- What balancing a radiator entails and why it is important
- Step-by-step guide on the process of balancing radiators
- Required tools for balancing radiators (radiator key, valve adjuster, thermometer, screwdriver)
- Troubleshooting tips should radiators remain unbalanced after following the recommended steps
- The difference between flushing, bleeding and balancing radiators
- How to balance radiators featuring thermostatic radiator valves (TRVs)
- The advantages of balanced radiators (level heat distribution, improved energy efficiency, cost savings)
- The best time to rebalance radiators (on an annual basis, following system adjustments)
- Indicators that radiators require balancing (uneven room temperatures, fluctuating heat-up times)
The ultimate step-by-step guide on how to balance radiators
If you have hot and cold spots on some of your radiators or find that some radiators get warm whilst others do not, then your radiators need balancing.
Now don’t worry because it’s a pretty simple DIY job and in this step-by-step guide on how to balance radiators we’re going to give you all of the information you’ll need on how to get your radiators all fired up and back to their best.
What does balancing radiators mean?
Balancing radiators means adjusting the radiator valves to level the water flow and make sure your radiators heat up at the same speed.
If instead you find that your radiators are cold at the top, you should visit our Bleed A Radiator guide. Or, if you have radiators that are cold at the bottom, you may have a build up of sludge, and should check out our How To Flush A Radiator guide instead.
How to balance radiators
If you are a decent enough DIY-er, simply follow the bulleted steps below to balance your radiators. But if you’ve never been around a heating system before, check out the full guide and you’ll have those radiators balanced in no time.
- Turn off your heating
- Open all your radiator valves
- Turn the heating back on
- Record how fast each radiator heats up
- Turn your heating off and allow it to cool
- Turn the heating back on
- Adjust the first radiator to heat up
- Take your radiator’s temperature
- Take the temperature of the pipework
- Check each radiator on your list
What is the difference between bleeding & balancing radiators?
Balancing radiators
When you balance radiators, you allow more water to flow to the colder radiators and restrict the flow from the radiators that are too hot.
For example, if the radiator in the kitchen heats up quickly but the one in the lounge takes forever, then your radiators need balancing.
Bleeding radiators
Bleeding a radiator means letting the trapped air out of the valve with a radiator key.
If your radiators make noise when the heating is coming on, or if your radiators have cold patches at the top, then they need bleeding.
Do you need to bleed or balance your radiators?
You will do a better job at balancing your radiators if you have bled them first because you will get a more accurate temperature reading.
So, if your radiators are not working properly and you’re unsure whether you need to bleed or balance your radiators, do both! But, make sure you bleed them first.
Balancing radiators in 10 steps
What tools will you need to balance radiators?
- Radiator bleeding key
- Lockshield valve adjuster or adjustable spanner
- Screwdriver
- Digital thermometer or multimeter with a thermometer function
Step 1. Turn off your heating
Make sure all the radiators have been bled (here’s a guide on how to do that). Turn off the central heating and let the radiators cool down, until they are completely cold.
Step 2. Get to know your radiator valves
Find and familiarise yourself with the valves on your radiators. This is a lockshield valve and will usually have a push-on cap, or a cap that is secured with a screw through the top of it. Remove the cap altogether.
Many modern homes will have TRVs – Thermostatic Radiator Valves – attached to most of the radiators on the opposite side from the lockshield valves. A TRV should always be fitted to the inlet on the radiator and the LSV to the outlet.
Step 3. Open all your radiator valves
Open up the valves on every radiator in the house by turning them anti-clockwise. Thermostatic valves or older wheel-head valves can be turned quite easily by hand but the lockshield valve will need a plastic adjuster or a spanner to open it.
Step 4. Check how your heating system heats up
Once all of the valves have been successfully opened, turn the central heating back on and take note of the order in which the radiators heat up.
Radiators nearest the boiler will often get hot first and, if you have a large home with lots of rooms and radiators, it might be an idea to employ a little help to ensure you get the job done properly.
Step 5. Turn off your heating again and allow to cool
Turn the heating off and wait for the radiators to cool down – this may be a good time to practice some yoga or something.
The reason for doing this is because you’re attempting to balance the flow of water and heat through your system.
When you take the temperature of your radiator and valves you’ll be making tiny adjustments. To get the desired effect, it is best to do this from a standing ‘cold’ start.
You close the first radiator’s valve and then open it gradually until you have reached the desired temperature.
If your radiators are not balanced, it will be harder to achieve the desired temperature if they are already on.
Step 6. Go to the first radiator to heat up
When the radiators are cool, turn the heating back on and go to the radiator on your list that began to heat up first.
Turn the lockshield valve clockwise on this radiator until it is closed and then open it again by quarter of a turn.
Step 7. Take your radiator's temperature
When the radiator is nicely warmed up, take a temperature reading at the pipework leading to one of the valves.
Step 8. Take the temperature of the pipework
Next, take a temperature reading at the pipework which leads to the valve on the other side of the radiator, gradually opening the lockshield valve until there is a 12°c difference between that, and the temperature reading from the previous step.
It’s important to ensure that you leave a couple of minutes after each adjustment to the radiator valves in order to allow the temperature to change.
Please note: The temperatures in these images may not necessarily be relevant to your radiator – just ensure there’s a 12°C difference in the temperatures you record at opposite valves, that’s what is important.
Step 9. Check each radiator on your list
Now, check the rest of the radiators in the order on your list. Generally, the further the radiator is from the boiler, the more the lockshield valve will have to be opened. In order to balance your radiators correctly, you may have to have the lockshield valve opened fully at the final radiator.
Step 10. Sit back and relax
Sit back, relax and enjoy the warm and comforting glow of your newly balanced radiators.
Can't balance your radiators?
If you are still suffering with balancing problems or having issues with radiators not heating up properly after following the steps shown then you may have a weak pump and or sludge in the system that is restricting the free flow of hot water around the system.
Check the water coming out when bleeding the radiator, if it’s black then that’s a sign of sludge in the system.
Another telltale sign is cold spots on the bottom-middle section of the radiator. If you suspect your system is blocked up then you may need to add some sludge remover to the system.
Allow this to circulate as much as it can for around 3 days before draining the system completely and then add inhibitor to stop any further corrosion.
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Now it's time to balance your radiators
And there you have it, all the information you need to bring some balance to your radiators and your home heating.
So now you know how to balance a radiator why not let us know how you got on when you did it yourself or if you’re a bit stuck and need to ask any other questions, feel free to leave a comment below or visit us on Instagram, Facebook, Twitter and YouTube.
All the very best for balancing your radiators.
Frequently Asked Questions
It is true that an unbalanced heating system can lead to home radiators staying cold even after bleeding, as a differential in water pressure could lead some radiators to not receive as much hot water as others.
To find out other causes of radiators staying cold after bleeding and potential remedies, explore our blog, Why is my radiator not working after bleeding?
If your home radiators fail to heat up after bleeding, you should first check for issues with your thermostatic radiator valves, such as a stuck pin on the valve. Alternatively, you can perform a radiator power flush or take steps to ensure your heating system is correctly balanced.
If you would like a more detailed insight, consult our blog, Why is my radiator not working after bleeding?
The quickest way to balance central heating radiators is to make adjustments to the lockshield valves attached to them.
If you would like one room to heat up quicker than others, the lockshield valve should be opened slightly more on the central heating radiators within this room. Conversely, for rooms that aren’t used as often, you can close the lockshield valve slightly more on the contained radiators so they don’t heat up as fast, achieving balanced central heating radiators throughout the home.
For an insight into some inspirational central heating radiator designs, meanwhile, take a look at our blog, Top 40 Central Heating Radiator Transformations.
First, switch off your heating system and ensure all your radiators are cooled down. Then, open both valves up on each of the radiators and turn the heating on.
You might have to enlist the help of other family members in the household, but all the radiators need to be examined so you can work out when they heat up and the order in which they heat up.
If you want a particular room to heat up quicker, you should open the lockshield valve on the radiators in that space a touch more.
For the opposite effect in rooms that perhaps aren’t used very often, you can delay the heating process by tightening the lockshield valve slightly more.
More detailed instructions can be found in our Advice Centre blog, Here’s How To Balance Radiators.
What we'll cover...
John Lawless is SEO Manager at BestHeating and a recognised expert in home heating. With over a decade of experience in the industry, he blends technical insight with practical advice on everything from energy efficiency to radiator design, and more. John’s work has featured in national media and leading home & garden publications, and he leads the editorial strategy for the BestHeating Advice Centre – helping homeowners make smarter heating choices with confidence.
18 responses
This is a really great guide John. Thanks for the help. I am sure I will get myself and my home ready for winter now! Haha
Thanks Sherri. I’m glad we can help. Happy heating!
He’s a good looking chap in the picture at the top
Stunner isn’t he? He loves radiators too! He’s just bought about 11 off us!
Right, I don’t understand why do I have to turn the heating off after get the heat up order. If I’ll have to turn it on again to measure the temperature, why do I have to turn it off after they’re warm? It makes no sense to me, what’s the explanation for this? Thank you.
Sorry if I’ve caused some confusion here Daniel, but it’s probably a little safer to go and bleed any radiators that may need bleeding when the radiators are cold. Once the air is out, water will follow, so to save anyone getting scalded, it’s probably safer. I hope that makes sense.
Thanks John. But the bleeding step is the first one (first time I have to turn the heating off) and it does make sense. Turn off, bleed (when it’s cold) and get ready to run like a lunatic through the radiators as they begin to warm up. What I didn’t get is why to turn off on the step 5 / 6.
Ahh right, I get you. Sorry Daniel.
The reason for doing that is because you’re attempting to balance the flow of water and heat through your system.
When you take the temperature of your radiator and valves you’ll be making tiny adjustments. To get the desired effect, it is best to do this from a standing ‘cold’ start.
You close the first radiator’s valve and then open it gradually, until you have reached a desired temperature.
If your radiators are not balanced, it will be harder to achieve the desired temperature if they are already on. Doing it from cold is what our technical specialist (that’s the chap in our CX Team) has advised.
Ok, now makes sense. 🙂 Thank you very much for your time and explanation, John.
Have had an extra rad fitted and now the end one is cold after filling system, bleeding and powering up. So it has become unbalanced for some reason. I need to do as you suggest. The only query I have is should I close all of the lockshields and valves and race round starting from the first, or should they all be open at the ‘start’ of the process? Thanks
Hi Tony, sorry for the late reply.
I’ve been chatting with my colleague about this and we’ve come up with a list for you that may help –
1. Decide on some way to record LSV (LOCK SHIELD VALVE) positions. I use “0” for fully closed and count in 1/4 turns
when opening. Some valves have several turns and some open fully in one turn or less.
2 Record initial LSV positions in case you want to return the system to what it was.
3. Open all radiator Control Valves fully. The Control Valves are the ones with adjustable knobs. Usually a knob taken off
a control valve will fit the LSV. Take off the LSV covers and open all those as well.
4. Turn off the domestic hot water heating circuit, turn off the boiler, and let the system cool.
5. When cooled, turn on the boiler, if necessary turning up the room stat to make it fire up.
6. While the system is warming up, go round all the radiators and feel the flow and return connections.
7. Establish which is flow and return (flow gets warm first).
8. Find which radiators are heating up quickest and which are hardly getting warm. Check at both flow and return
connections. The flow gets hot first, then the radiator body and finally the return pipe.
9. While still warming up, try to turn down the LSVs of the hottest radiators so that the cooler ones “catch up”. This will
give a rough balance (and may be all that was done when the system was installed, if even that).
10. Go round with a thermometer and fill out a ‘Run’ of the table.
11. Work out the temperature drop of each radiator and boiler.
12. Go round again adjusting the LSVs, closing a little those on the radiators with the smallest drop and opening the
coolest a little. The coolest, or biggest temperature drop, radiator LSV should be left wide open otherwise the pump will
finish up working harder than needed.
13. Make sure you have written down the data.
14. Repeat 11 – 13 until you are satisfied that all the radiators are fully hot all over and the differentials are as close as you
can get them.
15. Restore covers to LSVs.
16. If necessary, adjust control valves to reduce room temperatures. This should only be necessary if a radiator is
oversized and is thus over-heating that room, and does not apply if a thermostatic valve is fitted.
17. Reset any thermostatic valves and the room thermostat to give desired room temperatures. The system is now
balanced.
To sum up basically the LSV or lock shield valves (these are the valves on one side of the radiator that have a
cover which must be removed in order to adjust them – but you know that) will be adjusted so that radiators which are getting very
hot or are first on the central heating loop will have there LSV`s turned down to restrict water flow, while
radiators which are having trouble heating will have their valves opened up further, until a balance is achieved
across the system.
I have to say though, this is a basic instruction and if you are still struggling, it may be best to consult an engineer.
It could also be that your boiler isn’t big enough to accommodate another radiator.
I hope this helps.
This is very kind of you to go through the process. I wasn’t expecting such a hasty response and attacked the job soon after posting. I didn’t have a thermometer. I found the first radiators on the system had wide open valves on the LSV’s so went round as water flowed through each and turned them right down. This didn’t impair the output so things were going well. However Murphy’s Law kicked in and the radiator that wouldn’t heat up, still wouldn’t. It worked before the extra radiator was added by the plumber yesterday and the new additional rad works fine. There is heat at the pipe where it enters the rad (from the bottom-old one pipe system)at both ends (the LSV end not so much). I opened the LSV fully but still no flow to the rad. It would seem that there may be an issue with either the LSV or the control valve. Funny but I was thinking of adding on the rad myself but for speed I used a plumber! If I change either valve it will mean draining the system though…so I could have done the whole job! This is now moving away from the subject of balancing the rads. but if you can think of anything else I am all ears! Thanks for the advice to date.
Hi Tony, I’ll have a sit down with my more technical colleagues at some point today and see if we can come up with a solution. I don’t like being stumped, but I’m getting close. Ha Ha! He doesn’t get into the office until late morning, but as soon as he is in I’ll go and pick his brain.
Yes it would seem it logically should be a valve that has decided to seize up. I’ll have to drain it all down to change them! Just what I had decided to get a plumber to do but I am not paying again. It seems pretty simple. I just hope it works! Someone I met said you can create an air lock in the system to avoid having to drain it all down but I can’t recall the detail now!
All the radiators in my (newly moved into) house have TRVs fitted at one end and LSVs fitted at the other. Will the TRVs be fitted on the radiator inlet or the outlet? Or could it be either?
Also can you confirm that the inlet temp should be 12 degrees hotter than the outlet – that would seem to make sense to me!
Thanks
Hi Phil,
Thanks for getting in touch.
A TRV should always be fitted to the inlet on the radiator and the LSV to the outlet.
Also, you are about correct with your temperature calculations for the inlet and outlet too.
At Delta 50 the inlet temperature is 75 degrees Celsius and the outlet 65 degrees, which is more or less what you said above.
I hope this helps.
John
Thanks for the information John.
I’m not familiar with the term “Delta 50”, is this something I need to know?
“Balancing radiators is crucial for efficient heating distribution in homes. This article provides a clear and concise guide on how to achieve optimal balance, ensuring each room receives sufficient warmth. With step-by-step instructions, it empowers homeowners to enhance comfort while potentially saving on energy costs.”