They send what is supposedly a licensed union plumber who should know what he’s doing. He installs a new hot water heater and vents it only to the chimney, not to the liner in the chimney. That’s mistake #1. Plus the flue slope is incorrect and can lead to gases not exiting properly(mistake #2). I’ll throw both these into Mistake #3: He told me he cannot see well.(Thanks for sendinig over a plumber with vision issues, that instills confidence!). And, rather than putting his tools down on the painted basement floor, he drops them, which left a number of scratch marks on the floor. Will never call them again. Their hold music should be «Send in the Clowns».