Most of us take having hot water for granted. It’s always there and ready for our use. Whether we’re giving the kids a bath or doing laundry, hot water is an essential part of every day life. It’s not until the water heater fails that we realize how important the heater and the hot water it produces is.

Your water heater has a very specific job to perform and it must operate at a satisfactory level to accommodate your family’s needs. If your demands on your water heater have grown, it may be time to look for a more energy efficient unit which is able to better meet the demands of your family.

If you are like most, deciding what size of unit to buy can be difficult.

Some factors to consider are:

•How many family members?

•Of those, how many are children or teenagers?

•How many bathrooms do you have?

•Do you have a garden tub or hot tub?

•How many times per day / week do you run the dishwasher and clothes washer?

• What is your family’s Peak Hour Demand?

Peak Hour Demand is key when determining the size of water heater your family needs. Peak hour demand is the busiest one-hour usage period of the day. For example, does each family member shower in the evening? Is laundry done during this same time period? Is the dishwasher running also? If so, you may find that your Peak hour demand is in the evening. Another helpful tool to decide when your family uses the most hot water is the chart below:

After you have calculated your peak hour demand, you can use a make and model chart to choose the correct water heater within +/- 2 gallons capacity. When selecting the proper size, look for the "first hour rating" on the model chart. This is a function of the initial storage capacity plus the ability of the unit to heat while in use. In the example above, you would select a Rheem residential water heater with a 65 gallon storage capacity.

Now that you have a better idea of the size of unit best fits your family’s needs, how does your current water heater compare? It’s worth checking out - even if you’re not particularly considering purchasing a new unit.

The Energy Factor

The Energy Factor, implemented with the National Appliance Energy Conservation Act, is a relative number that is a standard measure for storage water heating products. It is determined through the Department of Energy (DOE) standard test procedure. This procedure involves a water heater that is put through a 24 hour simulated use test.

The same DOE simulated use test is used by all water heater manufacturers. All of the test procedures are mandated by the DOE and include:

•Length of Test

•Thermostat Setting

•Water Temperature of the Cold Water Delivered to the Water Heater

•Quantity of Hot Water Drawn from the Heater in 24 Hours of Testing

The final number is displayed in a decimal equivalent. It’s not meant to be a percentage. This number, called the Energy Factor (EF) represents the efficiency of the water heater. The higher the EF, the more efficient the unit.

The Energy Factor represents two major conditions when determining water heater efficiency:

•How efficiently the unit uses fuel (gas or electric)

•How efficiently the unit retains heat during "standby"

How Useful is the Energy Factor?

The EF aids the consumer by making comparison shopping easier. You can now compare the EF rating of several units. Remember when comparing, be sure to compare electric to electric, gas to gas and so on. Also, keep the same capacity water heater in mind when comparing. Comparing different fuel sources or capacities is likely to give you a false or misleading understanding to the actual savings and efficiency of the water heaters you’re considering.