The 21 KW, water heater is configured for cold climates where the incoming water temperature can drop below 55° F. The Model 220-3 is well suited for homes in the northern U.S. and Canada, and those in the southern U.S. that have large Roman-style or Jacuzzi tubs and that have generally more demanding water usage needs.

This water heater is configured for climates where incoming water temperatures are in the 50° - 60° F range. The Model 180-2 is suitable as a whole house water heater in the southern half of the U.S. and under certain conditions in northern climates; for example, a seasonal cottage.

This model is designed for moderate climates where the coldest incoming water temperature is 60° F or greater. As a whole house model, the 165-2 is best suited to homes in the southernmost regions of the U.S. (i.e. Southern California, Texas, Florida, etc.), as well as Mexico, and the Caribbean.

Model 145-2 is ideal for secondary point of use (single sink or low flow shower) application in any climate.

The Model 110-2 is ideal for secondary point of use application in warmer climates or in northern climates in the summer months.