combi boiler work on preasure systerm ,preasure vessel need air that is why its not stable,can be pump air with bicycle pump to 1.5pl
lal, June 2011
No it is not safe at 4 bar.If you are finding that the pressure is always increasing and you are always releasing water to lower the pressure then the problem is at your quick fill point.
If the valve from your cold water pipe which fills up the heating system is not fully closed then water will gradually pass into the system slowly increasing the pressure.
