TRV and Lockshield: Essential Guide to Radiator Valve Types

Radiator valves make a real difference when it comes to managing hot water flow from your boiler to each radiator at home. They affect your comfort and the efficiency of your heating, so knowing what they do actually matters.

Picking the right valve means thinking about each room’s heating needs. Usually, that’s measured in BTUs or Watts. The right heat output keeps things comfortable and helps you save energy.

There are three main types of valves out there, all designed for different ways you might want to control your heating and how you install things.

The Automatic Valve (Thermostatic Radiator Valve or TRV)

A thermostatic radiator valve, or TRV, is a pretty clever little device. You just set the dial to your preferred warmth, and it does the rest, maintaining that temperature for you.

How TRVs Function

The valve has a temperature-sensitive mechanism inside. It tracks the air temperature in your room and, once you hit your chosen setting, the valve cuts down the hot water flow to the radiator. If things cool off, it opens up again. All this happens without you having to fiddle with it.

Setting Up Different Comfort Zones

TRVs let you create different temperature zones around your home. For example:

• Bedrooms: Lower settings (2-3) for cooler, better sleep

• Living areas: Higher (3-4) for comfy evenings

• Bathrooms: Max out (4-5) for toasty towels

What You Get When Purchasing

When you buy a TRV set, you get the thermostatic head with the dial, a matching lockshield valve, and all the fittings you need. Everything’s ready for installation.

Mechanical vs Smart Technology

Standard TRVs just use mechanical temperature sensing—no electricity, no Wi-Fi, no apps. That’s pretty straightforward. Smart TRVs, on the other hand, have digital controls and can connect to your phone or home network if you’re into that kind of thing.

The Balancing Valve (Lockshield Valve)

The lockshield valve sits at the other end of your radiator, opposite the TRV. It’s got a plastic cap you can pop off to reach the adjustment part underneath.

Primary Function

This valve controls how much water leaves each radiator and heads back to your boiler. By restricting the return flow, it helps make sure hot water gets around to every radiator, even the ones tucked away in far corners of the house.

How It Works

Picture your heating system as a web of pipes. If you don’t control the flow, the radiators closest to the boiler hog all the hot water, leaving the others chilly. The lockshield valve adds just the right resistance to balance things out.

Professional Setup Required

Usually, a heating engineer will set these up when installing or servicing your system. Once set, it’s best not to mess with them. If you do, you might throw off the whole system’s balance and lose efficiency.

The Manual Valve

Manual valves are as simple as it gets. You just grab the valve head and turn it by hand to control the heat.

How Manual Valves Function

Turning the head opens or closes the valve inside. Turn it anticlockwise to let more hot water in, or clockwise to restrict the flow and cool things down.

Key Characteristics

• No automatic features – it stays exactly where you put it

• Complete manual control – you’re in charge of every adjustment

• Fixed positioning – keeps the heat steady until you change it

• Simple operation – just twist the head to your liking

Common Applications

Manual valves are super handy for certain spots:

Location Why It Works Bathroom towel rails Just need basic on/off control Utility rooms Simple adjustment does the trick Guest bedrooms Easy for occasional use

You get straightforward, no-nonsense control with these. Sometimes, that’s really all you need.

By the way, if you’re after any of these valves, radiatorstore.uk/store has a pretty wide selection. We stock everything from basic manual valves to TRVs and lockshields, so you’ll find something that fits your setup.

And if you care about the look as much as the function, we do a bunch of finishes—brushed brass, gun metal, bronze, and honestly, quite a few more. It’s nice when your valves match your radiator or your room, right?

Common Questions and Answers

How Do TRVs Differ from Lockshield Valves?

TRVs and lockshield valves do completely different jobs. TRVs have a temperature sensor and adjust water flow based on how warm the room is. You can tweak the setting whenever you want.

Lockshield valves, though, control how much water leaves each radiator. They help balance the whole system, and once you’ve set them, you shouldn’t need to mess with them again.

Most radiator valve sets come with both: TRV on one end for temperature, lockshield on the other for balance.

How Can You Balance Radiators Properly Using Both Valve Types?

Balancing helps your radiators heat up at similar speeds. Start with all lockshields wide open and TRVs on max.

Here’s how I’d do it:

1. Turn the heating on

2. See which radiators get hot first (they’re usually closest to the boiler)

3. Gradually close the lockshield on those fast-heating ones

4. Wait about 20 minutes and check all the radiators

5. Tweak lockshields until everything feels even

Make a note of where each lockshield ends up, so you can reset them if needed. You don’t need to adjust TRVs during this—just leave them open while balancing.

What Maintenance Do Thermostatic Radiator Valves Need?

TRVs are pretty low-maintenance, but it helps to give them a bit of attention now and then. Once a month, turn the valve from minimum to maximum a few times to keep it moving freely.

A few quick tips:

• Dust off the sensor head now and then

• Check pipe joints for any loose spots

• Test how it responds when you start heating for the season

• If you’ve got an electronic model, swap out the batteries when needed

Just wipe the valve head with a damp cloth—no harsh chemicals, or you could damage the sensor.

Can Lockshield Valves Replace Thermostatic Valves for Manual Control?

Technically, you could use a lockshield for manual control, but honestly, that’s not what they’re for. They’re meant for balancing, not day-to-day adjustments.

If you want regular manual control, go for a proper manual valve. They’re easier to use, let you fine-tune the flow, and have clear markings. Lockshields usually need a tool to adjust and don’t show you the temperature.

If you prefer hands-on control over automatic regulation, pick manual valves instead of trying to use lockshields for something they’re not made for.

How Should You Set TRVs for Best Energy Efficiency and Comfort?

Set TRVs to match how you use each room. Living rooms usually feel good at 3-4, bedrooms at 2-3.

Some energy-saving ideas:

• Turn settings down a notch in rooms you’re not using

• Don’t crank TRVs to max unless you really need it

• Completely close TRVs in unused rooms

• Try not to cover TRVs with curtains or furniture

Oh, and always leave at least one radiator without a TRV (or keep one TRV fully open) while your boiler’s running. That helps avoid pressure issues in your system.

What Steps Fix Unresponsive or Stuck TRV Problems?

Stuck TRVs usually happen when the internal pin seizes up. First things first: turn off your heating and let the radiator cool down all the way.

Here’s what you can try:

1. Remove the TRV head—just unscrew or unclip it, depending on your model.

2. Check for a small metal pin inside the valve body.

3. Give the pin a gentle tap with a small hammer or even the back of some pliers.

4. Work the pin up and down, back and forth, until it starts moving smoothly again.

5. Pop the TRV head back on and see if it’s working now.

If that pin still refuses to budge, try a bit of penetrating oil and give it half an hour before having another go. Sometimes, though, it’s just time to swap out the whole TRV for a new one—no shame in that.

We’ve got a whole range of valves at in our store if you’re looking for a replacement or fancy an upgrade. There’s a bunch of finishes too—brushed brass, gun metal, bronze, and honestly, quite a few more. Why not pick a style that actually matches your space?