30 Jan

How to Determine the Right Size Water Heater for Your Home

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What do water heaters and shoes have in common? They both really need to be the right size to work and best suit your needs.

When choosing the correct water heater size, bigger isn’t always better, and smaller doesn’t equal smarter. To most precise method for determining the ideal water heater capacity is calculating the highest average number of gallons used, also known as “peak hour demand.” It’s also common to estimate usage based on the number of people in your household.

Water Heater Size

Calculating hot water usage

To determine how much hot water you require, it’s important to take a look at the hour(s) during which your water heater is most frequently used. For example, if most members of your household shower in the morning while dishes and laundry are also being washed, your water heater will need to be able to keep up with that demand.

In general, a small 30-gallon tank water heater is typically enough for one to two people, an 40- to 60-gallon tank is best for three to four people, and an 80-gallon tank is often required for over five people.

It is important to note that the size requirement of your water heater is dependent on hot water usage habits, such as how many appliances in your home are using hot water at any given moment.

If you want to take the guesswork out of finding the appropriate size water heater for your household needs, you can calculate the averages below to find the busiest usage hour, also known as “peak hour demand.” (Formula via the Federal Energy Management Program Energy Cost Calculator)

  • Shower: avg. 10 gallons
  • Shaving: avg. 2 gallons
  • Hand dishwashing/food prep: avg. 4 gallons
  • Dishwasher: avg. 6 gallons
  • Laundry: avg. 7 gallons

Combine these estimates to find the total number of gallons used during one hour. For example, if you have three members of your household taking a shower within one hour, your total gallons used for showering that morning would be 30 gallons. Add the usage for each activity, multiplied by the number of members performing said activities, to find your total usage requirements.

You can then use this total number to find the appropriate water heater size. When shopping for a new water heater, you will also want to check that the unit’s “first hour rating” falls within 1-2 gallons of your peak hour demand (the number you found above). These numbers will need to be as close as possible to ensure you have the hot water you need, when you need it.

Water heating advice in Fredericksburg, Stafford, and King George Counties

If calculating hot water usage sounds too complicated, or you would prefer to get an expert’s recommendation, contact Robert B. Payne, Inc. We can help you determine the perfect water heater size and model for your home. Send us a message or call (540) 373-5876 to schedule an appointment.