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    How to repressurise a Worcester boiler

    If your boiler isn’t working as it should be, or you’re left without heating and/or hot water, you may need to repressurise the system. Thankfully you shouldn’t need to call in an engineer as this is a fairly quick and easy job that you can do yourself. However, Worcester Bosch boilers are repressurised in a slightly different way to other types of modern combi boilers. So, it is important that you know exactly what to do to repressurise your boiler safely and effectively. 

    How will I know if my boiler pressure is low? 

    The first indicator that your Worcester boiler pressure is low will be if your central heating or hot water isn’t functioning properly. To find out for sure though, you should check the water pressure gauge on the front of your boiler. This gauge will either be in the form of a hydraulic dial or a digital reading. Normally, your gauge should sit between 1 and 1.5, but if it’s reading less than 1 bar, your boiler pressure is too low and requires repressurising. 

    What causes boiler pressure to drop? 

    There are two main causes when it comes to your boiler losing pressure. Firstly, any leaks in the system can result in a loss of water pressure, so be sure to check around your pipes, radiators, and boiler for any sign of a leak or damp areas. Remember to never look inside your boiler yourself though, only a Gas Safe engineer should do this. If you do find a leak around any part of your heating system, contact an engineer as soon as possible to help. 

    Also, bleeding your radiators can sometimes cause a loss of boiler pressure, so you should repressurise it each time after you bleed your radiators. 

    How to repressurise your Worcester boiler 

    Repressurising your boiler simply means to allow more water to enter the system. A lot of other combi boilers use a filling loop to achieve this, but some Worcester boilers use an internal filling key. Before you repressurise your boiler, don’t forget to turn off your electrics and double check the manufacturer’s booklet to ensure everything goes smoothly. 

    • Take off the hatch on the underneath of your boiler, you will find the internal Worcester filling key clipped inside. 
    • Find the filling link in the newly opened boiler. This is a small hole slightly to the right of a white square in which the key will slot into. 
    • Firmly push the Worcester boiler key into the filling link until the arrow on the side of the key nearly touches the black plastic. 
    • Rotate the key anticlockwise until the arrow is facing towards you. 
    • Carefully turn the white square clockwise to enable cold mains water to enter the system. You will probably hear this. 
    • Wait for the pressure to get between 1 and 1.5 on the pressure gauge. 
    • When it has, rotate the square back to its original position and turn off the water. 
    • Place an old towel under the boiler to catch any water spills before turning the filling key back around and removing it from the boiler. 
    • Dry off the key and put it back in the tray and then put the hatch of the boiler back into place. 
    • Turn the boiler back on and press the reset button if needed. 


    Contact National Boiler Spares today if you need help finding the right parts for your boiler.