Check that the gas line to the heater is adequate, and that you can install the larger flue required by the heater. Also, if you install it yourself, have an inspector show you how and where where to install the pressure/temperature relief valve for proper safety. And do not use the pressure only valve supplied with the heater.: we recenty saw a home show that included the installation of a tankless water heater. my husband and i are very interested in having one installed in our home, as we have very heavy lime amounts in our water, and our electric tank needs the elements changed 3 times a year, and usually while i am taking a shower! we have had the aquastar recommended to us, but after seeing a comparision of their units, believe the 170 would be better for us then the 125. would like to know where we can purchase one of these tankless units, or if anyone has any other companies or models they would recommend i would appreciate it. the gas dealer told us the price for the 125 would be 820 dollars. can we purchase it for less? : we will be running this water heater off of propane, not natural gas…thanks for your help…sherry vogt