8 December 2020

How to fix a pinhole leak in your radiator and copper pipes

A pinhole leak in your rads or pipes is an annoying problem. Not only can it cause your heating system to perform less efficiently, it can also lead to expensive water damage if left untreated.

In this article, we'll look at what causes a pinhole leak and how you can go about fixing it and solving the problem.

Table of Contents

What causes pinhole leaks?
How do you locate a pinhole leak?
How to fix a pinhole leak

Method 1 - Leak sealer
Method 2 - Radiator epoxy repair kit
Method 3 - Radiator & pipe replacement

How to prevent future pinhole leaks

What causes pinhole leaks?

If a central heating system is not regularly maintained, then corrosion can occur in your pipes and, in particular, your radiators.

Over time, tiny flakes of rusty metal can flake off into your system and settle at the bottom of radiators or certain areas in your pipework. These shards of rust compact and form a brown sludge which slowly eats away from the inside out.

If the problem is not dealt with then the corrosion eventually reaches the outside of your radiators or pipes, creating tiny holes from which water can leak.

How do you locate a pinhole leak?

The most common places you'll find a pinhole leak is in your radiators or in your pipes if they're made of copper. Below we'll look at signs of a leak in both instances and things for you to look out for.

Radiators

A pinhole leak in a radiator is usually easy to spot because there will usually be a wet spot on the floor underneath or you'll notice moisture on the underside of the radiator.

You might also notice that the bottom of the radiator is not getting hot due to a build up of sludge inside.

Copper pipes

Pinhole leaks in copper pipework can be much more difficult to locate as they could be occurring out of sight under a floor or in a wall.

These types of pinhole leaks can be the most dangerous as they are often not discovered until an expensive amount of damage has already been done.

Some tell tale signs that you have a leak in a copper pipe are:

Sudden increase in your water bills
Discolouration to your copper pipes - often green or black dots
Water marks on walls or ceilings
Moisture on exposed pipework
Dripping sounds

How to fix a pinhole leak

If you've discovered the leak and it really is just a tiny hole, there are a couple of routes you can take that will hopefully resolve the problem. Always make a note or take a photo of exactly where the leak was located, just so you can keep an eye on it in future and notice if it opens back up again.

Tools you'll need

Leak sealer solution
Water recepticle
Old sheet or towel
Radiator epoxy repair putty
Application spatula or matchstick
Sandpaper
Flat piece of cardboard

Method 1 - Leak sealer

A leak sealer is a solution that is poured into your heating system and provides a polymer seal over any pinhole leaks that have opened up in your radiators or pipes. This method is definitely not foolproof and will not solve the problem if the hole is too large so don't try this if you are not confident in your DIY abilities. However, if you're confident the hole is tiny, then this option could be worth trying.

Turn off the central heating system
Ensure your boiler is powered down and your central heating is switched off completely.
Shut off the water supply
Prevent potential water damage or flooding by closing the water supply line to your central heating system.
Drain the system
Locate the drain valve, typically found at the bottom of your boiler or lowest radiator, and open it to allow the system to empty fully.
Prepare the leak sealer
Mix the leak sealer as per the manufacturer's instructions. Carefully follow the directions to achieve the correct mixing ratios.
Add the leak sealer
Introduce the leak sealer mixture into the main return line of the system. Begin by pouring a small quantity into the pipe and observe its movement through the system. If satisfactory, continue adding the remainder until the desired volume is reached.
Refill the system
Fill up the central heating system with clean water once the leak sealer has been added. Turn the water supply back on and allow the system to fill back up.
Restart the heating system
Switch your boiler back on and restart your heating system. After the system is fully filled, bleed all radiators to ensure proper functionality.

Method 2 - Radiator epoxy repair kit

A two-part radiator epoxy is a type of putty that you can mix together and then apply to your radiator to block up the hole and stop the leak. It can also be used for other types of radiator damage like small chips or cracks.

Turn off your central heating system
Ensure your boiler and heating is switched off completely so that the radiator is not too hot to work on.
Clean the area around the leak
Give the area of the radiator around the leak a wipe down. Remove any dirt and remove as much moisture as possible. If the leak is very small, you can do this task without needing to drain your system.
Sand the area around the leak
Take a rough sandpaper and give a small rub to the area around the leak in order to roughen up the area. This will help the putty adhere to the radiator.
Mix the epoxy
On your flat piece of cardboard, squeeze out a pea-sized amount of both parts of the epoxy. make sure it's equal amounts of each. Take your mini spatula or matchstick and mix the two blobs together.
Apply the putty
Give the affected area of the radiator a quick wipe if necessary and then gently apply the putty to the pinhole leak with yout matchstick. Take your tie and carefully paste the putty on and around the affected area to seal up the hole.
Leave to dry
Depending on the manfacturer of the putty, it can take up to 24 hours to dry completely, so check the instructions and leave the putty to dry accordingly.
Check for leaks
Come back 24 hours later and feel with your hand across the radiator and check he floor for any signs of moisture. If there is still a leak you can try again and apply a little more of the putty and leave to dry.
Switch on your heating
Once you are happy that the leak has been sealed you can switch on your heating and check that everything is ok. Your radiator should be getting hot and no water should now be leaking out.
Paint the radiator (optional)
Depending on the brand, the putty that you've applied to stop the leak might be a different colour to the main body of your radiator. If this is the case, you might want to paint your radiator to make it more aesthetically pleasing. This is optional with the most important issue being that you've stopped the leak.

Method 3 - Radiator & pipe replacement

If your radiators or pipes have corroded so much that they are leaking then fixing with a leak sealer or epoxy is likely to only fix the problem temporarily. You may well have corrosion in other areas or the previously-fixed holes may corrode and reopen again.

If you know your radiators and pipework are old then you might want to consider having them replaced. While this does has an upfront cost, the potential water damage from leaky pipes and radiators could cost a lot more to fix, and would probably be considered an emergency.

If you do upgrade your rads and pipework, you'll probably notice your energy bills are cheaper as your system is running much more efficiently.

At Trade Radiators, our goal is to assist everyone in discovering the perfect radiator for any environment. Whether you seek a straightforward heating solution for a modest bedroom or desire to upgrade your outdated bathroom panel radiator with a stylish chrome towel rail, we've got you covered. Offering the most extensive selection of radiators available from any UK store, along with superior delivery services and our exclusive price promise, we strive to ensure that every room in the country receives the radiator it truly deserves. It all begins with understanding your requirements for a new radiator.

How to prevent future pinhole leaks

Now that you’ve put in the hard work to fix the pinhole radiator leaks, the last thing you want is the problem of corrosion to return in the future.

The best way to avoid your radiator to irreversibly rot from the inside is by ensuring that your heating system is well topped up with a chemical inhibitor. An inhibitor is a liquid solution that you can pour into your heating system which will stop internal rust and corrosion from occurring. The less corrsion that is going on inside your radiators, the less likely you are to experience pinhole leaks, radiators that are cold at the bottom and inefficient heating.

Another job you can have done every 3 or 4 years is to get a professional to powerflush your radiators. A cleaning solution is pumped around your heating system at high velocity, dislodging all the sludge and rust particles that has built up over time. It's a job that should be done by someone who knows what they're doing, but it's a great way to ensure your system is free of corrosion and is operating at maximum efficiency.

For all our products that will help keep your central heating system clean, please view our heating system accessories page.

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24 November 2023

How to fix a pinhole leak in your radiator and copper pipes

What causes pinhole leaks?

How do you locate a pinhole leak?