I called John after finding him on the internet to fix my boiler. John came quickly, which was great since I did not have any hot water. However, he told me right away that there was a major problem with my installation and that he would have to reinstall everything to fix the problem, which would be expensive and would require a lot of time. I asked him to at least do a quick fix so I could have some hot water, which he did, then charged me for 2 hours after spending less than 1h30m for a service that he could have had completed in 30 min. Because of this red flag, I called another technician who came and said that my installation was just fine. Based on this experience and the comment from another user, it seems like he really likes to overstate problems. Beware!