Ask the Expert: Dirt & Air Separation FAQs

In this Q&A feature, we sit down with Ed Morris, Technical Manager at Altecnic, to answer some of the most frequently asked questions surrounding dirt and air separation, exploring why it matters, the problems it helps prevent, and what installers and specifiers should consider when designing and maintaining modern systems

On this Page:

• Understanding Dirt & Air Separation
• Dirt & Air Separation for Heat Pumps
• Installation & Best Practice
• Maintenance & Servicing

Understanding Dirt & Air Separation

How do contaminants form within a system?

Contaminants can build up within a heating or cooling system from several different sources. Air can enter during installation, maintenance work, or through poor sealing over time. Once oxygen enters the system, it reacts with metal components and can begin causing corrosion within radiators, pipework, pumps, and heat exchangers.
As corrosion develops, sludge and magnetite begin circulating through the system water, while installation debris such as flux residues, jointing compounds, and pipework dirt can add to the problem. In hard water areas, scale build-up can also restrict flow and reduce efficiency, particularly around heat exchangers and hotter parts of the system.

How does dirt impact the system’s performance?

Dirt within the system can cause a wide range of problems over time, particularly within pumps, valves, and heat exchangers. Sludge and magnetite can restrict flow, affect valve operation, and even cause pumps to seize if left untreated. Dirt also reduces heat transfer efficiency, meaning the system must work even harder to achieve the same performance.

How can dirt and air be removed from the system?

The best approach is to continuously remove contaminants before they have a chance to circulate around the system and cause damage. Dirt separators remove sludge, debris, and magnetite from the system water, while air separators and de-aerators remove trapped air and microbubbles.
By maintaining cleaner system water, these devices help protect pumps, valves, and heat exchangers while supporting better circulation, improved efficiency, and long-term system reliability.

What are the different types of dirt and air separators?

There are several different types of dirt and air separation devices available depending on the application and the type of contaminants being targeted.
A non-magnetic dirt separator removes circulating dirt and debris by slowing the flow and allowing particles to settle within a collection chamber. Magnetic dirt separators go a step further by also capturing magnetic debris such as magnetite using a powerful internal magnet.
Air vents are designed to automatically release trapped air from the system, helping reduce noise and circulation issues, while de-aerators remove much smaller microbubbles and dissolved air to help improve long-term system performance.

What are the benefits of dirt and air separation?

Effective dirt and air separation helps improve overall system efficiency by maintaining cleaner water quality and better heat transfer throughout the installation. It also helps reduce corrosion, wear, and damage within key components such as pumps, valves, and heat exchangers, supporting more reliable long-term system performance.

Dirt & Air Separation for Heat Pumps

Do heat pump systems need dirt and air separation?

Absolutely! Heat pumps are particularly sensitive to poor water quality because they often contain smaller waterways and operate at lower temperatures for longer periods. Any sludge, debris, or trapped air within the system can quickly affect efficiency and performance. Effective dirt and air separation helps protect key components such as heat exchangers and circulating pumps, while also helping maintain reliable long-term operation.

Learn more about our Heat Pump Protection Solutions 

Installation & Best Practice

Where should a dirt separator be installed?

In most heating systems, dirt separators are typically installed on the return pipework before the boiler or heat pump. This allows the device to capture debris and magnetite before contaminants reach critical components such as pumps and heat exchangers. It is very important that you correctly position a dirt separator, as it helps maximise separation performance and improves the system’s long-term performance.

See our range of Dirt & Air Separation Solutions

Can dirt and air separators reduce system call-backs?

Yes, they can play a significant role in reducing ongoing maintenance issues and unnecessary call-backs. Many common problems installers encounter, such as noisy systems, poor circulation, blocked components, or inefficient operation, can often be linked back to poor water quality or trapped air within the system.
By helping maintain cleaner system water, dirt and air separators support more reliable operation and reduce the likelihood of performance-related issues developing over time.

Maintenance & Servicing

How often should a dirt separator be cleaned or blown down?

There’s no single answer because every system is different, but there are some good general maintenance guidelines installers can follow.
For new systems, I’d recommend carrying out an initial blow down after the first week or two of operation. On retrofit projects or dirtier systems, it’s worth checking and cleaning much sooner. Ongoing maintenance will then depend on overall system condition, although many systems may only need cleaning a few times per year once the water quality has stabilised.

How do you clean a magnetic dirt separator?

When cleaning a magnetic dirt separator, the key thing is to remove the magnet before opening the purge valve. This releases any captured magnetite so it can be flushed safely from the system. Once the debris has been discharged and the purge valve closed, the magnet can simply be reattached and the separator returned to normal operation.