Broken Heating

The heating season is upon us, and now is the time when we will all start putting our heating on daily. This can put a strain on the heating system, especially when it hasn’t been used for a long while. During this first spell of heating days and weeks, there are some common heating issues that you may come across.

Below, heating expert Matthew Jenkins at explains how you can identify the most common heating problems and provides advice on how to rectify each issue.


Radiator Cold at the Top

If your radiator is cold at the top, this is usually due to trapped air in the system. To allow the air to escape, you will need to bleed your radiators. Bleeding a radiator is quite a simple job. It only takes a few steps and doesn’t take long at all to complete.

It is recommended that you bleed your radiator system at the start of the heating season, as this will allow you to make sure your heating system is working properly and there is no trapped air present before you begin using it. You should aim to bleed your radiators at least once each year.

When bleeding a radiator, you will need an old rag to collect water that spits out of the radiator, and you will also need a radiator key.

Take the steps below to successfully bleed your radiator:


  • Run your hand over the radiator and check if it is cold at the top or the bottom. If the top of the radiator is cold, this means that there is air trapped inside and that the radiator needs to be bled.
  • Start by turning off your central heating system.
  • Then, place a rag or old piece of cloth underneath the valve so that you can catch any water that may start to drip out while you are bleeding the radiator.
  • Use your radiator key and turn it anti-clockwise by roughly a quarter of a turn. It should start to hiss. Leave it open until the air stops coming out and water starts running out of the valve.
  • As soon as water starts coming out of the valve, turn the radiator key to the off position again.
  • Bleed any other radiators that need to be bled while your central heating system is still off.
  • Check your boiler pressure.
  • You can then turn your central heating system back on, and the issue should now be resolved.


You should always bleed your radiators when the central heating system is turned off. You must also wait for the system to cool down before proceeding with the job. If you bleed your radiators while they’re still hot, this could result in burns or scalds.

If you are bleeding multiple radiators, start by bleeding the downstairs radiators first. Also, start with the radiator that is furthest away from the boiler.


Radiator Cold at the Bottom

There can be multiple reasons why a radiator could lack heat at the bottom. However, the most common reason for a radiator that is cold at the bottom is a build of debris and sludge. Due to radiators being a constant damp environment, we often see a build-up of debris which accumulated over the years. This is often an accumulation of dirt and rust. Over time, the dirt and rust can start to block or restrict the flow of hot water, causing parts of the radiator to not have the ability to heat. As a blockage is present, water is then redirected to different parts of the radiator, meaning the bottom may not get the flow of hot water.

Luckily, there are several DIY steps you can take in order to fix the problem before having to call out the professionals. One step you can take to remove the sludge from your radiator is to add a chemical cleaner to your radiator system. To do this, purchase a central heating system cleaner from your local hardware store and add the correct amount instructed on the bottle to your radiator system. Allow your heaters to run for roughly an hour before flushing out and replacing the water. Flushing the radiator out will involve removing it from the wall, so if you’re not comfortable doing this yourself, it’s always best to call a professional to carry out the task for you.

Usually, a chemical cleaner can get the job done in an hour or so. However, if you’re dealing with a large build-up of sludge, you may want to leave your chemical cleaner in your radiator for up to a week before flushing. This will give the chemical cleaner enough time to break down all the dirt and debris that has been collected over the previous years. You must always remember to flush the radiator and replace the water after completing a chemical clean so that you know your radiator is safe for use in your home.

If you’re against using chemical cleaners and would prefer to go down an eco-friendly, non-toxic route, you can opt to remove your radiator and clean it yourself. To prepare for cleaning the radiator, you should first isolate it by closing the lock shield valve. This will prevent any excess water from leaking out of it. Make sure the central heating system is turned off, and give the water inside enough time to fully cool down. This will prevent any chances of burning or scalding yourself with the water. To close the lock shield valve, you may need to use a spanner. If you have a thermostatic radiator valve (TRV), turn it all the way down to zero. If the radiator does not have this function, you’ll need to turn another valve on the opposite side with a spanner.

Next, you will need to empty out the water inside your radiator. You must prepare your surroundings in case of any spillages. Make sure your flooring is covered and have buckets set aside in case you need them. Use a bleed key to open up the valve at the top of the radiator. This will allow the air to move through the system, and the water will start to pour out of the loosened valves.

Once the water has stopped coming out of the valves, disconnect the radiator from the wall and pour the rest of the water out. Ensure you don’t fully undo the valves when you disconnect the radiator, as this could cause water to flow from your central heating system, which may result in flooding your home. Use a hose to give your radiator a quick blast. This should shake out and remove any remnants and debris from the interior pipes. Make sure the water runs clean, and then reattach your radiator to the wall. You will need to attach the fixtures and turn all of the valves back to their original positions. When the water starts to flow back into the system, close the bleed valve and give your central heating system a test run to assess whether everything is functioning sufficiently.

The last step you can take to fix a radiator that is cold at the bottom is power flushing. Power flushing is a process that should be left to the professionals, as it requires some specialist equipment. Power flushing your radiator is a great process if you’re trying to clean multiple radiators. Power flushing is basically the same process as cleaning just one radiator. However, the professional will push water and cleaning chemicals at a high pressure through your central heating system. This will allow them to clean out the entire heating system in one go. If more than one of your radiators is acting up, this may be the best option for you.


Strange Noises Coming From The Boiler

If your boiler is making strange noises such as banging, hissing, or popping sounds, this isn’t normal and will usually indicate that there is an issue with your heating system. In some cases, it could mean that your boiler is overheating, which can be a very serious hazard if not dealt with quickly.

Firstly, turn off your boiler and check if any of the sounds persist. If they do, the problem is not with your pilot light, but instead, the problem is likely due to trapped air. Find the bleed screw on your boiler and allow any trapped air to vent out of the system. You may also want to try descaling your boiler to see if that gets rid of the noises. However, you can’t descale all boiler systems by yourself, so you’ll need to check the manual to see if this is possible. If you’re unsure or the noises don’t stop, you will need to call a professional.

Hissing noises could sometimes be due to a lack of water supply to the expansion tank and the feed. If you have a combi boiler, you won’t have an expansion tank. However, other boiler types will usually have a tank. Most often, this is found in the loft. Check your system for any obstructions, such as a build-up of sludge. The problem may also be due to valve issues or a frozen pipe.

It’s important that you never ignore any unusual sounds that are coming from your boiler. The best course of action is to speak to a professional as soon as possible. Remember that boiler noises could be a sign of a serious or hazardous issue, so they should never be ignored.


No Heat or Hot Water

In some cases, you may find that your heating system is not producing any heat at all, including hot water. The first step you need to take if this happens is to check that the central heating system is switched on. Sometimes, you may find that a fuse has blown, causing the central heating to switch itself off. If the fuse and switches are all in order, but your central heating system isn’t coming on, you could have a loose wire somewhere. You will need to hire an electrician to fix this. 

If none of the above are the issue, check if your boiler’s pilot light is on. If the pilot light has gone out, you may need to relight it for the heat to work. In some cases, the issue may be your gas supply. Check if gas is coming through the system properly. If gas is the issue, call your gas supply company for an update and to find out how to fix the problem.

The no-heat issue could also be due to a problem with the pump. Try turning the pump off and on manually. Give it some time to cool down before you switch it back on. For most pumps, you will need to locate the screw in the centre of the pump and remove it. Then, turn the manual starter to restart it. Make sure you follow the instructions in your system’s user manual to make sure you’re doing it correctly.

Issues with boiler pressure can also cause some problems with the heat and hot water. If the pressure gauge on your boiler is showing high pressure, call a professional right away. If the pressure is low, you may need to add some additional water to the system until the pressure returns to normal. Always check the user manual for the right method on how to do this.


Problems With an Aging Boiler

With careful maintenance, a boiler can last for a very long time. However, most boilers have a lifespan of around 10 – 15 years. As your boiler ages, it will become less and less efficient and will be more prone to faults and breakdowns.

Sometimes, it’s much better to invest in a brand-new boiler before you come across any issues, as boiler problems could end up being expensive if you have to deal with them last minute. You don’t want to be left without heat or hot water during the winter months.

Regardless of how old your boiler is, it’s important that you get it serviced at least once each year. This will ensure that any minor faults are identified quickly and dealt with before they become a much bigger issue.