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Radiator Valves Explained: Why You Need Them and How to Choose
Choosing a new radiator? Don’t forget the valves. These small fittings help connect your radiator to your central heating system and control the flow of hot water. Choosing compatible valves when ordering your radiator can help you avoid missing parts on installation day.
Do Radiators Come with Valves?
Don’t assume valves are included with your new radiator or heated towel rail. Check the product description and what’s included before ordering.
If valves are sold separately, you’ll need a suitable set for your radiator and pipework. If you’re replacing an existing radiator, ask your plumber whether your current valves can be reused.
What Do Radiator Valves Do?
Radiator valves regulate the flow of hot water through a central heating radiator.
A typical installation has a control valve at one end and a lockshield valve at the other. The control valve lets you adjust the heat, while the lockshield helps balance water flow through the heating system. Check the contents of your chosen valve set to see whether both are included.
How Does a Thermostatic Radiator Valve Work?
A thermostatic radiator valve, often called a TRV, automatically adjusts hot water flow in response to the temperature around it.
Inside a conventional TRV head is a temperature-sensitive element. As the surrounding air warms up, this element acts on the valve mechanism to reduce water flow. When the air cools, the valve allows more hot water through again.
This helps maintain a comfortable room temperature while the central heating is running. A conventional TRV does not switch the boiler on by itself.
What Do the Numbers on a Radiator Valve Mean?
The numbers represent different temperature settings, rather than the temperature of the radiator itself. Higher numbers generally mean a warmer target room temperature.
The exact temperatures vary between models, so check the manufacturer’s instructions rather than assuming every valve uses the same scale.
Does Turning a TRV to Maximum Heat the Room Faster?
Not necessarily. If the room is cold enough, the valve may already be fully open at your normal setting. Turning it to maximum raises the target temperature; it does not make the boiler water hotter.
Choose a comfortable setting and give the room time to warm up.
Why Does My Radiator Cool Down When the Heating Is On?
Your room may have reached the temperature selected on the TRV. The valve then reduces hot water flow, allowing the radiator to cool.
Keep the thermostatic head clear of curtains and furniture so it can sense the room temperature accurately.
Straight, Angled and Corner Radiator Valves Explained
Valve shape describes how the pipework connects to the radiator. Choose it by checking both the pipe direction and the position of the radiator’s connections.
| Connection Shape | Connection Layout | What to Check |
|---|---|---|
| Straight | Connects the pipe and radiator in a straight line. | Whether the pipe and radiator connection line up directly. |
| Angled | Changes the flow direction by 90 degrees. | Whether the installation needs a right-angle connection. |
| Corner | Provides a right-angle connection with a different valve-head position. | Whether the head position suits the wall-fed pipework and available space. |
What Is a Cross Head Radiator Valve?
A cross head radiator valve has a cross-shaped handle, often chosen for its traditional appearance.
“Cross head” describes the handle design, while “straight”, “angled” and “corner” describe the connection shape. Many cross head valves are manual, so check the product specification if you want thermostatic control.
How to Tell If a Radiator Valve Is Open or Closed
The method depends on the type of valve.
Manual and Cross Head Valves
Most manual valves open when turned anticlockwise and close when turned clockwise. Turn the handle gently and follow the manufacturer’s instructions.
Thermostatic Radiator Valves
A TRV’s dial shows its temperature setting, rather than whether water is currently flowing. Even at a higher setting, the valve may close when the room reaches the selected temperature.
The snowflake symbol usually means frost protection. It is not the same as fully isolating the radiator, because the valve can open again if the temperature drops.
Lockshield Valves
A lockshield usually has a protective cap covering the adjustment mechanism. It is used for balancing the heating system, rather than everyday temperature control.
Avoid changing its setting simply to make the room warmer or cooler. For radiator removal, ask your plumber to isolate the radiator correctly.
What to Check Before Buying Radiator Valves
Before placing your order, confirm:
- Whether your radiator includes valves.
- Whether you want manual or thermostatic control.
- Which connection shape suits your radiator and pipework.
- Whether the pipe and radiator connection sizes are compatible.
- Whether the set includes a lockshield valve.
- Which finish complements your radiator and other fittings.
Browse our radiator valve collection to complete your installation. If you’re unsure which type to choose, confirm the connection details with your plumber before ordering.