Air in Radiators: Understanding the Causes and Solutions for Radiator Airlock
How does air get into your heating system?
There are quite a few different causes for this, especially if it becomes a recurring problem and bleeding your radiator isn’t helping. So let's go through each issue and see which one applies to you.Is air in the heating system normal?
Yes, it is just a normal side effect of heating and cooling water that comes from our mains pipes, which will contain some forms of dissolved gases. An easy-to-understand dissolved gas that we all know (carbon dioxide) is added to fluids to make them fizzy drinks. You could research more into this but it isn’t overly interesting so we will leave it there for this one and focus on some more meaty issues. For any system, annual maintenance should include releasing trapped air by bleeding radiators and valves near the heating system. If you'd like more information on this, check out our guide on how to bleed your radiators.Does installing new radiators introduce air to the heating system?
This is the most common cause of air in a system and has a significant impact. Once you break open the system, it is impossible not to add air. By removing or installing a new part, you’ll no doubt introduce air to the system. When you install a new radiator or replace a valve or any part of the heating system, while you’ll need to bleed the area for that specific part, you will also need to bleed all the radiators and any air vents near the boiler.Can leaks cause air in the system?
As surprising as it may seem, leaks can cause air to go into your central heating system. Think of a plastic bottle of water. Take the lid off and turn it upside down - the water will come out in a stream and will start to chug as air goes back into the bottle to replace the lack of atmosphere. The bottle can’t be empty as it either has to contain air or water. This can be a cause for the issue of recurring air in the system, so if you find yourself bleeding your radiators and system often, it could be a good idea to check for leaks. You can find out more on how to fix a leaking radiator which will help you identify where the leak is coming from.Can rust and corrosion cause air in a heating system?
Different types of metal behave differently when in water. With iron-based products such as steel radiators, when rust occurs hydrogen gas is released and an air pocket will form in the radiator over time. Where this is the cause, what you could find is one of two things:- Radiators are cold at the bottom
- When you bleed the radiators, the water that comes out is very dark