Your a star 0. I could only find a copy for England (which looks very similar - maybe EU standards?)
The first one is it.
For anyone buying a new house, I highly recommend you bookmarking these regs. You can quote the relevant sections to your foreman if you have a dispute.
Go into the Publications List section of the DOE site, then click on http://www.environ.ie/DOEI/DOEIPub.nsf/wvNavView/PublicationsList?OpenDocument&Lang=en#09A433EBC36BB3CE80256B76005DADCE (Development and Planning Division) and after that click on the various Technical Guidance Documents of the Building Regulations, eg, http://www.environ.ie/DOEI/doeipub.nsf/0/09a433ebc36bb3ce80256b76005dadce/$FILE/Part%20D%20Tech%20Guide.pdf (Document D Materials and Workmanship).
Can anybody point me in the right direction, I'm looking for specific regulations relating to the installtion of open vented header tanks on heating systems. Great links on this thread but can't seem to pinpoint the one I'm looking for.