The only reason for the 4 stars on expertise is the he was working on a old precision Temp unit. Chuck went beyond the call to get this crazy system working - including a call back on a Sunday and ordering special anti-freeze for this boiler. HE stayed with it until we had hot water once again when I was ready to replace the entire unit. He could have made a lot more money off of the situation but instead fixed the old one MANY thanks. He was recommended by Ron's Osbourne's RV repair.