How to Clear An Airlock in Your Central Heating System

When it comes to fixing central heating issues in your home, in most instances, you will have to utilize the services of a professional Gas-Safe registered technician. However, there are specific jobs that are relatively simple and can be performed by any homeowner, and clearing an airlock in your central heating system is one of those jobs. 

Radiator Bleeding Key

What Is An Airlock?

An airlock is the terminology used to describe a situation where vapour becomes trapped within the heating system. One of the main symptoms of this problem will be that the hot water will be prevented from circulating, which will ultimately mean that the radiator will not heat up. 

Your central heating system works by circulating hot water around the home, but an inevitable side-effect is that excess water vapour can be created as the water is heating. Because this gas is not as dense as water, much like steam coming out of a kettle, it will rise to the highest point within your system. This is an airlock, and it has the potential to cause a range of different problems within your central heating system.

Some of these issues might include water not flowing out of your taps or radiators remaining cold even when the boiler is operating at full capacity. This not only increases your energy bills, which are already high enough, but it also means that your property will remain cold in the winter months, as the central heating is not functioning properly. 

Read: Expansion Vessel – All You Need To Know

How To Resolve The Problem of an Airlock in Your Central Heating System

The easiest way to remove an airlock from your central heating system is to bleed the radiators. Bleeding a radiator is not as painful as it sounds and requires a simple radiator key tool that can be bought in any DIY store. The key to this process is to bleed every radiator in the house regardless of whether they are hot or cold. This is because the central heating system is a sealed system, so there is a possibility that air could be trapped in numerous locations. 

Let’s walk through the entire process of clearing the airlock. 

  1. Switch off your central heating system, and ensure that you wait a total of twenty minutes before moving forward to the next step. This is important as you need to ensure that the system has cooled down properly before beginning the bleeding process. 
  2. There is a strong possibility that some water will escape from the radiator during the process, so put some towels down on the floor underneath the radiator to catch any spilled water and protect your flooring. 
  3. Take the radiator key mentioned above and slowly open the valve, which is typically found at the top of the radiator on the left or right-hand side. Turn the valve in an anticlockwise direction. As you turn the key, you should hear a distinct hissing sound: the air escaping from the radiator – this is precisely what you want. 
  4. Wait for either the hissing to stop or some water to come out of the valve. Once this happens, that is the signal that all of the air has been released from the system.
  5. Close the valve again by turning it clockwise and ensuring it is properly closed. 
  6. Repeat this process across all of the radiators in your home.
  7. Check the boiler pressure; it is entirely possible that you will have low boiler pressure after completing this process. If this is the case, refer to your boiler manual to find out how to restore the pressure to the correct levels. 
  8. Now turn the heating on, give the system a few minutes to power on, and check your radiator for cold spots. 

How to remove an airlock from your hot water system

If your heating system is functioning perfectly, but water is not flowing out of your taps, then you most likely have an airlock in the hot water system. Once again, this should not present too much of a problem and should be a reasonably easy fix. 

  1. The first part of the process, and a very important one at that, is to turn off your mains supply. Find the stop cock, which is most properties is located underneath the sink. Normally this tap should be turned clockwise to turn off the water supply to your property. 
  2. Now that there is no water coming into your home, go upstairs and turn on all of the taps. Work your way downstairs, ensuring that you do not miss any taps. These include the downstairs toilet taps and bath taps and showers, which people sometimes forget. At some point, all of the taps should run dry as there is no new water coming into the property. 
  3. The next part of the process involves flushing all of the toilets until there is no water left in the tanks. Once this step is complete, you are halfway through the process. 
  4. Go back upstairs and turn the taps in the entire house so that if water were running, it would only be trickling out of the tap. 
  5. Turn the stopcock anticlockwise so that the water supply is flowing back into the house. 
  6. Once the water is flowing out of all the taps, turn all of the taps so the water is coming out at around 50 percent of the capacity. After approximately five minutes, turn all taps on fully.

ADI Leak Detection are a leak detection company providing the above information to hep your with central heating problems, another related problem would be a boiler losing pressure.