Number of reasons why it could be losing pressure.
1 A leak
2 Faultly expansion vessel
3 Faulty pressure relief valve
4 Faulty auto air release valve
5 Air being released trough the auto air vent.
Given that you have just added some radiators and bled the air out there is probably alot of air left in . The auto air vent will release this air slowly overa few days and as a result the pressure will drop.
Best course of action top up the system to around 2 bar and monitor it. If drops over the next couple of days top up again. It should settle down within a week if not some fault finding is in order.Hope this helps
No they're not typical to any boiler this new.
I would say that 2,3 & 4 are unlikely causes in a fairly recent installation.
A quick couple of tests will rule these out.
Check the pressure relief valve vent ( 15mm copper pipe to outside) for dripping. Should be dry.
With the gauge reading about 2 bar turn the c/h on max ( turn up any room stats etc to max)
Watch the gauge as the pump and burner kick in. The pressure should rise maybe a 1/4 of a bar then stay the same. If the pressure continues to rise as the boiler gets to heat it will finally get to 3/3.5 bar and the pressure relief valve will open and reduce the pressure.(this would indicate a vessel with no charge )
Find the auto air vent in the boiler it looks like this
Check the top around the cap isnt crusted and wet , the cap should be loose by a couple of turns.If yery wet and crusty this would indicate the float inside isnt operating and either clean or replace.
If none of the above I,m afraid you are looking for leaks.
Hope this helps