How To Fix A Radiator Leak In Simple Steps On Your Own

Many people nowadays use electric heaters, electric and oil-filled radiators to get warm. But classic radiators are one of the oldest and most effective ways of heating a home, having the ability to heat a space evenly and comfortably. Although these household appliances should be trouble-free for many years, they sometimes end up leaking. These leaks can result in many household problems, including inefficient heating, slip hazards and damaged furniture and flooring. 

water on wooden floor coming from leaking radiator

Have you noticed water puddling on or around your radiator? The sooner you deal with this problem, the better! Keep on reading to determine the source of the problem and follow our guide on fixing a radiator that leaks.

Why is your radiator leaking?

Wondering why your radiator is leaking? To help you figure out what’s causing the problem, here are some usual reasons why this is happening.

  • The radiator’s parts are damaged.
  • There are loose radiator pipe joints.
  • Corrosion caused by a build-up of sludge and debris.
  • Erosion caused by air coming into the system.

The most common cause of corrosion in your radiator is sludge, a mud-like substance that will build up over time if you don’t treat it. It can cause rusting. You can get rust off a radiator easily.  But, if you don’t, it will end up eating tiny holes in the radiator and result in leaks. Sludge can also cause damage to the boiler, pump and valves, and create blockages in the pipework and heat exchanger.

Determine the source of the leak 

Leaks are serious because they can do quite a lot of damage to furnishings and floors. Nowadays, there are different types of radiators installed on most central heating systems. The first thing you need to identify is where the leak is coming from. When you are dealing with small holes, it is difficult to pinpoint them. To locate the origin of the water leak, it is important to dry off the radiator completely. 

Step-by-step guide for a complete investigation

  1. Make sure to turn off the unit and then take a towel or an old rag and dry the radiator’s body.
  2. After you are done with the unit’s exterior, use some kitchen or toilet paper to check the leak source systematically. Wipe all parts one by one, such as pipes, joints and valves, and see if the paper gets wet. Use a different piece of paper for each area. This will help you to spot where the water is coming from easier. 
  3. Pay attention to places where valves and pipes meet. You can use an inspection mirror, which you can find at many hardware stores, to see around corners and in hard-to-view spaces.

 Female hand with rag cleaning water from heating radiator leak

What you’ll need

You’ll need a few household items and tools to help you find the heart of the problem. Make sure you’ve got all these to hand, so you won’t need to run off to find them when you’re in the middle of the job:

  • An old towel – to soak up water
  • A bucket – for water draining
  • Toilet or kitchen tissue – to identify the leak
  • Screwdriver
  • Spanner

Where the leaking water is coming from

If the radiator is leaking, this is probably coming:

  • From the body of the radiator, primarily because of too much mould.
  • From the radiator controls, meaning the bleed point and thermostatic valve. In the case of a leaking radiator valve, you will notice leaking from where it enters the radiator or another joint on the two nuts. It could also leak from the main body of the valve if it is damaged. This typically happens when the spindle packing, being inside, wears out with time.
  • From the pipes’ couplings and to the boiler or the feeder pipe that connects with the radiator. Pipes leak when they are split, broken or have a pinhole leak. The water can run down the water pipe and not be entirely visible for quite a long time. 

Step-by-step guide: How to fix a leaking radiator 

After you’ve identified what type of leak your radiator has, follow the right steps for each situation. You should prepare the room and the floor before moving on with fixing your unit. You should be ready for the worst-case scenario – water pouring out of your radiator. Take away any furniture around the unit and put some towels or any other absorbent material on the floor around the radiator. You should also have a large bucket to catch as much water as you can. You are now ready to get fixing your leaky radiator.

Gloves and repair tools near a leaking heating system. Accident of the heating system of a private house. Heating radiator.

Fixing a radiator spindle leaking

  • Tighten the gland nut using a spanner.
  • If the leaking doesn’t stop, undo the gland nut.
  • Wrap PTFE tape into the spindle.
  • Retighten the nut.

Fixing leaking from radiator body/Pinhole leaks

  • Turn off the boiler and allow enough time for it to cool down. 
  • Turn off the valves at each end of the radiator to relieve the pressure.
  • Remove the old radiator. Follow the instructions in your manufacturer’s manual. 
  • Use a non-acidic cleaner & flush out the system.
  • Replace with the new radiator.

Fixing leaking from radiator valve coupling nut

  • Drain the water’s heating system.
  • Loosen the nut between the radiator & the leaking pipe.
  • Remove the nut & fitting.
  • Take the olive off & replace it with a new one.

 Leaking heating radiator. Plumber with wrench repairs a leaking tap of a central heating pipe connection to a radiator.

Fixing a leaking radiator valve

  • Drain the leaking system below the leak.
  • Turn off both the supply valve & lockshield valve.
  • Catch any water that escapes with an old towel or in a bucket.
  • Use an adjustable spanner to undo the union nut.
  • Open the bleed valve to release the remaining water.
  • Wrap the valve tip with PTFE tape.
  • Re-tighten the union nut.
  • Open both the bleed & lockshield valves.
  • Allow the radiator system to fill up with water again.
  • Check for any leaks.
  • Close the bleed valve.

Fixing a radiator gland leak(under the plastic cap of the valve)

  • Turn on the radiator valve and wait to see if water leaks from underneath the plastic cap.
  • If it does, you should turn off the lockshield valve.
  • Remove the plastic cap and carefully unscrew the gland nut.
  • Wrap 20 cm of PTFE tape around the valve spindle.
  • Push some tape into the body of the valve, using a flat-headed screwdriver to force it.
  • Screw the gland nut back on and then replace the plastic cap on top.
  • Turn the valve back on.

Fixing radiator pipe joint leak

  • Drain the radiator to below the source of the leak.
  • Remove the nut from the leaking pipe with a spanner.
  • With the PTFE wrap around where the face of the olive meets the joint. 
  • Use your spanner to tighten the nut back up.
  • You can also add a plastic resin sealant to stem the water flow if you have a feed and expansion tank.

Preparing a home for the heating season in the cold time. Plumber with a wrench repairs a leaky heating radiator. Selective focus, close-up.

Is the radiator still leaking?

Despite the temporary fix, your radiator may be eroding, or a persistent leak can still occur. If that happens, you will have to consider getting a plumber or professional engineer to check your unit and even replace it. Removing a radiator and a new installation is not an easy or safe DIY process; that’s why we recommend you call a professional. That way, you will have a service well-done and no mess left behind. If you decide to change the radiator or valve alone, we still have some instructions for you. It is essential to predetermine which product is right for you. The new valve you’ll purchase must be the same as your existing one. Then you can follow these steps:

  • Drain the water from your heating system.
  • Unscrew the nuts that connect the water pipe to the valve with a spanner
  • Unscrew the old valve completely.
  • Clean the radiator valve threads.
  • Wind PTFE around your new adapter’s threads.
  • Screw it into the radiator.
  • Refill the central heating system & bleed the radiator to remove any trapped air.

When replacing a radiator that leaks, you should remember that bigger doesn’t necessarily mean better. Modern radiators can offer half your current rod size for just as much heat output. That way, you can reduce the cost of replacing a radiator and choose among sleek designs that will be more discreet in the home.

Man in work overalls using wrench while installing heating radiator in room. Young plumber installing heating system in apartment.

How to prevent radiator leaks

The best way to prevent radiator leaks is to follow routine maintenance. Although radiators are robust appliances, they are also hard-working and the main feature when it comes to our house heating. Offering them a little care, they can keep you feeling toasty for several years. Remember, the less efficient a radiator is, the harder your boiler has to work to heat it, which isn’t good news for your wallet. Here are some easy steps to care for your heat exchanger and avoid leaks in the future.

  • Don’t place any of your furniture too close to your radiators. This can damage your furnishings, but it can also stop heat from circulating properly. 
  • Your central heating system has a  chemical liquid that protects and prolongs its lifespan, called an inhibitor. Check the levels of the inhibitor regularly. Use a rust and corrosion inhibitor regularly.
  • It’s better not to dry clothes and towels on your radiators! This causes condensation and rust.
  • Check your radiators for cold spots, and if you find any bleed your radiator.
  • Inspect it frequently for any buildup that can clog your system and keep it from running correctly.
  • Use a leak sealer. This is a great product that can allow you to seal small, internal leaks as well as weeping joints. It will work best in warm circulated water and can be effective within 24 hours, depending on the leak’s severity.
  • Investigate signs of failure in the fixtures and pipe connections. That way, you will avoid more costly repairs in the future.
  • Use a radiator cleaner to clean the water routinely. This will help your radiator last longer.
  • Wipe down your radiator weekly to keep dirt and debris from accumulating on it. Wash it with plain water or a mild soap solution when you need to remove more difficult substances. Cleaning your radiator properly will save you money, energy and maximise the output of your heating system.

closeup to hand wearing a pink cleaning glove while cleaning the radiator with a rug
Running into a leaky radiator and a wet patch is one of the most annoying things that can happen. It is an issue that you should deal with relatively quickly if you don’t want the problem to worsen or ruin your floors. You should drop whatever you are doing and work fast to prevent irrecoverable damage to your furniture and flooring. Following our step-by-step instructions, you can help your home return to normal quickly!

Scroll to Top
Send this to a friend