🕑 8 minutes read

Radiators are essential for maintaining warmth and comfort in our homes, especially during the colder seasons. They are an integral part of our home heating systems, working to distribute hot water or steam throughout our living spaces.

When a radiator starts to leak, it can cause inconvenience and even damage your home. That moment when you see water coming from your radiator or a puddle on the floor can be concerning. Is a leaking radiator considered a home emergency?

Let's find out.

Is a Leaking Radiator a Home Emergency?

An engineer is checking a leaking radiator

A leaking radiator inspection by a professional engineer

The short answer is it depends. A small drip or minor leak may not be considered an immediate emergency, but it should still be addressed as soon as possible to prevent further damage. However, if you notice a large amount of water leaking from your radiator, it is important to take immediate action. First, shut off your heating system and arrange for a repair or replacement.

Ignoring a leaking radiator can result in significant water damage to your home's interior.

While you can delay the repair, preventing water from pooling under the unit is important. Use towels or buckets to collect the water, or turn off the water valve to avoid further damage. A leaking radiator can decrease your home's heating efficiency, potentially causing higher energy bills. If left unaddressed, it can harm your walls, floors, and furniture. Therefore, it is best to call professionals to address radiator leaks as soon as they are detected.

Water is eaking from a radiator

A leaking radiator

What Causes a Radiator to Leak?

A leaking radiator can be attributed to various potential causes. Some common causes include rust or corrosion, mineral deposits, and damaged or worn-out gaskets or seals.

Over time, these issues can develop due to wear and tear, poor maintenance, or external factors such as harsh weather conditions.

A leaky radiator valve

Radiator valves are more important in modern heating systems. A common reason for finding a wet patch under your radiator is a faulty radiator valve. If the internal parts of the valve wear out, it can lose its watertight seal, leading to water leakage. At times, you may need to replace the thermostatic radiator valve due to water leaks causing damage to the existing one.

Changing the heating temperature of a radiator

Adjusting radiator

Typically, the leak occurs when the valve is partially open. You can test if the valve is the issue by turning it off (closed), drying the water with a towel, and checking if the area around the valve stays dry. If water leaks when you open the valve again, you likely need to replace the valve, a relatively straightforward task.

A corroded radiator

A radiator can rust and corrode over time, especially if it's old and you haven't regularly added a chemical inhibitor to your heating system. A chemical inhibitor is a liquid that helps prevent internal corrosion. Severe corrosion can lead to small holes at the bottom of the radiator, causing brownish water to leak out. While these holes start small and may initially show minor leaks, they can become a bigger problem. The rust-filled water can stain carpets and become frustrating.

A corroded radiator

An old rusty radiator

“If you notice a hole in your radiator, the best solution is usually to replace it with a new one.”

Loose or damaged radiator spindle

A loose or damaged spindle, which is the connection between the main part of the radiator and the radiator valve, can lead to water leakage. To address this, tightening the gland nut usually resolves the issue, as it may have become loose over time. If the water leakage persists, using PTFE tape around the spindle is another common solution.

You can explore detailed knowledge of Thermostatic Radiator Valves (TRVs) by checking out our blog.

How to Fix a Radiator Leak

A new radiator installation in a London property

A new radiator installation

Fixing a radiator leak will depend on its cause. If the issue is with the gaskets or seals, these can often be replaced without having to replace the entire radiator.

However, if the leak is due to rust or corrosion, it may require a professional assessment and possibly a replacement of the affected part.

If you notice a small leak, you can try using radiator sealant as a temporary fix until a professional can address the issue. Remember, this is only a temporary solution and should not be used as a long-term fix.

Locate the Leak

To begin repairing a radiator leak, identify the source of the water escape. Ensure the radiator is completely dry using an old towel, taking care not to burn yourself. Turn off the central heating system and let the radiator cool down before wiping it with a clean, dry paper towel. Concentrate on potential leak areas like the body, control valve, and connector pipe. If the paper becomes wet over one of these parts, you've found the leak source.

Drain the Radiator An engineer is draining a radiator

Unlock the bleed valve on a radiator

Some repairs may require draining the radiator, especially when replacing parts or accessing internal components. Drain the radiator if tightening the union nut doesn't work or if you need to replace the radiator valve. Follow these steps to drain your radiator:

  • Turn off the radiator and let it cool for 30 minutes to an hour.
  • Close the control valve and note the thermostatic valve setting (if applicable).
  • Locate and close the lockshield valve on the radiator's bottom.
  • Use pliers or an adjustable spanner to remove the control valve, allowing the unit to drain into buckets placed beneath the valves.
  • Release the bleed valve with a radiator key to ensure the radiator is empty.
Identify and Repair the Leak

Once the radiator is drained, pinpoint the leak location and initiate the repair process. Common repairs include tightening the union nut, replacing faulty valves, or fixing other damaged components.

Refill and Bleed

After repairing the leak:

  1. Refill the radiator.
  2. Open the control valve and lockshield valve, restoring the thermostatic valve to its previous setting. If you drained the system completely, refill it with water using a hose or bucket.
  3. Bleed the radiator by releasing air through the bleed valve until water flows consistently.
Check for Leaks

Turn the heating system back on and monitor the radiator for any signs of new leaks. Ensure that all connections are secure and that the repaired components function correctly. If the repair was successful, your radiator should operate without further issues.

Common Damage Caused By Radiator Leaks

If you're tempted to simply mop up a bit of water every now and then instead of fixing your leaking radiator, think again.

Here are some of the issues that a leaking radiator can cause

Flooring Damage: Leaking radiators can harm your flooring.

Structural Risk: If not addressed, leaks may extend to lower parts of your home.

Electrical Hazard: Water reaching electrical points poses a risk.

Reduced Heating Capacity: Leaks can negatively impact your radiator's BTU heat output.

Higher Energy Bills: Poor heating efficiency from leaks can lead to increased energy costs.

How To Fix a Pinhole Leak In a Radiator

Repairing a pinhole leak in a radiator involves addressing slow leaks caused by tiny holes in the radiator body or pipes. They develop gradually due to corrosion in the heating system or grime buildup inside the water pipe. If the radiator body leaks, replacing the entire unit might be necessary, but there's a temporary fix to prevent further water damage.

“A leak sealer designed for radiators can be used for central heating systems.”

  1. If you have a freestanding radiator, opt for an epoxy sealing solution. Choosing the right sealant is crucial to avoid harming the entire system.
  2. After sealing the holes, it's recommended to contact a professional heating engineer to replace the unit eventually. For top-notch heating systems, explore the best quality radiators.

How To Fix a Leaking Radiator Valve

There are two common reasons for water leaking: a loose gland nut or degraded spindle packing.

Standard for hot water radiator valves

Radiator Valve

Lockshield spindle


Here's how you can fix a leaking radiator valve

  1. Remove the valve cap from the control valve to expose the valve shaft (spindle).
  2. Locate the gland nut around the spindle. If the leak is due to a loose gland nut, use a spanner or wrench to tighten it.
  3. If tightening the gland nut doesn't stop the leak, the issue may be damaged spindle packing. Remove the gland nut to inspect the spindle packing.
  4. To seal the spindle, wrap it with PTFE tape and press it into the space around the shaft.
  5. Replace the nut and the valve cap.

Following these steps can help resolve a leaking radiator valve caused by common issues like a loose gland nut or damaged spindle packing.

How to Fix a Radiator Pipe Joint

Repairing a leaking valve tail or radiator pipe joint is a straightforward process. If you notice water pooling beneath your radiator due to a leaking pipe joint or if water is dripping from the control valve at the bottom, you can follow these steps to fix it:

Chrome 15mm Radiator Valve Pushfit Elbow Adaptors

Radiator pipe joints

  1. Drain your radiator (follow the steps mentioned above).
  2. Use the bleed valve to ensure the radiator is completely empty.
  3. Remove the radiator valve coupling nut or the union nut from the leak's location.
  4. Apply PTFE tape around the olive (on the tail) or the pipe joint connecting to the water pipe.
  5. Replace the nut and tighten it using a spanner or wrench.

If the leakage persists, you might need to replace the existing valve with a new component for a more effective solution.

Once you've identified and addressed the radiator leak, make sure to tighten all valve connections. Reopening the valves is crucial to enable water flow through the unit.

Next, switch on your central heating and carefully inspect the radiator valve and body for any indications of a leak. Keep in mind that it might take some time for a leak, especially a pinhole leak, to become noticeable.

“If the leakage in the radiator pipe joint persists despite your efforts, we advise you to seek professional assistance to repair or replace the radiator.”
A radiator in a London home

Can I Stop My Radiator from Leaking by Turning the Water Off?

While turning off the water supply to your radiator may temporarily stop the leak, it will not solve the underlying issue. It is best to call a professional engineer to treat the leak immediately to prevent further damage and ensure your radiator is functioning efficiently.

Call Professionals for Radiator Leak Repair

If you notice a leak in your radiator, it is best to call in experienced professionals who are knowledgeable in handling these types of issues.

At Serviceteam, our team of experts offers reliable boiler repair, installation, and maintenance services across London and its surrounding areas. We understand the importance of a properly functioning heating system and can quickly and efficiently address radiator leaks to ensure your home stays warm and comfortable.

Don't hesitate to contact us for all your radiator repair needs.