Why Do My Radiators Keep Filling With Air?


For homeowners who rely on a central heating system, radiators play a crucial role in providing warmth and comfort during colder months. However, one common and frustrating issue that many individuals encounter is the continuous accumulation of air within their radiators. This article aims to explore the reasons behind this problem and provide practical solutions to help address it.

  1. Inadequate Initial Bleeding: One of the primary causes of air accumulation in radiators is inadequate bleeding during the initial installation or after maintenance. When a radiator is not bled properly, air pockets can get trapped within the system. Over time, these air bubbles rise to the top, displacing water and hindering the efficient circulation of heat. Regular bleeding is necessary to remove air and allow for proper radiator functioning.

  2. System Refills and Maintenance: During system refills or maintenance activities, such as replacing a boiler or repairing a pipe, air can enter the system. It is important to ensure that the system is bled afterward to eliminate any air pockets. Neglecting this step can lead to recurring air accumulation and reduced heating performance.

  3. Corroded Pipework or Radiator Valves: Corrosion within the pipework or radiator valves can create tiny gaps or holes, providing entry points for air to seep into the system. Over time, these small air leaks can accumulate and cause airlock within the radiators. Regular inspection of the pipework and valves, along with prompt repairs or replacements, can help prevent air infiltration.

  4. System Imbalance or Insufficient Pressure: An imbalanced heating system, where some radiators heat up more quickly than others, can be an indication of air accumulation. Uneven heat distribution often occurs when radiators are not adequately filled with water due to low system pressure. Checking the pressure gauge and adjusting it to the recommended levels can help resolve this issue and ensure proper water circulation.

  5. Cold Feed Water: The temperature of the incoming water supply can also contribute to air accumulation in radiators. If the cold feed water is particularly cold, it can cause the warm water inside the radiator to cool rapidly. This cooling effect can result in air pockets forming within the system. To mitigate this, consider using a thermostatic mixing valve or a similar device to regulate the temperature of the incoming water.

Resolving the Issue: To address the persistent air accumulation in radiators, the following steps can be taken:

  1. Regular bleeding: Routinely bleed radiators, especially during the start of the heating season, to remove trapped air and allow efficient water circulation.

  2. Thorough system maintenance: When performing system refills or maintenance tasks, ensure that bleeding is part of the process to eliminate any introduced air.

  3. Inspection and repair: Regularly inspect pipework and radiator valves for signs of corrosion or leaks. Promptly repair or replace any damaged components to prevent air infiltration.

  4. System balancing: Check the pressure gauge and adjust it to the recommended levels. Proper system balancing will ensure even heat distribution throughout the radiators.

  5. Temperature regulation: Consider installing a thermostatic mixing valve to control the temperature of the incoming water, preventing rapid cooling and subsequent air accumulation.

Persistent air accumulation in radiators can be a frustrating issue that hampers the performance of the central heating system. By understanding the underlying causes and implementing appropriate solutions, homeowners can maintain a well-functioning heating system. Regular bleeding, thorough maintenance, inspection for corrosion, system balancing, and temperature regulation are all essential steps to prevent and resolve the problem of air accumulation in radiators, ensuring a comfortable and efficiently heated home.

right icon
Back to blog

Heating Help

Tips for purchasing, setting up, and upkeeping your radiators and towel rails.

Expert Advice

Our experienced team provides expert advice on all aspects of home heating.

Inspirational Designs

Discover tips from actual customers to inspire and enhance your heating experience