Please note this article is designed as a general guide for consumer awareness only. A fully qualified heating engineer will adopt a different and far more technical approach which looks at many other factors to ensure your system is optimally set. Viessmann always recommends you speak to a heating engineer in this instance.
We often take our radiators for granted — they heat up and cool down automatically depending on the programme of your heating system. However, if you find cold spots or discover that one radiator isn’t getting warm at all, you’ll certainly notice the temperature difference in your home.
In some cases, your radiators may need bleeding. This process involves taking air out of the system that could be blocking the hot water from heating a radiator fully. However, if you’ve tried this and you’re still finding issues with one or multiple radiators heating up, it could be that they need balancing instead or that the system might need flushing by a qualified engineer.
Shrnutí témat:
- What does balancing radiators mean?
- When to balance radiators
- How often should you balance your radiators?
- Do I need to balance or bleed my radiators?
- How to balance a radiator
What does balancing radiators mean?
When you balance a radiator, you’re adjusting the flow of water in the system. If you have one radiator that is always colder than the others, balancing will allow less hot water into the hottest radiators and more water into the cooler one to make sure it reaches the right temperature. Bleeding, on the other hand, is about removing air from the system.
When to balance radiators
Put simply, if you notice that some radiators in your property are warmer than others — despite being on the same setting — or if these radiators don’t heat up at the same speed as each other, it’s likely time to balance your central heating system. Cold spots and uneven heating output happens when the hot water produced by your boiler is not distributed evenly. Luckily, if this is indeed the problem, balancing your radiators is a relatively quick and easy process.
How often should you balance your radiators?
Unless your central heating system has had work done on it — such as a system flushing/cleansing or a boiler/radiator replacement — balancing can be done on a periodical basis. This is to say, you only really need to bleed and potentially balance your radiators if your radiators are heating up at different speeds. However, you will always need to ensure your radiators are balanced after work is done on your central heating system.
Do I need to balance or bleed my radiators?
Although connected, balancing and bleeding radiators are different processes. You may find that you need to do both of these things in order to get your radiators working properly again.
As discussed above, bleeding a radiator involves removing any trapped air from your central heating system that may be blocking hot water from heating a radiator. If you are experiencing cold patches in certain radiators, or some radiators performing more effectively than others, bleeding should be your first thought. Here’s our video guide on how to bleed a radiator.
If, however, bleeding your radiators does not solve the issue of certain radiators heating up more efficiently than others, you will likely have to balance the system instead. We explain how this can be done below.
How to balance a radiator
Below, you can find all the steps you need to successfully balance your heating system. Before following these instructions, you should allow the radiators to cool down completely and bleed them using a radiator bleeding key.
Is there a tool for balancing radiators?
Although there are not any unique tools required for balancing radiators, there are a number of common tools needed to make this job possible. These can all be found in a typical toolbox and, if you don’t already own them, can be bought relatively inexpensively from any DIY shop.
These tool include:
- Standard radiator bleeding key
- Screwdrivers (both Phillips and flathead)
- Lockshield valves key (or an adjustable spanner)
Important: Please note that this work is usually done by an engineer as water leaks can occur when adjusting radiator valves.
Krok 1: Locate the lockshield valve on each of your radiators. These will normally be located on the opposite side to the thermostatic radiator valves (TRVs) that are used to control the heat output. Remove the lockshield valve caps from all radiators.
Krok 2: Now that the valve caps have been removed, you should be able to open and close the valve to each radiator. Open the valves by turning them to the left. Repeat this for all of your radiators.
Krok 3: Once every valve is open, turn your heating on. You need to monitor which radiators heat up fastest. It may be easier to have a family member or friend to help you with this task, otherwise you’ll be running around the house trying to determine what each radiator is doing. Radiators nearest the boiler will probably get warm first, so take this into account.
Krok 4: Turn the heating off again and wait for everything to cool down. You should now have a list of which radiators are getting hottest the fastest and those that maybe aren’t getting hot at all or have cold spots. You’re doing this to balance the flow of water running through the system. Turn the heating back on.
Krok 5: Go to the radiator that heated up the fastest and close the valve that you opened in Step 2 by turning clockwise. Once it’s fully shut, open it slightly using your lockshield valve key. Now repeat and move to each radiator, the furthest away radiators may need to be opened more than those closest to the boiler.
If you’ve followed all of these steps, what you have done is restricted the hot water flow to radiators that are the warmest and allowed more water into those that need it more. Your radiators should all be balanced and you can enjoy your warm home.
How long does it take to balance radiators
Unlike the bleeding process, which typically only takes a few minutes to complete, balancing radiators can take a couple of hours to complete from start to finish. That being said, some of this time will be spent simply waiting for your radiators to heat up and cool down.
Does balancing radiators save money?
Balancing your radiators can save you money on your heating bills. This is because you’re giving the correct balance to each radiator to ensure your boiler doesn’t keep cycling on and off and giving your system a nice smooth flow. If you are looking to save even more money on your heating, try turning your thermostat down by one degree.
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Many people aren’t aware of the impact that a poorly balanced system can have, chiefly that it can drive up your bills during the colder months.
The same goes for radiators that need bleeding. They don’t heat up fully so you have to leave your radiators on for longer, driving your heating bills up.
Read on to find out the best why to diagnose unbalanced heating systems and how to balance and bleed your radiators.
Thinking about your heating costs this winter? Head to our tips for reducing your heating bills
How to balance your radiator
Why do I need to balance my heating system?
In an unbalanced system the temperature your home reaches may not match the one you set. For example, when you set the thermostat to 20°C you would expect the whole home to heat to, and stay at, 20ºC.
However, with an unbalanced system, the upstairs might actually reach 23°C, while the downstairs remains relatively cool at 17°C. You may then be tempted to turn up the thermostat (in this example to 23°C), which will create a comfortable temperature of 20°C downstairs, but superheat the upstairs to 26°C.
The Energy Saving Trust estimates that turning up the thermostat by just one degree costs an additional £75 a year in heating costs. So turning up the thermostat will just increase your bills, whereas getting your radiator rebalanced will save you money in the long run.
How do I know if my heating system is unbalanced?
The telltale signs of a poorly balanced system include some radiators heating up much faster, or getting much hotter, than others in your home.
Another clear sign is if certain parts of your house (such as upstairs) get uncomfortably hot, while other parts stay cool.
Why is my system unbalanced?
Your system can become unbalanced for a wide variety of reasons:
- Sludge and debris Old systems may be clogged up, causing blockages in some radiators, meaning they take longer to heat up.
- Vymalování When radiators are removed and replaced, perhaps during decorating, this can impact the balance of the heating system.
- Misuse of Thermostatic Radiator Valves (TRVs) If TRVs have been fitted to radiators around your home, and not adjusted correctly, this can lead to system-balancing issues.
It’s easy to tell if you have inadvertently unbalanced your own heating system with TRVs:
- Turn all radiator thermostats to 0.
- Turn the central heating off and wait for at least two hours for the system to completely cool off.
- Starting from the radiator furthest from the heating source if you have a combi boiler, or furthest from the water pump (usually found in the airing cupboard next to the hot water cylinder) if you have a heat-only boiler, turn all thermostats to 2.
- Starting from the radiator furthest from the heating source, check if all radiators get hot evenly across the radiators at the same rate.
If they don’t, the system is not balanced properly and we would recommend that you call a Which? Trusted trader to assist with what will be a much more technical method of balancing your heating system.
How a heating engineer will balance your system
- Turn off the boiler for at least two hours for the system to cool off.
- Turn on the boiler from cold.
- Measure whether there is a flow differential (DeltaT) of at least 20°C at the boiler.
- Measure whether the return temperature is below 55°C (this is essential for condensing to occur, and for your boiler to be operating at its advertised efficiency).
If the flow differential is less than 20°C, or the return temperature is higher than 55°C, then the system is either unbalanced or the radiators are too small. Either way, you will need a heating engineer to fix it.
A heating engineer will first completely drain the system and remove any air pockets by bleeding the radiators. They will then refill the system with all of the radiator valves fully open. The next step will be to adjust the valves on the radiators that get hottest the fastest. This it to restrict the flow of water to the radiator and even out the spread of heat to the rest of your home.
Costs for this will vary between £100 and £200, but expect the heating engineer to take at least half a day to complete the work.
If you’re ready to call in a heating engineer to balance your radiator, you can use our Which? Trusted Traders search tool to find an accredited trader near you. All of our traders have been vetted so you can trust them to do a great job.
If you decide it’s time for a new boiler, make sure you buy from the best gas and oil boiler brands
Jak odvzdušnit radiátory
Jak poznám, že moje radiátory potřebují odvzdušnění?
Radiators need bleeding every few years to get rid of trapped air bubbles. The air bubbles rise to the top of a radiator so place your hand on the top each radiator while the heating is on. If the top of the radiator is cool, or much colder than the bottom of the radiator, it’s a sign your radiators need bleeding.
Instructions on how to bleed your radiator
Bleeding a radiator is a task you can carry out yourself. All you need is your radiator bleed key, and a spare cloth or towel and container to catch any water that could potentially leave your radiator when you start bleeding it.
- Turn the heating off Let the radiator cool down for 20-30 minutes so you don’t risk burning yourself with hot water.
- Locate the radiators bleed valve Usually located on the side of the radiator, at its top. If you’re bleeding multiple radiators, start with the one on the ground floor furthest from your boiler.
- Place a container under the valve This is to catch any water that may drip out of the valve. Also hold the spare cloth or towel under the valve.
- Insert the radiator bleed key and open the valve Open the valve slowly, turning anticlockwise, until you hear a hissing sound. This is the trapped air escaping. Only open the valve a maximum of half-a-turn, so any water doesn’t escape too quickly.
- Close the valve when water starts leaking out At this point all the trapped air has been removed so turn the key clockwise to close it. Repeat for all the radiators you need to bleed.
- Check your boiler’s pressure After bleeding several radiators, it is normal for the heating systems pressure to drop. Check the boilers pressure indicator, it should be between 1.0 and 2.0 bar (often highlighted green). You can increase the boiler pressure if needed, follow the manufacturer’s instructions to do this. If you’re unsure contact your boiler manufacturer’s technical department or a qualified heating engineer.
- Turn the heating on Give your radiators time to heat up and check the cold areas at the top of the bled radiators have gone.
Read our guide on getting the best boiler service to get your boiler running as efficiently as possible
