Radiators get air locked most commonly due to excess water vapor building up in the heating system as water heats. This vapor, less dense than water, can become trapped, usually at the highest points like radiators, preventing hot water from circulating properly.
Here's a more detailed explanation:
- Water Vapor Formation: As your central heating system heats water, some of it turns into vapor. This is a natural process.
- Air Trapping: Because water vapor is less dense than water, it tends to rise and collect at the highest points in your system, like the top of radiators.
- Restriction of Water Flow: This accumulation of air (or water vapor) creates an "airlock," a bubble that obstructs the flow of hot water into the radiator. As a result, the radiator may feel cold, partially heated, or make gurgling noises.
- Contributing Factors:
- Corrosion: Corrosion within the system can produce hydrogen gas, contributing to airlocks.
- System Design: Heating systems with long pipe runs or multiple levels are more susceptible to airlocks.
- Refilling the System: When the system is refilled (after repairs or draining), air can be introduced.
- Low Water Pressure: Insufficient water pressure can make it easier for air to accumulate.
Consequences of Air Locks:
- Inefficient Heating: Radiators won't heat properly, leading to cold spots and increased energy consumption.
- Noisy Radiators: Trapped air can cause gurgling, banging, or hissing sounds.
- System Damage: In severe cases, airlocks can contribute to corrosion and damage to system components.
Prevention and Solutions:
- Regular Bleeding: Bleeding radiators (releasing trapped air) is a simple maintenance task to prevent airlocks.
- System Inhibitors: Using chemical inhibitors in your heating system can help prevent corrosion and the formation of gases.
- Automatic Air Vents: Installing automatic air vents can automatically release trapped air from the system.
- Professional Servicing: Regular servicing by a qualified heating engineer can identify and address potential issues before they lead to airlocks.
