What size water heater do you need?

To size a water heater for a house, a homeowner needs to know how many people live in the home and the family's hot water usage patterns. Average household usage for a family of four requires a 40-gallon hot water heater.

In addition to the household usage, a homeowner must decide whether he wants to use gas or electric heat, and he must also decide whether he prefers a tankless system or one with a tank. Rather than measuring capacity in gallons, tankless water heaters measure capacity by how much water can be heated and discharged at the specified temperature. If a homeowner is considering a tankless water heater, he should consult with a plumber as well as an electrician; tankless water heaters require additional electrical work during installation.