How To Bleed Radiators With A Combi Boiler


Learn how to efficiently bleed radiators with a combi boiler for optimal heating performance. Follow our step-by-step guide and top tips!
How To Bleed Radiators With A Combi Boiler

Mastering the Art of Radiator Bleeding for a Cosy Home

Radiators play a crucial role in keeping our homes warm and comfortable, especially during the chilly months.

But what happens when your radiators aren't performing as they should?

One common issue is air trapped within the system, causing cold spots and reducing efficiency.

Fear not, as we unveil the easy solution – bleed radiators with a combi boiler.

Get ready to learn the ropes and reclaim warmth for your home.

Why Radiator Bleeding Matters

Before delving into the process, let's understand why bleeding radiators are essential.

Over time, air can accumulate within your radiator system, preventing hot water from circulating effectively.

This trapped air forms bubbles that rise to the top of the radiator, creating cold patches.

As a result, you may notice certain areas of your home not heating up adequately, leading to discomfort and increased energy bills.

Tools of the Trade

To embark on your radiator bleeding journey, you'll need a few essential tools:

  1. Radiator Key: This specialized key is designed to fit into the bleed valve, allowing you to open and close it with ease.
  2. Cloth or Towel: Keep a cloth or towel handy to catch any water that may drip during the bleeding process.
  3. Bucket: While not always necessary, having a bucket nearby can help contain any excess water.
  4. Combi Boiler: Ensure your combi boiler is switched off before starting the bleeding process to avoid any accidents.

Step-by-Step Guide to Radiator Bleeding

Now that you've gathered your tools, it's time to roll up your sleeves and get started.

Follow these simple steps to bleed your radiators like a pro:

  1. Turn Off the Heating: Begin by switching off your combi boiler. This step is crucial for safety reasons and allows the system to cool down before bleeding.
  2. Identify the Bleed Valve: Locate the bleed valve on your radiator. It's typically located at the top of the radiator on one of the sides.
  3. Prepare the Area: Place your cloth or towel beneath the bleed valve to catch any water droplets.
  4. Use the Radiator Key: Insert the radiator key into the bleed valve and slowly turn it anticlockwise. You should hear a hissing sound as the trapped air escapes.
  5. Release Trapped Air: Keep turning the key until water starts to trickle out steadily. This indicates that all the trapped air has been released.
  6. Close the Valve: Once water begins to flow consistently, quickly close the bleed valve by turning the key clockwise to prevent water wastage.
  7. Check Other Radiators: Repeat the process for all the radiators in your home, starting from the ground floor and working your way up.

Top Tips for Effective Radiator Bleeding

To ensure optimal results, consider the following tips:

  • Regular Maintenance: Make radiator bleeding a part of your routine home maintenance to prevent issues before they arise.
  • Check for Leaks: Keep an eye out for any leaks or dripping water around the bleed valve, as this could indicate a problem with the valve or radiator.
  • Monitor Pressure: After bleeding your radiators, check the boiler pressure gauge to ensure it remains within the recommended range.
  • Seek Professional Help: If you encounter any difficulties or notice signs of a more significant issue, don't hesitate to seek assistance from a qualified heating engineer.


Bleeding radiators with a combi boiler is a simple yet effective way to optimise your heating system and enhance comfort in your home.

By following the steps outlined above and incorporating regular maintenance into your routine, you can ensure that your radiators operate efficiently, keeping you snug and warm throughout the year.

Say goodbye to cold spots and hello to a cosier living space!