For a large number of people, the inner workings of their boiler and central heating system remain a mystery. Boilers and central heating are not free from faults and malfunctions. This makes it a frustrating situation to deal with when something goes wrong. Particularly during the cold winter season when you need heat the most.

According to service providers, they usually receive the most complaints about central heating problems in autumn. This is usually because most homes turn off their boiler and central heating in the summer. After being idle for several long months, your central heating may not function perfectly. This is why it is usually good practice to switch on your heating system during the summer at regular intervals.

However, despite your best efforts, your central heating system could develop some problems. This is nothing to worry about. Breakdowns and malfunctions come with the nature of a system that works continuously during the cold seasons. So do not worry if your heating system develops a fault.

In many cases, problems with your central heating can have a straightforward solution. You can even fix some minor faults and issues yourself. However, do not panic if something beyond your understanding happens to your heating. You can always have a professional heating engineer or plumber come and look at it. Most of the time, it is a good idea to let the professionals do their job. DIY repair jobs can often have disastrous results. However, if you are confident in your ability, read on for some common central heating problems and their solutions.

Common Central Heating Problems & How to Fix Them

It is almost time to start switching on your heating systems as autumn approaches. This helps you figure out if your heating system is working properly. Finding any potential problems in autumn and having them repaired is much better than a breakdown in winter. Imagine being stuck without heating in your home when you need it the most!

The earlier you switch on your heating system, the earlier you can identify faults. Since your heating has likely been off for several months, there is a good chance you might face some problems. These may include the most commonly occurring ones listed below. 

#1. Cold Patches on Radiators

You may find out that your radiators have cold patches on them. This is a problem you can likely fix yourself, but first, you need to know where the cold patches are. Cold patches on your radiators can be due to different reasons and have different fixes.

Cold on Top: If your radiator is only warm at the bottom and cold on top, you have a problem. The cause behind this is likely to be air trapped in the system. To let the air escape, you need to bleed your radiator out. First, you should switch off your heating system. Next, place a bowl beneath the radiator to catch spillage and locate the bleed valve. Your radiator should come with a bleed key that lets you open this valve. Open it just enough until you hear air escaping. Once the water starts dripping out, close the valve. Switch on the system and make sure you check and adjust boiler pressure. This should solve the problem.

Cold at the Bottom: A radiator that is cold at the bottom usually have something obstructing the flow of water. In most cases, this can be rust or scale. In extreme cases, it can be a sludge build-up. If you have an open-vented system, you can fix this yourself. Simply add sludge remover to the system, which will clear away the obstruction. However, if you do not have an open-vented system, you will need to call a professional. These systems require someone to flush the pipes, which can be tricky to do yourself. 

Cold in the Middle: Sometimes your radiator is cold not at the top or bottom, but in the middle. This is again likely due to an obstruction of sludge or rust. However, this can be more difficult to fix than if the radiator is just cold at the bottom. You will need the services of a professional plumber to fix this problem.

#2. Hot and Cold Radiators

Sometimes you have hot and cold radiators on different floors. This is likely an indication of something obstructing the flow of water in the system. You need to check which radiators are hot and which are cold. Make sure the cold ones have their valves open, or if needed, open them further.

If the cold radiators are upstairs, the problem may be because of low boiler pressure. You may need to introduce more water into the system to return to normal pressure. If the cold radiators are downstairs, the culprit could be a malfunctioning pump. This is not something most people can fix on their own. You may also need to descale your central heating system. This is quite similar to removing sludge from the system, but it is best if you leave it to a professional.

#3. Boiler Making Strange Sounds

If your boiler is making popping, banging or hissing sounds, you should be wary. These noises often referred to as “kettling”, are not normal and usually indicate a problem with your boiler. It could even mean your boiler is overheating, which can be a serious hazard.

Turn off your boiler and check if the kettling sounds persist. If they do, the problem is not with your pilot light but with trapped air. You will need to find the air bleed screw on your boiler and vent any excess air from the system. You could also try descaling your boiler to see if that fixes the noises. Otherwise, you will most likely need help from a professional. Remember, you cannot descale all boiler system types by yourself, so be sure to double-check your user manual.

Sometimes, hissing noises are the result of insufficient water supply to the feed and expansion tank. If you have a combi boiler, you will not have an expansion tank. However, regular and system boilers usually have a tank located in the loft. Check to see if there are any obstructions in the system, such as a sludge build-up. There could also be a problem with a valve or a frozen water supply pipe.

You should never ignore strange and disturbing noises coming from your boiler. It is best to reach out to a professional as soon as possible when experiencing such problems. You do not want a safety hazard on your hands.

#4. No Hot Water or Heat

Sometimes, your central heating system can encounter a problem where it is not producing any heat at all. There are a few simple solutions to try before you call a professional for help. First, check if your central heating system is switched on. In some cases, a fuse might have blown which means your central heating will not work until you replace it. If the switches and fuse are in order, you could have a loose wire. This will require an electrician to fix.

If none of the above are the problem, check your boiler to see if the pilot light is on. If it has gone out, you may need to relight it before you can get heat. Sometimes, the problem could be your gas supply. Check if the gas supply is coming through to your system properly. If not, call your gas supply company and ask them to fix the problem.

The problem could also be because of a malfunctioning pump. Try turning it off and on manually. Switch it off, wait for it to cool down and then restart it. To restart most pumps, you need to locate and remove the screw in the middle of the pump. Then you turn the manual starter to restart it. Follow your user manual to do this properly. However, if this does not work, you may need a professional to flush the pump clean.

Problems with boiler pressure can cause problems with hot water and heat. If your boiler’s pressure gauge shows you that the pressure is too high, call a professional immediately. If the pressure is too low, you may need to add water to the system until it rises to normal again. Check your user manual before you do this.

Frozen condensate pipes can interfere with your central heating system and cause loss of hot water and heat. Most modern boilers are condensing boilers and come with a condensate pipe that can freeze in cold weather. You will need to thaw out the frozen pipe using hot (but not boiling) water. To avoid frozen condensate pipes, it is usually a good idea to insulate them.

Sometimes, the problem could lie with your motorized valve. Check it to see if it is the culprit. Using the manual lever, try to open the valve. If there is resistance, calling an engineer to fix the problem is your best option.

#5. No Hot Water but Central Heating Works

In some cases, you may encounter a problem with your central heating system where your central heating works but you have no hot water. This can be because of several reasons. Your thermostat may be set to low. You can easily check this on the programmer and set the thermostat to at least 60°C. Sometimes, your motorized valve could be the problem if it is not open. If you have a motorized valve fitted to your cylinder, check if it is open. The problem could also be because of air trapped in your hot water cylinder if your system has one. This is easy to fix. You simply have to bleed out the excess air from the air-release valve. You can usually find it on the pipe entering the heating coil. 

#6. Leakages

Leaking pipes are a fairly common problem with central heating that can be a nuisance. If you have a leaky pipe joint, you can likely tighten it yourself and hopefully fix the problem. Be careful not to damage the pipe or the joint. A quarter turn at a time while tightening is the best way to do this. In case tightening the joint does not help, you may need to apply some sealant. However, this is just a temporary solution, meaning you will need no replace the leaky pipe as soon as possible. You can continue to use sealant as a temporary fix, not a permanent one.

#7. Non-Stop Overflows

If you own a combi boiler, you will not have this problem because you will not need a water tank. However, system and regular boilers get their water feed from a tank usually found in your loft. These water tanks come with a ball-cock to regulate the flow of water and prevent overflows. However, sometimes the ball-cock can get jammed, causing the overflow to run non-stop. Try to un-jam the ball-cock to fix the overflow problem. However, you should only let professional plumbers handle immersion tanks.

#8. Ageing Boiler

Most boilers have a useful life between 10 to 15 years. With careful maintenance, your boiler can last for a long time. However, as boiler ages, it becomes less efficient and more prone to breakdowns and faults. Sometimes, it is better to replace your aging boiler replaced than to continue to spend money on repairing it. Regardless of the age of your boiler, you should get it professionally serviced at least once a year. This helps to make sure any small faults can be dealt with before they turn into expensive problems. You may also want to consider getting a boiler and central heating system cover to help protect you against expensive repair jobs.