How to balance your radiators: a step-by-step guide

With winter on the way, it’s good to address any heating issues you might have, before you have them! This includes making sure your radiators are working efficiently and effectively. 

When you turn your central heating system on for the first time, all your radiators should heat up to the same temperature at the same speed. If they don’t, and you find some are cooler than others, you might need to balance your radiators. 

If you’re not comfortable with DIY, we would recommend getting this done by a specialist. There are a lot of different elements to think about – such as the size of your radiators, pipework, radiator valve layout, and so on. 

But, as this is a common problem at the beginning of winter, we’ve created this guide for those more experienced DIYers among you. Find out how to  balance your radiators with minimum fuss (and get cosy no matter which room you’re in). 

What does balancing radiators mean? 

It simply means adjusting the radiator valves, which control how much water flows through each of your radiators, so they heat up equally, at the same speed. 

Why would you need to balance a radiator? 

Let’s say the radiator in your hallway gets almost too hot to touch straight away, but the one in your living room only manages to get lukewarm. That’s a sure sign your radiators need balancing. 

It just means the hot water isn’t being evenly distributed. That’s a major issue with winter on the way! 

Balance or bleed: what’s the difference?  

You’ll know when your radiators need bleeding because they’ll make a noise when coming on, or they won’t heat up properly at the top. This is caused by trapped air, which needs releasing. 

It’s an easy fix, using a radiator key. Here’s our step-by-step guide on how to bleed your radiator, or you can simply watch one of our OVO engineers guide you through the steps in this video. 

Balancing your radiator, on the other hand, means you’ll need to allow more hot water to flow to the colder radiators – and out of the ones that are too hot. 

If you find your radiators aren’t working properly, but you’re not sure if they need bleeding or balancing, your best bet is to do both! Start with bleeding your radiators, and if there are still issues, then you can balance them. 

What tools will you need to balance a radiator? 

Make sure you have these tools ready before you start:

• Radiator bleed key
• Lockshield valve key or adjustable spanner
• Screwdriver
• Digital thermometer or multimeter with thermometer

What kind of radiator valves do you have?

Before you begin, here’s a quick rundown of the radiator valves you may find in your home:

Manual valve

This is the original type of radiator valve, which only has 2 positions – on or off – so the only choice you have is to allow water to flow, or not. It usually has a plain, round metal top, which can be twisted on or off. 

Thermostatic radiator valve (TRV)

Most homes these days have TRVs on their radiators, which look like dials with numbers on. You can use these dials to set the temperature you’d like your radiator to be. 

Lockshield valve

This type of valve is smaller, and covered with a domed plastic hood. Some have a screw through the hood that must be taken out before you can take off the plastic hood. You’ll need pliers or a grip of some kind to take off the hood. Underneath looks like the end of a flat-head screwdriver. 

All radiators will have either a manual or TRV on the inlet, and a lockshield valve on the outlet.

Balancing radiators: step-by-step guide

Ok, so you have your tools. Let’s go!

1. Bleed your radiators

As mentioned above. It’s a good idea to bleed your radiators first. That way you’ll get rid of trapped air and your radiators should heat up equally all over. 

Then you’ll be able to get an accurate temperature reading – so you’ll know which radiators need more water, and which radiators need less. 

2. Turn off your central heating

Make sure it’s completely turned off, and wait for the radiators to cool down. 

3. List all the radiators in your home

You can do this on a piece of paper, to refer to later.

4. Open your radiator valves

Once your radiators are completely cold, open both radiator valves on either side of every radiator. You can do this by turning them anti-clockwise. 

Manual valves and thermostatic radiator valves (TRVs) are easy to open: just twist them by hand. For lockshield valves (the ones with the plastic hoods), remove the hood and turn the metal valve anti-clockwise with a lockshield valve adjuster or your adjustable spanner. 

5. Identify the fastest heating radiator

Now turn the heating back on. With your list in hand, walk around your home to find out which radiator heats up first. Hint: it’s most likely to be the one nearest your boiler. 

You might want to ask family members or a friend to help you with this, especially if you have a big house! As you go, jot down the order your radiators heat up on your list. 

6. Turn the heating off and then on again

Yes, it sounds like a bit of a faff, but it’ll be worth it! Turn the heating off, and wait for all the radiators to cool down until they’re completely cold. Then turn your central heating back on again (nearly there!).

7. Turn the lockshield valve on the fastest-heating radiator

Go to the radiator that you identified as the fastest to heat up, and turn the lockshield valve until it’s completely closed. Then open it by a quarter of a turn. 

8. Take temperature readings

• Once the radiator is hot, take a temperature reading where the pipework meets the floor or wall (on the lockshield valve side). Note this down. 
• Then, take the temperature of the pipework on the manual/TRV side. Note this down. 
• Slowly open the lockshield valve, until there’s a 12C temperature difference between the 2 valves.

TIP: It’s vital that you leave a few minutes after each adjustment of the radiator valves to allow the temperature to change. 

9. Repeat with the other radiators

Once you’ve balanced your first radiator so there’s a precise difference of 12°C between the 2 valves, it’s time to move onto the rest of your radiators. Do this in the order they heated up, by checking your list. 

While balancing your radiators, you’ll find that the amount the lockshield valve needs to be opened relates directly to the distance of the radiator from your boiler. When it comes to your last, slowest-heating radiator, you might find the lockshield valve needs to be opened completely.

Once you’ve done this for all your radiators, balance in your home will be restored, and all your radiators will pump out heat just as they should. Well done! 

How long does it take to balance radiators?

Admittedly, it’s not quite as quick a task as bleeding radiators, so the whole process might take a few hours. But most of the time is spent waiting for your radiators to heat up and cool down. 

So put the kettle on and relax in the knowledge that very soon your home will be cosy through and through! 

When to balance your radiators

It’s advisable to bleed and balance your radiators at least once a year, at the beginning of the cold season. Other times when your heating system may need balancing again are:

• After the removal of radiators for decorating 
• After the replacement of radiators and valves
• After any flushing/cleansing activities
• After alterations to the heating system
• After the replacement of the central heating pump
• After the replacement of the boiler