If it is low pressure, you need to increase the pressure, should read about 1 bar when the system is cold. Not dangerous, but very surprised your system is still working, most cut out. Somewhere close to the boiler, will be a fill loop. A flexible metal braid pipe, with a valve on it. as long as both ends of that pipe are connected, open the valve to fill boiler. VERY slowly. increase pressure to 1 bar, or if no dial, until light goes out. IF the pressure drops again in a short period of time, you have a leak on the system, and need to get that seen to. You have not given the make or model number, which would of helped me.
SD, April 2012
