How to balance a radiator - a complete guide

How to balance a radiator - a complete guide

Properly functioning radiators are crucial to maintaining a comfortable temperature in your home during the colder months of the year. However, if your radiators are not balanced correctly, you may experience uneven heating throughout your home. This can result in wasted energy and higher heating bills. Balancing a radiator involves adjusting the flow of hot water through the radiator to ensure that each room in your home is heated evenly.

In this article, we will explore the process of balancing a radiator step-by-step, from identifying which radiators need to be balanced to making the necessary adjustments. We will also discuss the tools and equipment you will need to complete the task and provide some tips and tricks to make the process as simple and straightforward as possible.

Why do I need to balance my radiators?

A central heating system may need balancing for several reasons.

One of the most common reasons is that the system may not be distributing hot water evenly throughout your home. This can be due to a variety of factors, including the size of your property, the layout of your home, the position of your radiators and if you've had additional radiators added to your system.

If some rooms in your home are warmer than others, this could be an indication that your central heating system is not balanced correctly. When a heating system is unbalanced, it can result in hot and cold spots throughout your home, which can be both uncomfortable and inefficient.

Heating expert, Nicholas Auckland, has this to say on the matter:

"Balancing your central heating system involves adjusting the flow of hot water through your radiators to ensure that each room in your home is heated evenly. This can be done by adjusting the valves on your radiators, which control the flow of water. By balancing your central heating system, you can increase the flow of hot water to the colder areas of your home and decrease the flow of hot water to the warmer areas, resulting in a more even distribution of heat throughout your home.

A balanced central heating system can not only make your home more comfortable, but it can also save you money on your heating bills. An unbalanced system can cause your boiler to work harder than necessary, resulting in higher energy usage and higher bills. By balancing your radiators, you can ensure that your heating system is working efficiently and effectively, keeping you and your home warm and comfortable without breaking the bank."

A heating engineer adjusting the temperature of a radiatorA heating engineer adjusting the temperature of a radiator

How to balance radiators - step by step

Tools you'll need

  • Adjustable spanner or pliers
  • Flathead screwdriver
  • Radiator bleed key
  • Old cloth or towel
  • Radiator balancing kit (optional)

Step 1 - Turn off your central heating

Before you do anything, make sure that your heating system is turned off and you give your radiators a chance to cool down. Scalding yourself due to hot rads is not a good way to start so take this step seriously.

Step 2 - Bleed your radiators

If you identified any radiators that were only getting hot at the bottom, then this would be a great time to bleed any air out of your radiators and get this issue resolved.

Step 3 - Go to radiator number 1

This will normally be the radiator that gets hottest the quickest. It's often the closest to the boiler and will quite often be upstairs, if you're in a two-storey home. This is likely to be the radiator that is responsible for pinching all the hot water and sending it back to the boiler rather than to the rest of the radiators.

Step 4 - Close then open the lockshield valve

On radiator number 1, go to the lockshield valve. This is the valve that usually has a pointed plastic cover on it and looks like it doesn't do much.

Take a flat head screwdriver (or a pair of grips) and fully close the valve by turning it clockwise as far as it will go. Then open the lockshield valve (anti-clockwise) by a quarter or half turn.

Step 5 - Open thermostatic radiator valves (if applicable)

If you have thermostatic radiator valves (TRVs) on your radiator, then it's important to ensure they are fully opened when going through the balancing process. You can fully open TRVs by turning them anti-clockwise until you can't turn any further. Once you've switched your heating back on (step 6) and established that your system is balanced, then you can go back and set your TRV to your desired setting.

We have TRVs available under our radiator valves section. You can browse the full range here.

Step 6 - Switch on your heating system

You might find that just closing and opening the lockshield valve on radiator number 1 is enough to solve the problem and get all your radiators heating up equally. After dealing with the first radiator, you could switch your central heating system on and find out.

Step 7 - Repeat process if necessary

If the problem doesn't appear to be solved, turn the heating off again. Repeat the process described in Step 4 on all radiators and then turn your heating back on. You should find that this has solved the problem and all radiators are getting up to temperature exactly as they should be. If not, them it's time to call in a professional.

How to balance a vertical radiator - step by step

The main difference between a vertical radiator and a horizontal radiator (apart from the obvious orientation) is the fact that many vertical radiators contain something called an 'internal diverter.' An internal diverter is a component designed to control and direct the flow of hot water upwards (against gravity) through the vertical radiator to maximise its efficiency. This internal diverter is located inside the radiator and serves several important functions:

  1. Efficient heat distribution
  2. Prevention of cold spots
  3. Increased heating efficiency
  4. Energy savings

If the internal inverter in a vertical radiator becomes faulty, it may produce very similar symptoms to a radiator that needs balancing. The radiator is unlikely to get very hot or it might feel warm at the bottom but cold at the top. If the radiator has a tubular design, then the last one or two tubes might not get hot.

The best way to identify if it's a balancing or diverter problem is to go through the process of balancing the vertical radiator (described below) to see if that resolves the issue. If not, then it's best to call in a professional plumber to look at the radiator in more detail.

Tools you'll need

  • Adjustable spanner or pliers
  • Flathead screwdriver
  • Radiator bleed key
  • Old cloth or towel
  • Radiator balancing kit (optional)

Step 1 - Establish your flow & return pipes

The flow pipe is where the hot water flows into the radiator, while the return pipe is where the water leaves the radiator to return back to the boiler. It's always useful to know which is which. If you're working on an existing radiator, run the heating and see which pipe gets hot first. This will identify it as your flow pipe. If you're installing a brand new radiator, the flow and return will usually be indicated with sticks on the base of your radiator. Alternatively, the manufacturer's instructions provided with the radiator will make it clear.

Step 2 - Locate the flow flap

Just inside the radiator entrance on the flow side is a small flap. This flap needs to be pushed down so that it diverts the water and pushes it up into the vertical radiator. If the flap is in the up position then it won't enable water to flow evenly throughout the radiator and will result in many parts of the radiator staying cold. If you are installing a new vertical radiator, this should be done before you connect the radiator valve. If a newly-installed vertcial radiator is not getting hot, it may be that the flap wasn't pushed down during installation. In this case the radiator will need to be drained, the valve removed and the flap pushed down.

Step 3 - Switch on your heating

Switch your heating system on to get water flowing into the radiator. This will establish whether you have solved the problem or if you need to balance the flow of the water coming into the water, as described earlier in this article and which will be repeated below.

Step 4 - Turn off your heating system

Because you will have just turned on your heating to check how the radiator is performing, you'll need to turn your heating off again and allow the radiator to cool down. Take this step seriously as it's very easy to scald yourself on a hot radiator when trying to rush to get the job done.

Step 5 - Bleed your radiator

There may be air in your radiator that is contributing to it not heating up properly, so take your radiator bleed key and go through the process of bleeding your radiator.

Step 6 - Fully close then partly open the lockshield valve

The lockshield valve will be located at one end of the radiator. It's usually the smaller of the two valves and doesn't look like it does much. Take your adjustable spanner, pliers or flathead screwdriver and fully close the valve by turning it clockwise as far as it will go. Then open the lockshield valve by a quarter or half turn in an anti-clockwise direction.

Step 7 - Fully open the thermostatic valve (if applicable)

If you have a thermostatic radiator valve (TRV) on your radiator, then it's important to ensure it is fully opened when going through the balancing process. You can fully open the TRV by turning it anti-clockwise until you can't turn any further. Once you've switched your heating back on (Step 8) and established that your system is balanced, then you an go back and set your TRV to your desired setting.

Step 8 - Switch on your heating

Putting your heating back on with allow water to flow into the vertical radiator and you'll discover if it now heats up evenly across the entire radiator.

Step 9 - Repeat if necessary

You might discover that other radiators in your home are not heating up correctly. If this is the case then go to each radiator and repeat the same balancing process as described above. If the problem is still not resolved and your vertical radiator, or others radiators, are still not getting hot, then it's time to call a professional.

How to balance a heating system

As well as making sure that hot water is flowing smoothly around your entire central heating system, it's also important that each of the rooms in your home are being heated up evenly and efficiently. There are some things to keep in mind that will make this process much easier.

1. Have the right-sized radiator

According to radiator specialist. James Auckland, it's fairly common in older properties, or properties that have had an extension built, that the installed radiators are actually too small for the room.

"If this is the case, then your radiator may well be on full blast but will still struggle to emit enough heat to comfortably warm up the surrounding area. This is an inefficient use of energy as the householder may try to turn up the temperature of their heating to compensate, or in the case of thermostatic radiator valves, the room may never get hot enough for the valves to stop the flow of hot water into the rad.

If you think your radiator is too small for the room it's situated in, then the best thing to do is to put the dimensions of your room into a heating calculator. The calculator will take into account all the aspects of your room and will give you a BTU heat output figure that you can use to choose a new, correctly-sized radiator."

2. Bleed your radiators

If your radiators have trapped air inside, they will not heat up properly. Bleeding your radiators will release any trapped air, which will allow hot water to circulate freely and heat your room evenly.

3. Use radiator reflectors

Radiator reflectors are panels that can be attached to the wall behind your radiator. They reflect heat back into the room, which can increase the efficiency of your heating system and reduce energy waste.

4. Position your furniture carefully

Make sure that your furniture is not blocking the flow of hot air from your radiators. If your sofa or curtains are blocking the heat, this can result in uneven heating.

A white vertical designer radiatorA white vertical designer radiator

How to balance a radiator with a thermometer

A radiator thermometer is a handheld device used to measure the temperature of a radiator's surface. It works by using infrared technology to detect the temperature of an object without making physical contact. These thermometers are valuable tools for balancing radiators and ensuring even heat distribution within a heating system.

To balance a radiator using a thermometer, please follow the steps below.

Step 1 - Run your central heating

Turning on your central heating system and allow it to run for a sufficient period to reach full operating temperature with water flowing throughout the radiators and pipework

Step 2 - Measure the radiator temperature

Point the infrared thermometer at various points along the surface of each radiator in your home and record the temperature readings from different sections of the radiator. IdIdeally, you want the radiator to have a consistent temperature from top to bottom. 

You should also measure the temperature at the point where the pipework intersects with the lockshield valve, either at the floor or wall. Then, take the temperature of the pipework connected to the manual valve or thermostatic radiator valve (TRV). 

Step 3 - Adjust the lockshield valve

If the top of the radiator is hotter than the bottom, partially close the lockshield valve to reduce the flow of hot water to the top. If the bottom of the radiator is hotter than the top, partially open the lockshield valve to allow more hot water to flow to the bottom. Gradually adjust the lockshield valve, paying close attention to the temperature reading, until you achieve an approximate 12°C variance compared to the initial lockshield valve reading you obtained in the previous step. It's important to be patient when carrying out this process as it takes time for the temperature to adjust each time to tweak the lockshield valves.

Step 4 - Repeat if necessary

You can repeat this process with your thermometer across all radiators in your home. Using a radiator thermometer adds a scientific dimension to the balancing process and allows you to get the exact temperature you need to ensure maximum energy efficiency.

Why is a 12°C temperature difference good for a balanced radiator?

The ideal temperature differential of around 12°C for a balanced radiator is a common rule of thumb. In simple terms, it means that the water going into the radiator should be 12°C hotter than the water going out of the radiator. It generally indicates that the top and bottom sections of the radiator are receiving a roughly equal amount of hot water and this 12°C difference has been deemed the most energy efficient way of running your boiler and heating system.

Don't get too hung up on getting a precisely 12°C difference, around this amount will be fine. The most important thing is that your radiators are heating up evenly.

Can I balance a radiator without a thermometer?

Yes, you can certainly balance a radiator without a thermometer. The step by step guide above, under the heading How to balance a radiator - step by step, explains exactly how you can do this.

While using a thermometer will give a very exact temperature reading, it's usually only professional plumbers and heating engineers that will have such a device. You can measure the temperature by touch to get a result that is good enough.

How much does it cost to balance a radiator?

If calling out a professional heating engineer, the cost for this service typically falls within the range of £100 to £200, and you should anticipate the heating engineer dedicating at least half a day to complete the necessary work.

To begin the process, the heating engineer will initiate a thorough system drainage and bleeding process, ensuring that all radiators are free of trapped air. The system will then be refilled with all radiator valves opened. Subsequently, the engineer will focus on tweaking the radiators that heat up most rapidly. This adjustment is designed to moderate water flow, promoting a more balanced heat distribution throughout your home.

If you wanted to balance your radiators yourself, following the instructions in this guide could safe you a considerable amount of money on professional services.

We pride ourselves on keeping a wide range of radiators, electric radiators, accessories, radiator valves and more. Browse our catalogue today.

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