Installed tankless water heater connected to natural gas line. Following installation, we smelled gas on several occasions. At first, he said that was just residual from the install. Came back once and said that he didn't smell gas, he smelled something else. I asked him to use his gas sniffer, but his was not working and that he would have to order a battery for it. (Who works on gas lines without a gas sniffer?). Frank was adamant that the plumbing was fine and that the problem might be with the water heater itself. Called Rinnai and they said the water heater is sealed and that the only possibility for a leak is in the connection to the plumbing. Called Frank back but didn't hear from him for a while, so I bought a natural gas alarm and it went off. Called Frank back. He came with a new sniffer, and found the leak in a joint in the wall that was not tightened enough. Had to cut the wall out to get to it. He repaired it but the whole process took a few months, left us with a potentially dangerous situation, and delayed install of cabinets under the heater. Won't use Elite Plumbing again.