I am planning to replace my hot water tank with a Noritz NRC98-DV tankless hot water heater. The best location to mount the new heater is in the basement on an outside concrete wall. The heater will be at a height that puts it half above grade and half below. The climate here includes severe winter weather.
The instructions with the heater assume I'm mounting it via screws to a wooden wall (e.g. "...be sure to hit a stud..."). Rather than building a full wall with studs, it would be more convenient for me to mount either directly to the concrete wall or perhaps to, say, a piece of plywood that is mounted directly to the concrete wall.
Will the plywood method or the direct mount method work for me? Is one or the other preferred? Are there moisture/condensation considerations with either method? Are masonry screws (e.g. Tapcons) the preferred method for attaching?