch it to any other brands as this will void the warranty of the heater entirely.

Its Role

The pressure relief valve is a safety device designed to:

  • Release water only when pressure or temperature reaches a dangerous level

  • Prevent tank rupture or structural damage

  • Act as a last line of defense in abnormal conditions

Important to Know

  • It is normally closed

  • It does not regulate daily water pressure

  • It should rarely operate under normal conditions

Think of it as an emergency safety valve, not a pressure control solution.

What Is a Pressure Reducing Valve?

A pressure reducing valve (PRDV) is installed on the cold-water supply line before water enters the heater.

Its Role

The PRDV:

  • Continuously reduces high incoming mains pressure

  • Maintains a safe and stable operating pressure

  • Protects the inner tank, fittings, and valves from constant stress

Unlike a relief valve, a PRDV works all the time, not just during emergencies.

Key Differences at a Glance

Function Pressure Relief Valve Pressure Reducing Valve
Main purpose Emergency safety Daily pressure control
Operates during normal use ❌ No ✅ Yes
Regulates incoming water pressure ❌ No ✅ Yes
Prevents long-term pressure damage ❌ No ✅ Yes
Required on Joven heaters ✅ Yes ✅ Strongly recommended

The Most Common Misconception We See

“My Joven water heater already has a pressure relief valve, so I don’t need a pressure reducing valve.”

This is incorrect.

A pressure relief valve:

  • Activates only after pressure becomes excessive

  • Is not designed to operate frequently

  • Does not protect the heater from constant high pressure

If your home’s water pressure is consistently high, the heater is under stress every single day — even if the relief valve never opens.

By the time the relief valve discharges water, wear and damage may already be occurring internally.

Why Relying on a Relief Valve Alone Is Risky

From Joven’s service experience, repeated relief valve discharge often leads to:

  • Persistent dripping or leakage

  • Energy and water wastage

  • Accelerated valve wear

  • Reduced tank lifespan

A relief valve is a safety backup, not a pressure management system.

Joven’s Recommended Best Practice

For optimal safety and durability, Joven recommends using both valves together:

✔ Pressure Reducing Valve

Installed at the cold-water inlet to:

  • Regulate pressure continuously

  • Protect the heater from long-term stress

  • Ensure stable heating performance

✔ Pressure Relief Valve

Installed on the heater as:

  • A mandatory safety component

  • Protection against abnormal pressure or temperature events

This combination ensures:

  • Longer heater lifespan

  • Stable water temperature

  • Reduced maintenance issues

  • Peace of mind for homeowners

Why This Matters in Singapore Homes

In Singapore, water pressure can vary significantly depending on:

  • Building height

  • Floor level

  • Plumbing layout

Requests to reduce pressure at the main supply may not always be approved, especially in high-rise buildings.

That’s why installing a dedicated pressure reducing valve at the water heater is often the most effective and practical solution.

Our Advice to Joven Customers

  • Always engage a licensed plumber

  • Never remove or bypass safety valves

  • Use a pressure reducing valve to protect your investment

  • Treat water pressure control as preventive protection, not an afterthought