We had a tankless Rennai hot water heater installed on an exterior wall of the house about two years ago. The unit is located diagonally opposite to where the original tank hot water heater was in the garage. Apparently, due to the length of run the hot water has to travel, we now have luke warm water to use for showers, kitchen and laundry. Even though the temperature is set to 125 degrees F we still have to run excess water to get it hot enough to use. We are looking for solutions to improve the situation.