Hello Gentlemen I am looking for a little advice. I am looking to have a Megaflo Unvented Direct Hot water cylinder installed. I understand that this needs to be installed by a plumber with a current G3 qualification. So here's what I need a little help with: 1 Apart from taking a plumbers word, how do I know that a plumber has a current G3 qualification? 2 What is current for a G3 qualification; 1 year, 2 year, 3 year......more? 3 Should I recieve my G3 certificate on the day of instalation, ie is this a certificate that the plumber can write out and issue on the spot?