How to flush a central heating system

Over time, many central heating systems will gather debris and other unwanted materials throughout the various radiators and pipes in your home. As your system is always drawing in and circulating water, it is highly likely that your system will have at least some debris inside over sustained operation.

When this build-up becomes too great, the performance of your system can be adversely affected, resulting in loss of performance, unreliable heating, and other issues such as unwanted noise from your boiler or cold spots across individual radiators. This can be avoided through the process of flushing your system.

In brief, flushing a central heating system is the process of emptying the system of water and cleaning the interior. There are a number of ways to achieve this, the most common of which is ‘Powerflush’, which uses a device to do the vast majority of the work. Otherwise, you’ll need to manually flush the system yourself, which we will guide you through in this guide.

There are two main methods of flushing a central heating system - Powerflush, and manual flushing. Each has its own process, which we will walk you through in this section.

There are two main methods of flushing a central heating system - Powerflush, and manual flushing. Each has its own process, which we will walk you through in this section.

Powerflush is the process of using a specialised device to pump cleaning chemicals into your system, circulating them and removing the unwanted material from the system itself. The chemicals are pumped at a high pressure to ensure any rust, corrosion, sludge, or miscellaneous debris is effectively removed.

Generally, a Powerflush will take around 8 hours to complete fully, though a portion of this time is dedicated to the system pumping around the entire central heating loop. Particularly large or complex heating arrangements can take much longer to complete.

We do not recommend users to Powerflush a system, as it requires the use of specific chemicals for the job and a dedicated machine to do so. As this requires additional knowledge about your heating system, as well as complications from varying types of systems, this is best tackled by a trained heating engineer.

If you don’t have a Powerflush machine available, you can manually flush radiators individually to remove debris and improve performance. This can be particularly beneficial if you have only a specific radiator that is exhibiting poor performance.

This process is best performed by a professional engineer to ensure that your system is flushed effectively and with minimal complications.

To manually flush a radiator, you need to follow a number of steps:

Flushing a central heating system can be an involved and difficult task, though the benefits of doing so are absolutely worth it for the efficiency and long-term health of your home heating system. We do recommend contacting an accredited professional to perform this task where possible, as you will have added peace of mind in knowing the work is undertaken safely and effectively.