I have a potterton boiler. A red light is flashing saying 0.4 bar which I assume means low pressure. How do I raise the pressure? I know I have to open some valves somewhere but I'm not sure what these valves look like and where they are. There are no leaks anywhere I have checked.
Somewhere nearby, perhaps below the boiler, there'll be a bit of flexible hose that loops between two of the copper pipes. On this flexible hose, there'll be an isolation valve. It might have a plastic tap on it, or it might just look like a screwhead, and you turn it with a screwdriver. There might even be one each end of the flexible hose, but usually there's just one. Open the valve, you'll hear water rushing through. When the sound stops, close the valve again. It's important to close it again, as this isolates your central heating water from the mains supply. This should raise the water pressure in the central heating system.
