This Smart Technology electric tankless water heater is configured as a "whole home" model for climates where incoming water temperature is 62°F and above. The ECO 18 is capable of heating over 2.5 gallons per minute, which is the equivalent of one water saver shower head (with a 1.5 gpm flow) and one sink with a low inlet water temperature of 62°F, and an output setting of 105° F. Two showers emitting no more than 1.5 gpm each can be run simultaneously when incoming water temperature is above 70° F. Digital temperature control allows you to set your temperature in increments of 1°. All tankless water heaters are sized based on flow rate and temperature rise, and there is a direct relationship between the two. So if used in a cold area requiring a high temperature rise, it will be more limited in the amount of fixtures (gallons per minute) it can heat at one time compared to a warmer climate. However, when sized properly it will provide endless hot water and only consume the energy needed, giving the user complete control. Prior to purchase and installation please verify this model is the right size for the expected demand and electrical requirements. The ECO 18 requires a minimum 150 amp electrical panel for installation with (2) 40 amp double pole breakers connected to (2) sets of #8 awg wire. Plumbing connections are 3/4" NPT. For additional assistance please feel free to contact our support center at 877-474-6473.