When installing an electric storage water heater, many homeowners believe that a pressure relief valve (PRV) and a pressure reducing valve (PRDV) 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 (PRV)?
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 (PRDV)?
A pressure reducing valve (PRDV) is installed on the cold-water supply line before water enters the heater.
Its Role
The pressure reducing valve (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 (PRDV)
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