PRESSURE ON BAXI COMBI KEEPS INCREASING???????????

Hi

My Baxi Combi 105e is slowly increasing pressure? I have recently had the sysyem drained so new pipework can be fitted because I wanted to re-site/ extend 2 rads. Since this work the pressure was set at 1.4 bar when cold but has now increased to 2.2?? I have bled each rad when cold .Recently I removed 2 rads when I was redecorating and noticed when they were hung back and the return/relief valves open (also the bleed valve open to fill and shut when full) the pressure came back to 1.4 bar. However today it has crept back up to 2.2bar. I am sure the filling loop is not open but I am not sure about the pipe with the screw head on it??

Any help is greatly appreciated!!