What to do if your boiler loses pressure

If you're experiencing issues with your boiler, then it could be down to your boiler pressure. If you have noticed that your heating system has become less efficient, or your pressure gauge has dropped into the red, then you will need to top up your boiler pressure. 

How to repressurise your boiler

Topping up your boiler pressure is a simple fix and can be carried out without a heating engineer. First of all identify what sort of filling system you have and then follow the instructions, or watch our technical trainer show you how its done.

External Filling Loop

You'll be able to identify if you have an external filling loop, because there'll be two valves; one from the mains cold water and then a second valve which is connected to the heating system. 

  • Attach the hose to each side of the valve and open the mains cold tap.
  • Open the second tap which allows water in to the heating system 
  • Watch the pressure rise and stop once the bar reaches just about one and turn off both taps
  • Remove the taps from the hose, there will be some water drip out so be mindfull


external filling loop
keyed filling loop

Internal Filling Loop (Keyed)

Locate the key this will usually be on a flap underneath the boiler or it may have been provided you as part of the installation

  • On the front right hand side you'll notice an open black port and this is where the key fits
  • You'll notice a picture of an open padlock and a closed padlock and on the white key there is an arrow on the shaft, align the arrow with the open padlock as you push it up into the open port
  • Turn the key and watch the pressure rise to just over one bar
  • Turn the key back to the open padlock and remove. Be mindful of any water dripping 


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Keyless Internal Filling Loop

A keyless filling loop is easily identifiable, as you'll see a blue lever at the bottom of your boiler

  • To repressurize the system with the keyless filling link simply pull down the blue lever
  • Once the pressure has increased to over one bar, release the lever


keyless filling loop

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