I had a contractor install a Rheem electric tankless water heater in my casita. I initially wanted a much larger one but he talked me into the Rheem 13 KW 2.54 GPM. When the unit was installed the water was luke warm at best. The only way to get the water hot was to turn the ball valve down but then the pressure was too low. He then installed the 18kw Rheem3.51 GPM tankless heater and had the same problem.
I called Rheem today and they mentioned that an inline water regulator could solve the problem. The contractor did not seem to think so though. Honestly, I'm starting to question if this guy knows what he's talking about and would like some advice from someone who has experience with these types of water heaters. Do you think the water pressure is the problem and will an inline water regulator likely fix the problem?
I live in Santa Fe New Mexico so the ground water is probably in the 40's?
Any thoughts would be greatly appreciated.