Slow Leak In Central Heating System

Tuesday 18th August 2020

Your central heating system is an essential part of your home, without it, you can say goodbye to hot water and heating! So when you discover a slow leak in your central heating system, it can be alarming.

A leaking boiler isn’t something that will go away on its own, so if you spot something, it’s important to get it fixed as soon as possible. Left alone, a leak will continue to worsen, potentially causing damage to components, your electrics and your home. 

Finding out what’s causing your slow leak can help you get your central heating fixed quickly, allowing things to carry on as normal in your home.

Below you’ll find some of the causes of a slow leak in your central heating system and information on what to do next.

fixing a slow leak

Causes of boiler leaks

Most of the causes of boiler leaks are pretty common, and could be the result of one or more causes, including:


If your pipes have begun to corrode due to wear or a leak, you may need to have parts replaced. Corrosion can also be the result of a boiler that hasn’t been installed properly. This is an issue that needs to be fixed as soon as possible to stop it spreading to other parts of your boiler.

Excess pressure

If your boiler pressure is too high (anything above a 2), this can cause water to leak, particularly where there may be underlying issues with worn parts within your boiler. Releasing some of the excess pressure can help bring your boiler back to within the 1-2 range.

Poor pipework

If your boiler wasn’t fitted correctly, dodgy pipework can lead to leaks. This will likely be the case with a new boiler, although older boilers can show signs of poor fitting over time too. 

Issues with the heat exchanger

Your heat exchanger within your boiler is responsible for heating your hot water. If this becomes damaged or defective, it can cause the water in the tank to overheat and leak. This could cause an injury due to the temperature of the water.

Checks you can make

If you’ve spotted a leak coming from your boiler, you can do some investigations yourself to find out the cause. 

  • Visually check your pipes to identify an obvious leak, as this could point to an error with the pipes themselves.
  • Check your pressure gauge. If the pressure is above 2, release it to bring it back down. You might also need to bleed your radiators. If the leak continues, there could be another reason behind it.

Next steps

Some slow leaks can be rectified yourself, such as excess pressure within your boiler. However, it’s best to bring in professionals to make sure there isn’t a serious underlying cause behind your leak and to make sure it’s repaired safely and correctly.

Only a Gas Safe Registered Engineer should carry out any work and repairs on your gas central heating system. Do not attempt to fix the problem yourself.

For professional plumbing services in Leicestershire and Derbyshire, contact us at Lonsdale Plumbing today. As experts in central heating and all plumbing repairs, we can tackle your slow leak and get your boiler fixed in no time.