How can I ensure my gas appliances are the highest possible quality?

When buying a gas appliance, deal with a reputable outlet and check that the appliance carries the CE mark. (Confirmation that the Appliance is suitable for use in Ireland). Your installer should be competent and issue you with a 'Conformance Declaration' for the new appliance installed. Keep the declaration certificate in a safe place. 

Every new appliance is supplied with a full instruction book, essential to the correct and safe use of the appliance. Read it carefully and get to know your appliance. Keep the instructions handy. If you are moving house leave the instruction book for any appliance you are not taking with you.