Why Are My Radiators Not Getting Hot?

Having reliable radiators in your home that work whenever they are needed is a necessity. When the temperature drops outside, your home should be able to maintain a comfortable one inside. This is the main function of a radiator, so what happens when they are not heating up properly? Rather than having to replace your radiators entirely, there could be a simpler explanation and solution instead. If you have ever wondered why your radiators are not getting hot, here are some of the main causes and how to resolve them.

What are the Causes of a Lack of Heating?

Some of the issues that can cause your heating to struggle can be identified and resolved quickly, but some may indicate a larger problem. Here are some of the main culprits of why your metal radiators are not getting hot (apart from forgetting to turn them on!).

Air Pockets – Air can become trapped within your radiators, and this will impact how well they heat up. When air enters the central heating system, it will find somewhere to settle, usually at the top of your radiators. If you have touched your radiators when they are on and noticed that they are cold in places at the top but hot towards the bottom, this indicates trapped pockets of air. Quite simply, where the air has collected, it prevents the hot water from the system from filling the entire radiator. This is one of the most common causes of cold radiators that can be easily resolved (see below).

Sludge/Debris – Similar to air build-up, over time your central heating system will experience corrosion that will cause sludge or debris to accumulate. This will fall collect at the bottom of a radiator, taking up space where hot water should be. A common symptom of this happening is noticing cold areas near the bottom of your radiator whilst the top is hot. The debris stops the radiators from functioning fully, meaning your room will take longer to heat up. Just like with air, steps can be taken to remove this sludge.

Leaks – if there is a leak anywhere in the system, this will massively impact your radiators’ performance. This can cause air to enter the system that will block the radiators, as mentioned above, or water to leak out, meaning lower water pressure and poor performance. Leaks can happen over time from corrosion of the pipes if your system is not well-maintained. Depending on where the leak is located and how bad it has got, it can mean having to replace the pipes or even the radiator itself. Sometimes, it can just be as simple as a loose valve or nut that needs tightening.

Fault with the Thermostat – if the system is working fine and there are no other apparent issues, it could mean a problem with the radiator’s thermostat. Hopefully, it could just be the setting is too low and so would just need turning up, but in some cases, the thermostat valve may be the issue. If the valve seizes, it will be difficult to turn. Removing the valve cover can identify the issue, but the thermostat valve may need replacing entirely if not a quick fix.

Valve fault – If you have more than one radiator struggling to heat properly and the system is definitely turned on and the thermostat is up, it could be a valve issue. The diverter valve controls the flow of water to your radiators and taps. If you discover that your hot water is running normally from the taps, just not properly to your radiators, this could be the fault and would need the diverter valve checked and possibly replaced.


How to Fix a Cold Radiator – Common Solutions

Now that you know the reasons why your double panel or single panel radiators are not getting hot, how can you resolve this? Fortunately, many are quick fixes that you can try below, but others may require assistance.

Bleed your radiators

Your first point of call when looking at how to fix a cold radiator is to bleed them. This is the most effective way to remove any pockets of trapped air within the radiators. This shouldn’t need doing regularly, usually only 2-3 times a year ideally to keep your radiators working as they should. You’ll need your radiator valve key and a cloth before you begin, and to ensure the heating is turned off and your radiators are cooled down.

Inserting the key into the valve at the end of your radiator, turn slightly until you can hear air escaping. Once the air has escaped and some water emerges, which you can mop with the cloth, tighten the valve with the key again. Repeat on any other radiators experiencing the problem, and turn your heating back on. Hopefully, your radiator should begin to work normally again. For a detailed guide, see how to bleed a radiator.

Check the radiator valves

If you have tried bleeding your radiators to no resolution, check the radiator valves. As mentioned above, the thermostat valve can fail, so check this as well as the valve on the opposite end. If you have radiators without a thermostat, check each side and ensure the valves are open and not closed for any reason. If any of the valves are at fault, you’ll need to call a heating engineer to look this over and resolve it, replacing any valves where necessary.

Consider flushing the system

With the build-up of sludge in a radiator, you’ll want to remove this from the system, but how? The most effective way is to flush the radiator which should remove any debris that is preventing the radiators from heating up completely. A power flush may be a more effective solution with older systems, and this can be requested from a professional service to do.

Check for bigger issues

If there is no obvious reason for your radiators to not be heating up properly, this could be a bigger issue that needs resolving. Check that your boiler is working and that you have hot water from your taps. Are there any strange noises that can’t be attributed to trapped air? If you have tried bleeding the radiators already or have been doing this more regularly than needed, it could indicate a leak in the system somewhere. Check the pipes and valves and see if any water is leaking from obvious areas.

Why Are My Radiators Not Getting Hot After Trying This?

If in any case you are unsure of or can’t resolve cold radiators simply, it will require a heating engineer as soon as possible. They will hopefully be able to diagnose the problem and investigate more thoroughly, which is better than trying to fix it yourself if you aren’t entirely sure. If you discover a leak, for example, then it is best to leave this to a qualified professional. Turn off the valve that supplies the water to any leaking pipes, and if necessary, turn off the main water supply valve. This will stop the water from leaking and flowing through whilst waiting for a repair.

Hopefully, you have been able to resolve your cold radiator issue. If you have any queries or want to learn more about our range of designer radiators and more, please contact us.