An airlock in your heating system can be removed easily by bleeding the radiators. Doing this will force the airlock out of the system, so you should attempt this task on all your radiators, including the ones that are cold all the way through and cold at the top.
Will an Airlock Eventually Clear Itself? Sometimes, small airlocks may clear themselves as water circulation continues with one or more radiators. However, larger airlocks often require manual intervention, like bleeding the radiators or using a hose to release the trapped air.
In order to clear the airlock and restore your radiators to full functionality, you may need to bleed the radiators. Bleeding radiators involves using a radiator key to open the valve at the top of the radiator and allowing trapped air to escape until water flows out.
The best way to clear the airlock is to temporarily pressurise the pipe from above - preferably with water (but this is not always possible given the circumstances) so high pressure air will suffice. The object is to ensure that you do not have a bubble of air, trapped between two bodies of water.
Insert your radiator key into the valve and gently turn the release valve. Carefully twist it anti-clockwise the radiator will hiss as the air is slowly released. Water can also spray out of the radiator so be prepared. If the release valve accidentally comes out, use an adjustable spanner to replace.
Open the garden hose connection cap and fill the radiator with coolant. If there is still air at the flush con- nection, use the Radiator Pressure tester to push the air out of the heater core. When coolant flows out of the fixture, seal the garden hose opening. Release the tester, and check for proper coolant level.
Use the radiator key to loosen the lockshield valve and then tilt the radiator to get rid of any excess water. Use the radiator key to close the bleed valve. Remove the radiator from the wall. Take the radiator to an outside space to clean, using a hose to flush any dirt and residue through manually.
Place a container below the valve to catch water and have a towel ready. Slowly open the valve; some water may drip, but any trapped air will also be released. You will likely hear a slight hissing sound when you first loosen the valve, which is an excellent sign that trapped air is being removed from the system.
Make sure you achieve a good seal to prevent pressure from escaping. Turn on the hot water for a few seconds, then the cold water, and keep both on for about a minute. Now, turn off the cold water then the hot water tap. Water will fill up inside the hose and pressure should build up to break the airlock.
Open the filter valve
Many (but not all) central heating systems have a filter, which water continually cycles through to remove impurities. They also double up as drainage valves, and are perfect for relieving pressure in the system.
An airlock in your heating system can be removed easily by bleeding the radiators. Doing this will force the airlock out of the system, so you should attempt this task on all your radiators, including the ones that are cold all the way through and cold at the top.
To manually remove an airlock, disconnect the discharge hose and let the pump run until water flows steadily. Reconnect the hose and ensure all connections are tight. You may also need to open valves to release trapped air.
Turn on your main water valve and listen for the sound of air escaping from the open faucets. Let water run for about 10–15 minutes or until the flow becomes steady without sputtering. Once the flow has stabilized, turn off your faucets. Check that your toilets have refilled properly and flush them again if necessary.
Use the radiator key, attach it to the bleed valve, and rotate anticlockwise not more than half a turn. After doing this, you will hear a hissing sound, indicating that the trapped air is escaping. This will guarantee that all the trapped air has been released.
There are a couple of ways that you can clean the sludge out of your heating system. The first is called a powerflush, which is both the name of the method and also a physical device that your heating engineer will use. Alternatively, you can take every radiator off one at a time and flush it yourself.
Look at the hoses and determine which way the coolant normally flows. Disconnect the hoses and back flow it the opposite direction of the normal flow with the garden hose. Gently blow the water out with compressed air, repeat the back flush and compressed air treatment several times.
To remove the air you have to “burp” the system. Typically any air in the system will collect in the side stream filter or pot feeder. This can be opened and filled to just slightly overflowing to remove as much of the air as possible.
Common causes of air in radiators: Low water pressure, leaks in radiators, and heat pump problems. Symptoms of air trapped in radiators: Noisy operation, uneven heating, and frequent bleeding requirements. Maintenance tips: The importance of frequent radiator bleeding and annual servicing.
Even a small amount can create air pockets which prevents proper circulation of coolant. Signs and symptoms of radiator airlock include: Overheating during normal driving. Heater not functioning correctly.