What is the difference between a Volumiser and a Buffer Tank and do I need one?
Posted on March 22nd, 2026
Volumisers & Buffer Tanks: What They Are and Why Your Heat Pump Might Need One
When you’re exploring air source heat pumps, you might come across terms like volumiser or buffer tank. They sound technical, but their purpose is simple: they help your heat pump run smoothly, efficiently, and reliably.
At WYGS, we design every system carefully so your home stays warm, your running costs stay low, and your heat pump lasts for years.
🔵 What Is a Volumiser?
A volumiser is a small, insulated vessel (usually 20–50 litres) that adds extra water volume to your heating system.
- Keeps water flowing smoothly
- Prevents short cycling
- Reduces wear on the compressor
- Improves efficiency and comfort
When we use a volumiser:
- Smaller radiator systems
- Pipework with low water volume
- Systems needing stable flow rates
- Homes where a simple, efficient setup is ideal
💙 What Is a Buffer Tank?
A buffer tank is a larger vessel (50–200 litres) that provides both extra water volume and hydraulic separation. This helps different parts of your heating system work at their own pace without affecting the heat pump.
- Smooths temperature changes
- Helps during defrost cycles
- Supports multiple heating zones
- Balances underfloor heating and radiators
When we use a buffer tank:
- Homes with underfloor heating + radiators
- Properties with multiple heating zones
- Systems needing different flow rates
- Larger or more complex heating layouts
🔵 Volumiser vs Buffer Tank – Simple Comparison
| Feature | Volumiser | Buffer Tank |
| Size | 20–50L | 50–200L |
| Purpose | Add water volume | Add volume + hydraulic separation |
| Best for | Radiator systems | UFH + radiators, multi‑zone homes |
| Cost | Lower | Higher |
| Benefits | Prevents short cycling | Smooths system, supports mixed circuits |
💙 Which One Do You Need?
Most homes only need a volumiser. Homes with underfloor heating or multiple zones often benefit from a buffer tank.
At WYGS, we carry out a full heat loss calculation, check your radiators, pipework, and heating layout, and design the system that gives you the best efficiency, lowest running costs, and longest heat pump lifespan.
🔵 Why WYGS Designs It Properly
- We follow MCS design standards
- We use high‑quality components
- We ensure correct flow rates and water volume
- We build systems that last
It’s all part of delivering a premium, reliable installation you can trust.