Leaking Pressure Relief Valve?
These valves are designed too to let out excess pressure in the case of the boiler over-pressuring, usually when the boiler exceeds 3 bars.
Failed ‘PRV’ is something our engineers are faced with so often! If your boiler is losing pressure it can be a faulty pressure relief valve either inside the boiler or on the external pressure relief valve.
Like any components of a boiler, they can fail at any point and once they have been triggered there is a high chance that they will not seal back up. The water will usually leak very slowly and will often evaporate before any visible water can be noticed, but a good indication of the leak is rust or limescale stains around the pipework.
Although these leaks can be identified by leak detection engineers it is also a leak that can generally be identified by a qualified heating and plumbing engineer.