Thanks but no, more curious as don't recall it being done when British gas fitted new boiler 2011 and It was in the quote. Only one is the condensing pipe goes in to the down feed pipe of the washing machine and the annual inspection sheets say it should be put on the outflow side of the trap. I have no problems where it is. Look out for my new post with picture if I can work out how to add one its titled 'plumbers training school'. that's what it looks like in our airing cupboard.