Reasons your radiator may feel cold this winter and how to fix the issue

A chilly radiator can very quickly turn a cosy home into an uncomfortable one.

Understanding the reasons behind a cold radiator is crucial to resolving the issue and restoring warmth to your home.

In this guide, MyJobQuote.co.uk delves into the common causes of cold radiators as well as providing you with some practical solutions and tips on how to maximise your heating system’s efficiency.

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Radiator Feels 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 cold-bottomed radiator is a build of sludge and debris. Due to radiators being a constant damp environment, over the years, we often see a buildup of debris, which is an accumulation of dirt and rust.

Over time, this accumulation can begin to restrict and block the flow of hot water, causing parts of the radiator to lack the ability to heat. Due to a blockage, water is redirected to other parts of the radiator, meaning the bottom may not be reached by the flow of hot water.

How to Fix This Issue

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.

Let your heaters run for around an hour before flushing it out and replacing the water. Flushing your radiator out will involve removing your radiator from the wall, so if you are not comfortable doing this yourself, always call a professional to carry out the task.

Usually, a chemical cleaner will get the job done in an hour or so. However, if you're dealing with a huge buildup of sludge, you may want to leave your chemical cleaner in your radiator for up to a week before flushing. This will give the cleaner time to break down all of the dirt and debris that has collected over the previous years. Always remember to flush the radiator and replace the water after a chemical clean to ensure your radiator is safe for use in your home.

If you’re against using a chemical cleaner and would rather go down an eco-friendly, non-toxic route, you can opt to remove your radiator and clean it yourself. In preparation for cleaning your radiator you should first isolate your radiator by closing the lockshield valve to avoid any excess water leakage. Make sure your central heating system is switched off, and the water inside has been left to cool fully. Allowing the interior water to cool completely before cleaning will avoid any serious injury. To close the lockshield valve, it may be necessary to use a spanner. If you have a thermostatic radiator valve (TRV), turn this down to zero. If your radiator does not have this function, you will need to turn a second valve on the opposite end with a spanner.

Next, you'll need to empty out the water inside your radiator, so prepare your surroundings in case of spillage. Ensure your flooring is waterproof, and if not, lay down towels and keep buckets handy. Use a bleed key to open the valve at the top of the radiator. This will allow airflow to move through the system, and water will begin to pour from loosened valves.

Once water has stopped pouring from the valves, disconnect the radiator from the wall and pour the remainder of the water out. Ensure you don't fully undo any valves while disconnecting the radiator, as this can cause water to flow from your central heating system, which may flood your home. Use a hose to give your radiator a quick blast, which should shake and remove any remnants and debris from the interior pipes. Ensure the water runs clean, and then reattach your radiator to the wall, attach the fixtures, and turn all valves back to their original positions. Once the water begins 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 a power flush. A power flush is a process that is best left to the professionals, as it requires specialist equipment. Power flushing your radiator is a great process for those looking for multiple radiators to be cleaned. Power flushing is basically the same process as cleaning an individual radiator. However, a specialist will push water and cleaning chemicals at a high pressure through your central heating system to clean out the entire structure. If more than one of your radiators is acting up, this may be the best option for you.

Radiator Feels Cold at The Top

If your radiator feels cold at the top but there is still warmth at the bottom, this is usually due to trapped air in the radiator. The trapped air can prevent the hot water from circulating properly. This then results in a cold top section and a warm bottom section.

How to Fix This Issue

The best thing you can do to fix this issue is to bleed the radiator. Take the steps below to properly 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.

The Entire Radiator Feels Cold

If the entire radiator feels cold, this can be due to several problems. Below is a list of the potential causes for this issue and how to fix each one:

Thermostatic Valve Malfunction

A faulty thermostatic valve can prevent hot water from flowing through the radiator. To fix this issue, check the valve’s setting. Make sure it is not set too low or is accidentally turned off. If the valve is malfunctioning, it may need to be replaced.

Blocked Pipe

A blockage in the pipe supplying the radiator can restrict the flow of hot water. A professional plumber can use specialised equipment to identify and clear any blockages.

Pump Problems

A weak or faulty pump may not be able to circulate hot water effectively throughout the system. A qualified heating engineer can diagnose and repair or replace the pump.

Boiler Issues

A malfunctioning boiler may not be producing enough heat to warm the radiators effectively. Consult a professional heating engineer to identify and resolve any boiler issues.

Low Water Pressure

Low water pressure can affect the boiler’s ability to heat water efficiently. Be sure to check your water pressure and consult a plumber if necessary.

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Below is a list of tips on how to make your radiators work more efficiently:

Invest in Radiator Reflectors

Radiator reflectors are relatively cheap and easy to install. They are fitted behind the radiator and help to ensure that heat isn’t wasted by passing through the wall behind the radiator. Instead, these handy devices ensure that as much heat as possible is reflected back into the room.

Place a Shelf Above The Radiator

A shelf above the radiator can help to reflect the heat back out into the room. It can also prevent heat from rising and becoming lost up in the ceiling. Instead, the warm air will be pushed out into the room. Shelves above the radiator are especially useful when combined with reflectors.

Bleeding The Radiators

One of the best ways to improve the efficiency of your radiators is to bleed them. This process involves opening the bleed valves and releasing any trapped air in your radiator. This will help to get rid of any cold spots on the radiators and ensure that the system can run to its full potential, increasing the efficiency of your heating system.

Clean The Radiators Regularly

You must ensure that the airways between the fins are clear. The space between the fins attracts light dirt and dust, which can block the airways and reduce the circulation of warm air. Cleaning the entire radiator, including the space between the fins, can help to improve the circulation, allowing your radiator to radiate more heat.

By understanding the common causes of cold radiators and implementing the suggested solutions, you can effectively address the issue and ensure optimal heating performance.

Remember, regular maintenance, such as bleeding radiators and cleaning filters, is crucial for maintaining a well-functioning heating system. If you're unable to resolve the issue yourself, consult a qualified heating engineer for professional assistance.

By taking these steps, you can enjoy a warm and comfortable home, even during the coldest winter months.

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