How to Check & Repressurise Your Gas Boiler
When to do this: If your heating or hot water has stopped working and the boiler is showing a fault code. Low pressure is one of the most common causes of boiler shutdowns.
Steps:
- Check the pressure gauge on the front of the boiler, usually a circular dial with green and red zones. When the system is cold, pressure should sit between 1 and 1.5 bar (in the green zone). If it's below 1 bar, you need to repressurise.
- Switch the boiler off and allow it to cool before doing anything else.
- Find the filling loop, which is a flexible braided metal hose (or sometimes a copper pipe) that loops underneath the boiler, with a small lever or tap at each end.
- Open both valves by turning the handles so they run in line with the pipe. You'll hear water entering the system.
- Watch the gauge and close both valves as soon as the pressure reaches around 1.5 bar. Close them firmly, one at a time.
- Restart the boiler. You may need to press the reset button to clear the fault code.
If you find yourself repressurising regularly, there may be a leak somewhere in the system. Call a Gas Safe registered engineer to investigate.
How to Thaw a Frozen Condensate Pipe
When to do this: In cold weather, if the boiler has stopped and is making a gurgling noise. This usually means the condensate drain pipe, which carries wastewater from the boiler to an outside drain, has frozen.
What you'll need: A kettle, watering can, or hot water bottle filled with warm (not boiling) water.
Steps:
- Locate the condensate pipe, a plastic pipe (usually white or grey) running from the boiler to an outside drain. The blockage is most likely at the most exposed section, such as a bend or the end of the pipe.
- Apply warmth by slowly pouring warm water over the frozen section or holding a hot water bottle against it. Do not use boiling water it can crack the pipe.
- Repeat as needed until water starts draining freely, confirming the ice has cleared.
- Reset the boiler following your manual's instructions. It should then restart normally.
