Hi guys, I'm working sub contract for a plumbing company installing Air source heat pumps, they have there MCS audit coming up and have asked if im 18th edition, when I done my exams it was 15th edition, I've done 15th, 16th and 17th but never got round to actually doing the 18th, so my question is do I need 18th to subcontract to a heating company that has MCS accreditation thanks in advance