How to Fix a Leaking Radiator Valve?

A leaking radiator spells bad news for you and your home. 

Not only could you be left without an efficient heating system, but neglecting a leaky radiator can cause it to get worse over time- and it could get to the point where serious overheating occurs which can be dangerous.

As well as this, not promptly fixing a leak may result in needing the radiators to be fully replaced – a more costly solution than simply dealing with the leak when it occurs.

A leaking radiator valve is one of the most common places for a leak to occur, and it’s important you know how to fix it.

Not only will it save you the cost of calling out a plumber, but knowing how to fix a leaky radiator valve will allow you to solve the problem swiftly and avoid further issues from occurring. In this blog, we’ll outline how to fix a leaking radiator valve.

What is a radiator valve?

It’s important to fix a leaking radiator valve as soon as possible, but before we examine how to do so let’s take a closer look at what one actually is.

Radiator valves are easily identifiable and can be found at the bottom of your radiator. Usually a twistable mechanism, they allow you to control how much heat a radiator emits. Depending on the temperature of your home, you’ll be able to increase or decrease how hot a radiator is.      

How to locate a radiator leak?

It’s important to be sure that the source of your radiator leak is the valve before you get to work attempting to fix it.

Before you start, give the entire radiator a rub down with a towel to dry it. This will mean you won’t be confused about where the leak is coming from. 

Next, use three pieces of toilet paper or kitchen roll and place them on the main body of the radiator, the radiator valve and the pipe that transports water to the radiator. 

You’ll then be able to spot the source of the leak based on which paper is becoming wet.          

What do you need to fix a radiator valve?

If you’re fixing a leaking radiator valve, you should prepare beforehand by making sure you have the right equipment to handle the problem.

You don’t need any specialist equipment, just a few household items will do. 

These include:

  • A towel
  • A bucket
  • Toilet paper or kitchen roll
  • A screwdriver 
  • A spanner

Once you’ve got your equipment ready, you can begin to fix a leaky radiator valve.   

How to fix a leaking radiator valve?

There can be a number of reasons why your radiator valve is leaking, and each cause will require a different approach. 

Leaking from the radiator valve nut

In most cases, the leak will be from the radiator’s valve nut. This is perhaps the easiest and simplest leak to fix. There will be three of these nuts on your radiator valve, and usually, you can stop the leak by tightening the nut with a spanner.  

If this doesn’t work, you may need to add some plumbing jointing compound on the leaking nut. To do this you’ll need to drain the central heating system, take the nut off the valve by turning it anti-clockwise with a spanner, add the jointing compound and then reapply the nut. Once you’ve done this you can refill the central heating and check to see if the leak has gone. 

Leaking radiator valve gland

A leaking valve gland is also a fairly easy fix. 

First, you should attempt to tighten the gland nut with a spanner. However, if this doesn’t stem the leak then you can wrap PTFE tape around the valve threads. Again, drain the central heating system, remove the gland with a spanner, wrap PTFE tape around the threads, refit the valve gland and check for leaks. 

Leaking radiator drain valve 

If it’s a leaking radiator drain valve, you will most likely need to replace the valve’s rubber washers. These washers can get damaged if tightened too much on the drain valve. 

To stop a radiator drain valve from leaking, start by draining the central heating system. Then, remove the head of the radiator drain valve with pliers. Remove the rubber washer and apply a new one, refill the central heating system and check the leaks have gone.

Leaking radiator bleed valve

In this scenario, you’ll need to replace the radiator bleed valve. In some cases, the bleed screw may be bigger than the nut, and you can try adjusting it with a spanner. If that doesn’t work, you should once again turn to PTFE tape. First, close both radiator valves. Then, open the bleed screw by using a bleed key to release the pressure and use a bucket to catch any leaking water. Remove the radiator bleed valve or screw and add some jointing compound or PTFE tape. You can then refit the bleed valve, refill the system, bleed the radiator and check the leak has stopped.     

Leaking due to corrosion

If there is corrosion in your valve, or the broader radiator, there is very little that can be done. This typically occurs when sludge inside the radiator causes it to rot from the inside, causing holes that make the system leak. In these instances, you’ll almost certainly need to replace the radiator. In the short term, you can use a plastic resin sealant to stem the leak, but this isn’t a permanent solution. You should also not use sealant if you have a sealed central heating system.  

How to prevent a leaky radiator valve 

Prevention is always better than cure, and there are a number of steps you can take to ensure your radiator does not leak. 

These include:

  • Don’t place furniture too close to radiators- not only can these cause damage to your furnishings, but the pressure and weight on the radiator and its valves can cause leaks.
  • Check inhibitor levels regularly- radiator inhibitor is the chemical that protects your central heating system. Check it on a frequent basis to ensure longevity. 
  • Don’t dry clothes or wet towels on radiators- while it may not seem like a big deal, this can actually encourage corrosion and rust.   
  • Check radiators for cold spots- On a monthly basis check there are no cold spots on your radiator. These can develop into problems that may cause leaks later on so if you notice any cold spots, it’s a sign you need to bleed your radiator.