How to Size an Electric Water Heater

If everyone showers in the morning, you'll need a bigger water heater.

Residential water heater tanks range in size from 20 gallons to 120 gallons. On average, a water heater lasts 13 years, according to HomeTips. The more efficiently a water heater operates, the more energy you save. When choosing a tank, consider the first-hour rating (FHR) number. It represents how many gallons of hot water the heater supplies per hour during peak usage times. Consider the amount of hot water you and your family use to determine the size of water heater you need for your home.

Instructions

1. Note when you use the most hot water during the day. Determine your peak-time usage by answering some questions. Do all your family members take showers in the mornings or the evenings? What time of day do you wash dishes and do laundry? Do you do all the laundry on one day, or throughout the week? How often to you run the dishwasher, and what time do you start it?

2. Count the number of people in your home. Determine what water-using activity each family member normally does during your family's peak hot-water usage time.

3. Write down how many showers are taken during your peak-time usage. According to the U.S. Department of Energy, the average shower uses 12 gallons of hot water. For example, if three people in your home take showers during your peak time, your hot water usage equals 36 gallons.

4. Make a note of what other activities use hot water during the same peak-time hour, and total up the water use. For instance, if one person in your home shaves, another washes her hair, two people wash their face and hands and one meal is prepared during your peak hour, you use an additional 19 gallons of hot water. The federal government's Energy Savers website provides a list of typical household activities and the average water use for each to help you figure your hot-water needs.

5. Add up the gallons of hot water you use during your peak hour to determine the suggested water heater tank size. For example, if your family's hot water use during the peak hour totals 45 gallons, consider purchasing a 50- to 60-gallon electric water heater.

References

• Energy Savers: Sizing Storage and Heat Pump (With Tank) Water Heaters
• HomeTips: Storage Water Heater Buying Guide