In a domestic heating system, particularly those using water as a heat transfer medium, a deaerator plays a crucial role in maintaining efficiency and performance. The primary function of a deaerator is to remove dissolved gases, primarily oxygen and nitrogen, from the water circulating within the heating system. Here’s how it works and why it is important:

1. Understanding Dissolved Gases:

When water is heated, it can hold dissolved gases such as oxygen and nitrogen. These gases can enter the system through various means, including micro leaks and connection points. Over time, if not managed properly, these gases can accumulate and lead to several issues.

2. Impact of Air on Heating Systems: 

The presence of air in heating systems can cause significant problems:

• Corrosion: Oxygen is particularly harmful as it promotes corrosion within metal components of the heating system, such as pipes and radiators.

• Noise: Nitrogen can lead to noise issues within the system, causing irritating sounds from radiators and other components.

• Reduced Efficiency: Air pockets disrupt the flow of water, leading to inefficient heat transfer and cold spots in radiators.

3. How Deaerators Function: 

Deaerators work based on principles derived from Henry’s Law, which states that the amount of gas dissolved in a liquid is proportional to its partial pressure above that liquid. By reducing pressure or increasing temperature within the deaerator:

• Dissolved gases are expelled from the water.

• The deaerator allows these gases to be vented out of the system before they can re-enter.

4. Benefits of Using Deaerators: 

Installing a deaerator provides several benefits for domestic heating systems:

• Improved Efficiency: By removing air from the system, deaerators enhance heat transfer efficiency, ensuring that more energy is used for heating rather than being lost due to air interference.

• Longer Equipment Life: Reducing corrosion leads to less wear on components like boilers and radiators, extending their lifespan.

• Quieter Operation: With reduced air pockets, systems operate more quietly without the disruptive noises associated with trapped air.

• Better Chemistry: The operation of a deaeration device leads to a phase change from Ferrous Oxide (rust) to Ferric Hydroxide (salt), raising the fluid’s pH to 8.2 and helping maintain clear system water.

5. Application in Domestic Settings: 

In typical UK homes using boiler + radiator systems (which account for 89% of homes), incorporating these devices (for air removal) helps maintain optimal performance by addressing both air and dirt accumulation.

In summary, a deaerator effectively removes dissolved gases from water in domestic heating systems, thereby preventing corrosion, reducing noise levels, and enhancing overall efficiency.