Is it true that a 50 gallon water heater would be more efficient than a 40 gallon unit since it would cycle on fewer times during the day?
No. In fact the Federal Standard for minimum efficiency is lower for a 50 gallon than a 40 gallon water heater. Neither the storage capacity of a water heater nor frequency of energy input determines the efficiency of a water heater. Water heater efficiency all comes down to two measures of performance: Energy Factor and the 1st Hour Rating. The Energy Factor (.ef) is a measure of the overall efficiency rating of the water heater. It takes into account the heat loss of the shell, plumbing connections, central vent losses and additional variables. The 1st Hour Rating is a measure of the water heater’s ability to provide hot water in the first hour of operation. It is a combination of how much water is stored and how quickly the heater can heat water to the desired temperature. This is the measure to use in correctly sizing the water heater to meet your needs. Although the capacity of a water heater is an important consideration, the 1st Hour Rating is far more important. Your water heat
