Hi Adamson,
Southern Ireland and their acceptance of qualifications from other EU member States is not as straightforward as it should be.
As a minimum ( for the domestic qualification) you need to demonstrate:
NVQ Level 3
Gas Safe Registration
Work Experience CV / Schedule since you completed your NVQ Level 3 or for 10 years which ever is shorter.
Normally that is sufficient for you to achieve acceptance to be granted RGI for Gas in Southern Ireland.
The heart of the issue is that in Ireland there is an Irish qualification at NVQ Level 3 in Gas Fitting as well as a separate NVQ Level 3 in Plumbing. Their equivalent ( for gas) is an NFQ ( their terminology) Level 6 in Gas Fitting. There is no obvious parallel vocational UK qualification in Gas Fitting that is comparable. Consequently (sometimes) the perception is that an NVQ Level 3 is below an NFQ Level 6. Electrical trades have the same the same issue.
They are also acutely aware that it is possible to be Gas Safe Registered in the UK without holding an NVQ at any level. Without an NVQ to transfer a Gas Safe Registration for use in Southern Ireland you would have to start from scratch ( this obviously does not apply to you).
If after satisfying the above criteria they still may ask you to take the “renewal Domestic Gas Installers” - DGI - RGI course ( 2 days) - not particularly onerous, but you need to know the detail of the local Regulations ( the reference number of which is IS 814) - but it has a strong emphasis on LPG.
I don’t have experience in placing UK Commercially Registered Gas people into Ireland, but I do know that the Trades Union involvement in that sector ( in the Dublin area) is at a much higher and more organised level that it is for the equivalent sector in the UK. The majority of Irish commercially registered gas sector engineers are former ESBi people.