Central Heating Problems & Solutions

finding a radiator leak

There are many common central heating problems and solutions, here we discuss them and how we can help you.

The inner functioning of a central heating system can be a mystery to most people and a complete puzzle when there is a malfunction. These central heating systems tend to malfunction, especially when you turn them on after a long period of disuse.

It is advisable to keep turning on the system on regular intervals when not in use to ensure that it is working correctly and the boiler is not loosing pressure – we advise against using leak sealant on heating systems However, if a problem arises with your system, you should not worry too much about it. Some issues are not complex so you can try and fix them yourself – a leaking radiator may be one of the more obvious leaks.. On the other side, a complex malfunction will need an expert’s intervention.

Either way, it will be a good idea if you are aware of the common problems associated with central heating systems. This way, you will have a good knowledge of the problem at hand when a professional comes in.

Components of a central heating system

Before we examine the common problems of a central heating system, let’s first discuss the various components of the system. Having a more in-depth knowledge of your central heating system will enable you to have a clear picture of the different malfunctions your system may have.

  1. Boiler

This is the main component of a central heating system and one of the most crucial parts of the entire heating system. It runs on several diverse sources. Your boiler is maybe running on either electricity or gas. The main types of energy sources boilers run on include natural gas, LPG, electric and biomass fuel.

Some boilers also run on a combination of sources; for example, a particular boiler may run on both gas and electricity. Other boilers may run on both natural gas and LPG energy sources.

Before attempting to repair your central heating system, it is advisable that you are sure of which kind of energy your boiler runs on.

  1. Radiators 

The radiators function is to transfer warmer air into the house while it pushes the colder air back to warm it and then transfer it to the air. Most radiators are built of steel, but you can find an aluminium or copper radiator.

  1. Pipes

Pipes allow hot water to flow into other parts of the heating system like the radiators. They are mainly made of either copper or plastic, 8mm or 55mm in diameter.

  1. Expansion vessel

This is another essential component of the central heating system. It is responsible for allowing the pipes to expand when the water is heated. When water is heated, pipes tend to expand and so to stop the pipes from bursting the expansion vessel is installed to help in expanding the pipes

  1. Pump

This component is sometimes found inside the boiler or sometimes in the airing cupboard. Its function is to push the heat around the system.

  1. Room thermostat 

This component measures the overall temperature of a room. When the temperature is too cold, it will signal the central system to turn on while if the temperature of a room is too high, it will signal the system to turn off. This component requires a free flow of air so it should never be blocked by anything like curtains, and it is not supposed to be put near heat.

Types of boilers

There are four main types of boilers that central heating systems can use. These are combination boilers, conventional boilers, system boilers and condensing boilers.

  • Combination boilers

The combination boiler commonly referred to as the combi boiler is very efficient and compact. These boilers heat water from the mains so that you do not need any hot water storage. They function as water heaters and also as central heating systems in one unit.

As a result, combi boilers are very convenient for smaller homes. They are also energy efficient since you will not need to heat water and store it and later go to waste if not used.

  • Condensing boilers

These types of boilers are known to extract the heat from the gases given off in the air when fuel is burnt. The working of a condensing boiler subsequently makes it very cost-effective and also energy efficient.

They are effective because they extract 90% of the heat (that would have been lost in the atmosphere) produced and fuel is burnt. In respect to this advantage, every new boiler that is to be installed in the UK has to be condensing.

  • System boilers

This type of boiler heats the central heating system and also produces hot water. The system boiler needs a hot water storage cylinder where it can store the water it has heated. It however, does not require cold water storage, which makes them convenient for smaller homes since it saves on space.

  • Conventional boilers

This boiler is sometimes referred to as the heat only boiler or traditional boiler. The conventional boiler requires both a water storage tank and an also a cylinder since it is able to provide large volumes of hot water to several bathrooms within a home.

Due to this fact, the conventional boiler is not fit for smaller homes since it requires a larger space for storing its heated water.

With this detailed information of the central heating system, you can now easily understand the problems that are associated with the system. Subsequently, you will be able to discover the malfunction and whether it needs a professional to fix it or not.

The most common central heating problems and solutions

Listed below are some of the most common central heating system problems. Some problems are straightforward to fix, while others may need a professional’s intervention.

  1. No heating/water not hot

  • You will first have to check if the central heating programmer is on since it can be erroneously turned off. After you have confirmed that it is on, then you can proceed to check that the thermostats have been correctly turned up to the right level. If both are fine, you can go ahead and check whether the electricity supply has been switched on. If everything is okay, but the heating programmer is not receiving any power, then you will need to invite an electrician since the connection might be loose.
  • Check the pump, if it is running, but the boiler is not lighting, check whether the pilot light is on and also that the gas supply has been turned on at the meter. If you confirm that the pilot light is off, then you need to read the casing or the boilers handbook on how to light it. If you try to light the pilot light, but it won’t stay on, then the flame gadget might need renewing. You will need to look for the assistance of a central heating engineer.
  1. Boiler is noisy

  • If a boiler is making a lot of noise, it is a sign of a serious problem but before calling a central heating system engineer, here is something you can do. You could first check the thermostat, if it set too high, that means that the water in the boiler might be overheated, which causes the noise you are hearing. Unfortunately, turning the thermostat down may limit the radiators ability to reach the right temperature. You can try to turn off the system before calling in an engineer.
  • If the thermostat is not set too high, then it could be that some parts of the boiler have limescale. Check the parts that have the limescale and descale if the part is reachable, but if you cannot reach the part of the boiler, it is advisable that you contact an engineer.
  1. The radiator has cold patches at the bottom. 

  • When there are cold patches at the bottom of the radiator, it might be because of rust, sludge or scale build-up that is minimizing the water the flow of water To solve this, you need to remove the build-up. If your heating system is an open vented one, then you can clean up the build-up with a heating system build-up remover – a chemical that you add to clean up the sludge or rust.
  • However, if your system is not open vented, then you will need to remove the build-up using a hosepipe. Using a hosepipe to clean up, is the work of a professional so you will obviously need professional help.
  1. The radiator is cold at the top

  • If this happens, it only means that there is air and you need to bleed the radiator. This is done by letting the air out of the radiator. First, you will need to check whether there is still warm water and then turn off the system. You will also need to find the bleed valve which is found near the top on the side of the radiator. Find a towel or a bucket and place it under the valve and then turn the valve anticlockwise to 180 degrees using a bleed key. If you lost the bleed key, you can find it at a DIY store near you. The air will be let out, and water will start to drip. If this happens, close the valve. If this problem persists, you will need a central system engineer to help with the system.

Central Heating Advice


We are the real experts when it comes to central heating leak detection services in the UK. From inspecting that home radiator for leaks, to detecting that pool leak; we have you covered in every aspect..

Speak to our customer care team today on 0800 731 3843 for further information or any queries you may have.














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