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Bubbling noises? Radiators that do not heat up properly? Chances are your central heating system contains air bubbles. The only thing for it is to bleed the system and top up the water level. Bleeding your heating system is very easy and will save you a nice packet. 

Air inside your central heating system 

Air inside your central heating system It is no more than normal for a central heating system to contain air bubbles. Sometimes some air got left when you last topped up the system, but the cause could just as easily be a leak or ducts that were poorly fitted. Bleeding your heating system is necessary to make sure your radiators work properly and to prevent ducts from oxidising. What is more, properly bleeding your central heating system will see you save a lot of energy. 

What do you need? 

  • a radiator bleed key or screwdriver
  • a tray (to collect small amounts of liquid)
  • a large towel 

Step-by-step plan to bleed your heating system 

  1. Set all radiator units wide open (maximum temperature setting) and make sure the boiler fires up so the water gets to circulate inside the ducts and the radiators. Leave your radiators to run at this maximum setting for at least 15 minutes.
  2. Now switch off your central heating system. This will stop any air or water from being pumped around the system. Then wait for at least 10 minutes to let everything cool down.
  3. Proceed to the radiator that is closest to the heating boiler, turn off the radiator valve and place the tray underneath the bleed valve. Be sure to keep a large towel handy.
  4. Position the screwdriver or bleed key onto the bleed valve and turn left until water comes out instead of air. Do not turn the valve open all the way, as chances are you will not be able to close it again.
  5. Close the bleed valve.
  6. Repeat the steps above for each radiator. Start out with the radiator nearest to the heating boiler and work your way up from the lowest floor to the top floor.
  7. Once all radiators have been bled, switch the central heating boiler back on.
  8. Check to see if the water pressure inside the central heating boiler is somewhere between 1.5 and 2 bar (the green part of the manometer). If the pointer has dropped to the red part, top up the boiler until you get back to the required pressure level. 

Need help? Call in a Vasco installation engineer 

Having trouble? Our installers are there to lend a helping hand! If you are seeing those air bubbles make a return after a short space of time, you may have a problem with the expansion vessel. In that case, the best thing to do is to get in touch with us to prevent your heating system from malfunctioning.

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