Radiators play a really important role in keeping our homes warm and cosy, especially during the colder months. They work by spreading heat from a central boiler throughout the house, sending hot water to each radiator. This way, each room or zone in your home stays nice and comfortable.

The valves on your radiators have the crucial job of ensuring the correct amount of hot water flows in and out of your radiators to make sure that your room is kept at the temperature you desire. In this article, we take a brief look at the different types of radiator valves that exist and then focus specifically on the role of the Lockshield Valve on your radiator. We explain what it is, what its purpose is and how to open one if you need to.

What Are The Main Types of Radiator Valve?

On a typical radiator you would typically find one main valve (either manual, TRV, or smart) on one side of the radiator and a Lockshield Valve on the other. Each valve serves a unique function in controlling and balancing the heat output from radiators. Here is a brief rundown of each type:

Manual Radiator Valve

These are the most basic type and while still common on older radiators, they are a rare find on modern designs. Typically located on the flow pipe, they are operated by manually twisting the valve to adjust the water flow into the radiator. They usually have a double-ended arrow on the top of the cap with plus and minus signs to indicate how open or closed the valve is. The more you open the valve, the more hot water can flow into the radiator when the central heating is turned on. They’re simple to use but don’t automatically adjust to temperature changes.

Thermostatic Radiator Valves (TRVs)

If you own a new-build home or have modern radiators in an older property, you will likely have a thermostatic valve on your radiators. TRVs allow you to set a desired temperature for each radiator, and the valve automatically adjusts the flow to maintain that temperature. They generally have a twistable, stout cap with numbers from 0-5 on. Each number correlates to a certain temperature (1 being the coldest and 5 being the hottest). 0 indicates the valve is completely closed (off) and the frost setting (indicated by an asterisk (*) or snowflake symbol is normally used to prevent your pipes from freezing if you are away from home during extremely cold weather.

Oliver Osmore, Managing Director of Maintracts Services adds:

“Many of our customers are shocked to find out that TRVs do not directly control the temperature of the radiator. Instead, they work by detecting the temperature of the room around the radiator and valve and react accordingly. If the temperature of the room drops to below the temperature you have set, the valve will automatically open to allow more hot water into the radiator to raise the temperature to where it needs to be. When the room reaches or exceeds the set temperature, the opposite will occur.”

TRVs are becoming increasingly popular as they save energy by only heating rooms when needed. For example, you can completely turn off the radiator in a guest bedroom until you have a visitor come to stay or lower the temperature in a bedroom at night if you prefer a lower temperature while you sleep. For a greater understanding of TRVS, view our guide to understanding Thermostatic Radiator Valves.

Smart Radiator Valves

These are newer, more advanced valves that connect to smart home systems, allowing you to control radiator temperatures via a smartphone app. They offer precise control and energy efficiency by adjusting based on room usage and schedule.

Lockshield Valves

Often found on the opposite side of the radiator from the main valve, Lockshield Valves control the flow of water leaving the radiator, helping to balance the system. They’re usually adjusted once and left alone to keep all radiators heating evenly. Read on to find out the details regarding this specific radiator valve.

Each type of valve offers different levels of control and energy efficiency, so choosing the right one depends on your heating needs and how much control you want over individual room temperatures.

What Is A Lockshield Valve On A Radiator?

A Lockshield Valve is the component on a radiator that needs to be adjusted when balancing radiators. It helps to balance out each radiator within your central heating system to ensure they all heat up at the same rate.

The Lockshield is typically located on the opposite side of radiator from the main (on/off) valve. This valve is typically covered with a plastic cap because it is designed to be adjusted only once (or very rarely) to help balance the heating system. Unlike the main radiator valves, which are frequently adjusted to control the radiator’s heat output, the Lockshield Valve is set to control the amount of water flowing out of each radiator to balance heat distribution across all radiators in the central heating system.

Once adjusted, the plastic cap acts as a protective cover, preventing accidental changes. The cover prevents everyday adjustments and helps keep the system balanced, as changing the Lockshield’s settings can disrupt the system’s overall efficiency. On top of all of that, the cap is much nicer to look at!

What Is The Purpose Of A Radiator Lockshield Valve?

The Lockshield Valve serves a few important purposes that are crucial in the efficient running of a heating system:

Balancing the heating system: The primary purpose of a Lockshield Valve is to balance a (and maintain a balanced) heating system, ensuring that all radiators heat up evenly throughout the home. By adjusting the flow rate of water leaving each radiator, the Lockshield Valve helps distribute heat evenly across all radiators, including those farthest from the boiler.
Controlling water flow: The Lockshield Valve regulates the amount of hot water that exits the radiator. By setting it to a specific position, it limits how much hot water flows out, preventing radiators closer to the boiler from overheating and allowing radiators further away to receive adequate heat.
A means of draining the system: Sometimes, a professional plumber may need to drain all the water out of your heating system in order to perform a repair (such as to remove radiator sludge, powerflush, or mend a leak) or conduct maintenance. On one of the radiators in your home, there will be one Lockshield Valve that looks a bit different from the rest – this valve will contain a drain-off, that is designed to open up and allow the water to be drained from your system.

Improving efficiency: A well-balanced system prevents the boiler from overworking, which can improve overall efficiency and reduce energy consumption. When all radiators reach their set temperatures at a similar time, the system runs more smoothly, saving on heating costs.
Minimising noise: In a properly balanced system, water flows smoothly through each radiator, helping to reduce or eliminate common issues like banging or gurgling sounds caused by uneven flow.

How To Open A Lockshield Valve

There will come a time when you, or a professional plumber will need to open a Lockshield Valve on one or all the radiators in your home. It could be that some of your rads are not heating up as much as the others and adjusting (very slightly) the Lockshield Valve on certain radiators will help distribute the heat more evenly. Or it may be that after bleeding air from a radiator or performing other maintenance, your radiator’s heating has been affected and a tweak of the Lockshield Valve may help to restore the proper water flow to get them heating evenly again. Whatever the reason, here’s how a qualified plumber would go about opening a radiator Lockshield Valve:

When opening a Lockshield Valve, you’ll need a few simple tools and a careful approach. Here’s a step-by-step guide:

Locate the Lockshield Valve

remember, this is usually covered with a plastic cap and located on the opposite side of the radiator from the main valve. Gently pull off the cap to reveal the valve stem.

Make sure you have an adjustable spanner, a wrench, or a radiator key to hand

to adjust the valve (which one you use will depend on the type you have).

Turn the valve slowly in an anticlockwise direction to open it.

Make small, gradual turns, typically a quarter-turn at a time, as even small adjustments can affect the radiator’s heat balance.

Check the radiator’s heat

after each adjustment, wait a few minutes to see if the radiator heats up more effectively. This helps you find the right setting without opening the valve too much.

Avoid over-opening

opening the valve fully can upset the balance of your heating system, so it’s best to open it only as much as needed.

Replace the cap!

Once you’ve made the adjustments, put the plastic cap back on to prevent accidental changes.

Top tip:

If you’re balancing multiple radiators, make minor adjustments to each radiator’s Lockshield Valve and test the results to maintain an even heat distribution throughout the system.

There you have it, the Lockshield Valve plays a crucial role in maintaining a balanced and efficient heating system. By carefully adjusting these valves, you can ensure all your radiators heat evenly, improve the efficiency of your system, and reduce energy consumption. Regularly checking the settings and making minor adjustments as needed can help keep your home comfortable and your heating system running smoothly.

For ongoing maintenance, make sure to check that the Lockshield Valves are correctly set after any major repairs or radiator adjustments, and always replace the protective plastic cap after making changes. If you’re unsure or the system isn’t performing as expected, it’s always a good idea to call a professional plumber, like the team at Maintracts Services, to ensure everything is properly balanced. Keeping an eye on your radiator valves can help you get the most out of your central heating and enjoy a warm, cosy home throughout the year.

If you need a professional to help with radiator issues or heating hiccups, you know where we are.