Radiator Leak

Our plumber fixing a radiator

Are you dealing with a radiator leak in your home? Don’t worry, help is at hand. With a few simple steps, you can address the issue and prevent further damage. Let’s explore how to tackle a radiator leak repair and restore optimal heating to your space.

A Guide To Fixing A Leaking Radiator

When you notice a radiator not heating up properly, it’s important to investigate the possible causes. One common culprit is trapped air at the top of the radiator or a build-up of sludge at the bottom. Additionally, leaks can occur in the radiator’s thermostatic valves, vent plug, or even the body if there is rust present. To address these issues, it’s essential to follow a systematic approach.

Common Causes of Radiator Leaks

Rust Pinhole:

A corroded pinhole refers to a small hole that develops on the surface of a radiator due to corrosion. This can occur over time as the radiator is exposed to moisture and oxygen. It is important to address rust pinholes promptly as they can lead to leaks and further damage if left untreated.

Radiator Thermostat Valve:

The thermostatic valve is responsible for controlling the flow of hot water into the radiator. If there is a leak in the thermostat valve, it can result in water seeping out and causing damage. Repairing or replacing the faulty valve is necessary to stop the leak and ensure the proper functioning of the radiator.

Radiator Spindle:

The spindle is a component that connects the radiator to the valve. It allows for the adjustment of the radiator’s temperature and can be operated using a valve key or a spanner. If there is a leak at the spindle, it may indicate a worn or damaged spindle seal, which requires replacement to prevent further leakage.

Radiator Gland Nut:

The gland nut is part of the leaking radiator valve spindle assembly and is responsible for sealing the connection between the valve body and the spindle. If the gland nut becomes loose or worn, it can result in a leak around the valve area. Tightening the gland nut or replacing the gland supply valve packing can help resolve the issue and prevent water leakage.

Joint and Seal:

The pipe joints and seals in a radiator system connect the pipes to the radiator and ensure a watertight connection. If there is a leak at a joint or seal, it can lead to water seepage. Repairing or replacing the faulty or leaking pipe joint or seal is necessary to prevent further leaks and maintain the integrity of the system.

Radiator Valve Coupling Nut:

The rad valve coupling nut is responsible for connecting the radiator valve to the pipe that supplies hot water. If there is a leak at the end of the radiator valve leak coupling nut, it can indicate a loose or damaged connection. Tightening the coupling nut or using a new sealing washer can help resolve the leak and ensure the proper functioning of the radiator.

How To Stop A Leaking Radiator?

If you notice a leak in your vehicle or radiator, it’s important to take prompt action. The method to stop a leaking radiator will vary depending on the source of the leak – whether it’s from the valve, pipe, or body.

We advise a lot of our customers to place a bucket underneath the leaking valve body to prevent further damage and to seek professional assistance if they are not comfortable handling the repair themselves.

It’s crucial to remember that radiators contain sludgy water, which can cause permanent stains on carpets if leaked.

To assist you in addressing the issue, our experts have compiled some helpful tips. Ensure you have the necessary tools, parts, an empty bucket, a dry towel, and Loctite adhesive. Additionally, having basic plumbing and central heating knowledge will come in handy during the process.

Identify Where The Leak Is Coming From

When you notice a leak, it is important to identify the source of the leak to effectively address the issue. Pinpointing the exact location of the leak is the first step in resolving the problem and preventing further damage. By identifying where the leak is coming from, whether it’s a rust pinhole, thermostat valve, spindle, gland nut, pipe joint leak sealer, or valve coupling nut, you can take appropriate measures to fix the leak and restore the functionality of your radiator.

How to find the source of your radiator leak?

If you haven’t decided yet to call out a professional, you can try some DIY tips to locate a leak yourself, if it is not obvious.

Make sure your rad is clean and dry by rubbing it down with your towel. This will make the leak easier to see, so you know where to start looking for that pesky trickle of water leaking from somewhere in its body.

Now take a small piece of toilet tissue paper and place it in one of three places: the body, the valve, the plastic cap, and the pipe, which brings water into your radiator.

Make sure you always have an empty bucket ready to keep your house safe from loading water.

Do not touch the leaking pipe area. If there is a leak in the body and you touch the paint, this can come off and will fold the whole room.

What To Do After You Located The Leak? – Prepare To Fix.

Once you have identified the location of the leak in the compression heating system of your radiator, it’s important to follow a few steps before you begin the repair process:

  1. Turn off the boiler: Ensure the boiler is switched off to prevent any hot water or heat circulating through the system while you work.
  2. Shut off valves: Locate and close all valves connected to the boiler. In a combi boiler system, the central heating flow and return valves are typically found on the left and right pipes.
  3. Drain the heating-plumbing system: Locate the drain cock and carefully drain down the water from the heating system. This will ensure that the radiator is free from any water pressure and is safe to work on.

With these steps completed, you can now repair the leak in your radiator. It’s always recommended to seek the assistance of a professional plumber if you’re not confident in repairing yourself.

If you have a system boiler:

Then you have to go up into the lof, find the F&E tank (the smaller one) and close the other water pipe where is the ball valve. This feed and expansion tank feeds the water to your radiators.

Radiator repair: ( DIY edition) – Fix A Leaking Radiator

Leaking Thermostatic valve:

If the TRV is leaking, try tightening it first. Often, the internal spindle packing can become damaged and cause leaks when the valves are partially opened or closed. Tightening the compression nuts or replacing the olive inside the valve can often resolve the issue. If these steps don’t work, you may need to replace the entire valve.

Replace the radiator valves:

To replace the radiator valves, ensure that the heating system has been drained. Loosen the compression nuts and remove the old radiator valve, placing a small bucket underneath to catch any remaining water. Don’t worry if the old olives are still on the 15mm pipe; replacing the new valve and applying a sealant such as PTFE tape or Loctite around the top of the olive will ensure a secure fit. Tighten the nuts to complete the installation.

Don’t worry about the old olives that are still on the 15mm pipe. If you don’t have an olive puller you never get this off. Just replace the valve and put some kind of sealant around the top of the olive (PTFE tape, Loctite). Tighten the nuts and you are ready.

Life hack :

If you tighten the nuts and you hear a squeaky noise then the valve will be leaking when you fill the system. It’s a saying but is true. If this happens undo everything and put plumbing sealant paste around the olive. Without any paste entering the pipes.

Remember, if you’re not confident in carrying out these steps, it’s advisable to seek the assistance of a professional plumber to ensure a proper and safe repair.

Fix a gland nut

This water leak can be found on top of the radiator head. Just be easy with this DIY fixing, don’t splash all the water on the ceiling.

You can slowly tighten and screw the gland nut together. Also, use sealing paste or PTFE tape. This solution is not always working but you can try it. If it doesn’t work, just replace the body of the valve or call a pro who will do the work for you.

Pinhole leaks – Rusty Body

If you notice a pinhole leak coming from the body of your radiator, it is most likely because there has been corrosion or sludge build-up. Pinhole leaks are very small but can lead to a huge leak. Do not touch the leaking rusty part. The paid can come off and the pinhole can get bigger in a matter of seconds.

Here are some tips and checks on how to replace the radiator:

Turn off the boiler and the valves underneath the boiler. Find the draincock and drain the system. Relieve the pressure by opening the bleed point on the top of the leaking radiator pipe. Put some towel underneath the radiator even knowing it’s empty.

Get some help, undo the Union nut quickly take off the radiator from the ball and flip upside down. You can avoid sludge going to your carpet.

After you can install the new brackets the replacement radiator and the radiator.

Pipe joint leak

If you notice water dripping from the joints, grab a spanner and tighten the Union nut. If this doesn’t work out, follow these steps:

  • Drain the central heating system water as we mentioned above.
  • Undo the union nut on the valves.
  • Undo the radiator valve tail and put sealant on it. This can be PTFE tape, Loctite or sealing paste.
  • Slowly put back the radiator valve tail and tighten it. Don’t over-tighten because the body of the radiator will crack.

Say Goodbye to Leaky Radiators with MML Plumbing’s Expert Repairs!


Are you struggling with a leaky radiator? Look no further! MML Plumbing is here to fix all your radiator woes. Our experienced team of plumbers specializes in radiator repairs and can quickly diagnose and resolve any leaks or issues you may be facing. We understand the importance of a properly functioning heating system, and we take pride in our efficient and reliable radiator repair services. With MML Plumbing, you can trust that your radiator will be in safe hands.

Contact us today and let us restore warmth and peace of mind to your home.

The most common radiator leaks:

The most common radiator leak is when the lockshield valve starts to drip. If you are lucky the compression fittings on the existing valve are loosened a bit. All you have to do to tighten up. But sometimes this is not working and you need to replace the whole valve.

Another reason for the leak is the case the bleed valve rubber or pin and sealed central heating system is damaged. This also can be replaced if you know how to drain the central heating system and fill it up properly without an airlock.

If you are not confident with this work, better to call a plumber now before you cause more damage than you. For the plumber, it is easier to diagnose the water leaks first than to fix someone’s messy job which could take double time.

A leak also can come from the body. If you see that the radiator body starts to leak, there is no other option you need to replace the whole radiator completely.

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