How to Fix a Leaking Radiator in Five Steps

Radiators are important in keeping your home warm and toasty when it's cold outside. But if you switch on your unit, there's nothing worse than hearing the faint dripping sound of water escaping. Luckily, you don't need to be a rocket scientist to repair your radiator on your own - sometimes, there'll be a fairly simple fix.

If you're wondering how to fix a leaking radiator at home, you've come to the right place. But before you can enjoy indoor heating again, you'll first need to understand why your radiator is leaking and what you'll need to repair it. It's also wise to know when you can fix it yourself and when you need to call in a professional.

Our simple guide will help walk you through the process, step-by-step, to ensure that you're staying warm all year long.

Why is my radiator leaking?

Before fixing your radiator, you need to understand where the problem lies.

Damaged or loose valves

The most common cause of radiator leaks is a damaged, loose, or faulty valve. As your radiator ages, it undergoes a certain amount of wear and tear. This is also true for all the smaller components of your sealed central heating system, like the valves.

When a radiator valve's seal begins to deteriorate, it allows water to escape. And the worse the deterioration is, the worse the leak will be. In this case, you'll need to replace the damaged valve.

In some cases, you may need to tighten the valve. They may have become looser over time. Or if it's a new radiator, it may not have been installed correctly.

Rusted radiator

Most homeowners aren't aware that their radiator has a lifespan of around ten years. And, when radiators become older, they are more susceptible to rust and corrosion. When rusted radiators are left unchecked, they can form small holes in the pipes and body of the unit. This leads to radiator leaks and potential damage to your flooring.

Rust is also more common in units with no rust and corrosion inhibitor added to its water.

The easiest way to know if corrosion is causing a radiator leak is by checking the drops or puddles of water left behind - as rust usually causes the water to go a muddy-brown colour.

Damaged or loose unit connection

Lastly, a damaged or loose connection between the valve and the radiator unit can cause slow leaks. A leaking radiator valve spindle can usually be tightened. But, in the case of severe damage, it may need to be replaced.

Five steps for fixing a radiator leak

1. Find the source of the radiator leak

Before you can get to work repairing a radiator leak, you'll need to locate where the water is escaping from. To do this, you'll first need to dry your radiator completely. You can do this with an old towel, being careful not to burn yourself.

It's best to turn your central heating system off and wait for the radiator to cool down before you start. However, it's important to still take caution when wiping it down.

Once the radiator is dry, wipe a piece of clean, dry paper towel over the unit. Make sure to concentrate on parts of the unit that are most likely to leak. These parts include the body, control valve, and connector pipe.

If the paper becomes wet when wiping it over one of these parts, you've likely found the source of your leak. When you have successfully isolated the site of your radiator leak, you can start the repair process.

2. Drain the radiator

Some repairs may require you to drain your radiator. Typically, this step is taken when parts need to be replaced or when you need access to internal parts of the unit. You will need to drain your radiator if:

Tightening the union nut doesn't work

  • You need to replace the radiator valve

    How to drain your radiator

    Turn the radiator off and allow the unit to cool down to avoid injury. This may take between thirty minutes and an hour.

  • Close the control valve on your radiator. If you have a thermostatic valve, take note of its setting to restore it once repairs are completed. You can also consult your heating system's manual to ensure the thermostatic valve is set correctly.

  • Find and close the lockshield valve on the bottom of your radiator. Some older unit models may not have this component.

  • Remove the control valve from your radiator using pliers or an adjustable spanner. When the valves are removed, the unit will begin to drain. So, be sure to have buckets beneath the lockshield and control valves to prevent water pooling.

  • The bleed valve removes air from the unit and allows the water to drain. Use your radiator key to release the bleed valve. To ensure your radiator is empty, you can also lean your radiator to the side.

    3. Fix the radiator leak

    Fixing a pinhole leak in the radiator body

    A pinhole leak is exactly what it sounds like. It's a slow leak caused by minute, pin-sized holes in the body or pipes of the radiator unit. These leaks typically develop over time and are caused by corrosion within your heating system. A grime build-up inside the water pipe may also cause a pinhole leak.

    If the body of your radiator is leaking, you'll likely need to replace the entire unit. But there's also a temporary fix you can use to prevent further water damage before you're able to replace it.

    You can use a leak sealer for radiators that are part of a central heating system. However, if you have a freestanding radiator, you'll need to apply an epoxy sealing solution. Using the correct sealant on your unit is essential to avoid damaging the entire system.

    Once you've sealed the holes in your radiator, you'll need to contact a professional heating engineer to replace the unit. If you want the best heating system in your home, you can check out PlumbNation's range of exceptional radiators.

    Fixing a leaking radiator valve

    If you checked your radiator for moisture and found a leaking valve, there may be two explanations for the escaping water. A radiator valve leak may be explained by a loose gland nut or deteriorated spindle packing.

    Luckily, both of these problems have the same simple solution. To fix a leaking radiator valve, you need to:

    Remove the valve cap from the control valve. Once the lid is removed, you should see the valve shaft (spindle).

  • Locate the gland nut. It's found around the spindle. If the cause of the leak is a loose gland nut, it must be tightened with a spanner or wrench.

  • If the leak continues after tightening the gland nut, the cause is most likely damage to the packing material around the spindle. You can remove the gland nut to assess the spindle packing.

  • To seal the spindle, wrap it with PTFE tape and press it into the space around the shaft. Then, replace the nut and the valve cap.

    Fixing a leaking valve tail or radiator pipe joint

    A leaking radiator pipe may also cause water to pool beneath your radiator. If you spot dripping water coming from the bottom of the control valve, you will need to add PTFE tape to the leaking pipe joint. Alternatively, the leak may come from the valve tail, where the control valve connects the radiator's body.

    Whether you have a radiator pipe joint leak or tail leak, you can use the same steps to fix them.

    Drain your radiator (see steps above)

  • Use the bleed valve to ensure the radiator is empty

  • Remove the radiator valve coupling nut or the union nut from the leak site

  • Wrap PTFE tape around the olive (on the tail) or the pipe joint where it connects to the water pipe

  • Replace the nut and tighten it using a spanner or wrench

    If the leak continues, you may need to replace the existing valve with a new component.

    4. Turn the radiator on and check for leaks

    After you've located the source of the radiator leak and applied the fixes, ensure all the valve connections are tightened. Opening the valves again is also important to allow water to flow through your unit.

    Then, turn on your central heating and check your radiator valve and body for any signs of a leak. It may take some time before the leak becomes apparent, especially in the case of a pinhole leak.

    However, if the unit continues to leak, it may be time to call a professional to repair or replace it.

    5. Call a professional

    In the case of a pinhole leak, you'll need to call a professional heat engineer - even if you've applied a temporary fix. And if you've checked the control and bleed valve on your unit and still find your radiator leaking, it may need replacement parts.

    The cost to fix your radiator may vary depending on what needs to be replaced. Generally, replacement parts are inexpensive. But you may rack up a higher bill if you need to replace the entire unit.


    Leaking radiator FAQs

    How long does a house radiator last?

    The lifespan of an average radiator is around ten to twenty years. Its longevity is influenced by its maintenance levels and the quality of the unit. It's recommended to replace outdated radiator models due to the safety concerns they raise. Additionally, finding replacement parts for older models may make repairs more costly.

    Is a leaking radiator in my house an emergency?

    A leaking radiator isn't necessarily a cause for concern. In most cases, radiators leak due to loose or damaged connections. Most of these problems can be fixed at home without needing a professional heating engineer. However, if your radiator is leaking excessively, it's best to turn your heating system off and schedule a repair or replacement of your unit.

    If a leaking radiator is left unchecked over a long period, it can cause severe water damage to the interior of your home. So, while you can wait to have your radiator repaired, you shouldn't allow the water to pool under the unit. You can use some old towels or buckets to catch the water or turn the water valve off to prevent further damage.

    Can you fix a leaking radiator at home?

    Leaking radiators are easy to fix - particularly if the cause isn't linked to corrosion or a damaged unit. While you may need a few tools and replacement components, you can fix a leaky radiator in a matter of hours.

    If you're not comfortable attempting the repair yourself, or if you have pinhole leaks or a leaking pipe, you'll need to consult a professional. While using a plumber may cost a little extra, you can rest easy knowing the job has been done right.

    Can I stop my radiator from leaking by turning the water off?

    Stopping the water supply to your radiator is a simple temporary solution to prevent further water damage in your home. But if your radiator is leaking, you'll need to repair it before turning the water back on.

    Once you've turned the water off, the radiator will continue to leak until the water level in the unit is lower than the leak itself. In the meantime, you can place a bucket or container under the site to catch any excess water.