Why Every Central Heating System Should Have a Deaerator

Air is one of the biggest hidden enemies of any wet central heating system. While many homeowners recognise the importance of magnetic filters for removing sludge and debris, far fewer understand the benefits of removing dissolved air from the system.

A deaerator is designed to continuously separate and remove microscopic air bubbles from the heating water before they become a problem. Whether you have a gas boiler, heat pump, or commercial heating system, installing a high-quality deaerator can improve efficiency, increase reliability and extend the life of the entire system.

What Is a Deaerator?

A deaerator is a specialist component fitted into the heating pipework, usually on the flow from the boiler where the water temperature is highest.

As heated water travels through the system, dissolved gases naturally come out of solution, forming tiny microbubbles. A deaerator slows the water flow through an internal chamber, allowing these bubbles to combine into larger bubbles that rise to the top and are automatically vented from the system.

Unlike standard automatic air vents, a deaerator continuously removes even the smallest microscopic air bubbles before they circulate around the system.

Why Does Air Cause Problems?

Even a small amount of trapped air can create several issues, including:

• Cold spots on radiators

• Noisy pipework

• Gurgling sounds

• Reduced circulation

• Poor heating performance

• Increased energy consumption

• Pump cavitation

• Internal corrosion

• Premature boiler component failure

  
  

Air also introduces oxygen into the heating water, accelerating corrosion of steel radiators, pumps, valves and heat exchangers.

The Benefits of Installing a Deaerator

Improved Heating Efficiency

Without trapped air restricting circulation, hot water flows more evenly throughout the property. Radiators heat up faster, temperatures become more consistent and the boiler operates more efficiently.

Reduced Corrosion

Removing oxygen dramatically slows corrosion inside the heating system. This helps protect:

• Boiler heat exchangers

• Radiators

• Circulation pumps

• Pipework

• Motorised valves

• Underfloor heating manifolds

  
  

Less corrosion also means less magnetite sludge forming over time.

Quieter Heating System

Air is responsible for many of the clicking, banging and gurgling noises homeowners experience.

A deaerator quietly removes these air pockets, creating a smoother and quieter heating system.

Longer Equipment Life

Modern boilers contain narrow waterways and highly efficient stainless steel or aluminium heat exchangers.

Keeping the water free from oxygen and air bubbles reduces wear and helps expensive components last longer.

Lower Running Costs

An efficient heating system requires less energy to maintain comfortable temperatures, reducing gas or electricity consumption over time.

Deaerator vs Automatic Air Vent

Many people assume an automatic air vent performs the same job, but there is a significant difference.

An automatic air vent removes large pockets of trapped air that reach the vent.

A deaerator removes microscopic dissolved air continuously throughout normal operation, preventing larger air pockets from forming in the first place.

The two components work together but perform different functions.

Deaerator vs Magnetic Filter

These products complement each other rather than compete.

A magnetic filter removes:

• Magnetite sludge

• Iron oxide

• Rust particles

• Installation debris

  
  

A deaerator removes:

• Dissolved oxygen

• Microbubbles

• Entrained air

  
  

Together they help maintain clean, healthy system water while protecting every component.

Ideal for Heat Pumps

Low-temperature heating systems such as air source heat pumps rely on excellent water circulation.

Because heat pumps operate continuously for long periods, any trapped air can significantly reduce performance.

Installing a deaerator helps maintain efficient circulation and supports lower running costs.

Best Time to Install One

A deaerator can be fitted during:

• Boiler installations

• Heating system upgrades

• Boiler replacements

• Power flushing

• Major heating repairs

• Commercial plant room refurbishments

  
  

It is particularly beneficial when replacing an older boiler with a modern high-efficiency appliance.

Combine with Good Water Treatment

For the best long-term protection, a deaerator should be combined with:

• A magnetic system filter

• Chemical inhibitor

• System flushing where required

• Water quality testing

• Correct system pressure

• Annual boiler servicing

  
  

This approach helps comply with BS 7593:2019 recommendations for maintaining domestic central heating systems.

Professional Installation Matters

Correct positioning is essential for maximum performance. The deaerator should be installed where water temperature and flow conditions allow the greatest amount of dissolved air to be separated.

An experienced heating engineer will ensure it is fitted in the optimal location and that the entire heating system is balanced and operating efficiently.

Looking After Your Heating System

Investing in good water quality such ass VDI 2035 or following BS7593:2019 is one of the smartest ways to protect your heating system. While boilers often receive the attention, the condition of the system water has an equally important impact on efficiency, reliability and lifespan.

At LHS Plumbing Services, we recommend a complete approach to system protection that includes water quality testing, magnetic filtration, chemical treatment and, where appropriate, the installation of a deaerator. These measures help keep your heating system running quietly, efficiently and reliably for years to come.