The tap in the hot-press is permanently open and the pressure remains steady at 1 bar. I've had absolutely no problems except to bleed the system -
The reason it remains at 1 bar (it must change between heating off and on) is that there is a non return valve before that valve which stops water from your heating system going backwards into the public supply so your pressure will stay at whatever the supply to the house is and in Ireland that is usually not more than 1 bar. You really should close the inlet valve and see how things go.
Good place to help identify fittings
http://www.sanbrafyffe.ie/products.html or www.rwc.co.uk
bottom of this page to see non-return valve which is usually brass [broken link removed]