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Tips for Sizing a New Water Heater

Tips for Sizing a New Water Heater

2nd Nov 2020

A properly sized water heater will meet your household or business hot water needs while operating more efficiently. It will also help keep your utilities bills under control. Thus, the selection of a water heater takes a bit of forethought. If a new water heater is in your future, take some time to figure how to size it to fit your needs. These pro tips will walk you through the process.

To properly size a storage water heater for your home you should use the heater’s first hour rating (FHR). This figure reflects the appliance’s efficiency (how quickly the water heater can reheat the water) and gives an idea of what it can handle at a peak hour of usage.

The numbers below can help you get a general idea of peak hour usage and determine the ideal FHR.

  • Bathing or showering (per person)—20 gallons
  • Washing hair (per person)—6 gallons
  • Washing hands (per person)—2 gallons
  • Washing dishes by hand—6 gallons
  • Shaving—3 gallons
  • Running dishwasher—14 gallons
  • Running clothes washer—30 gallons

Another way to determine how much hot water you will need and therefore what size heater you may be in the market for is to use this rough estimate based on the number of people who will be using the heater.

For 1 to 2 people: 30-40 gallons

For 2 to 3 people: 40-50 gallons

For 3 to 4 people: 50-60 gallons

For 5+ people: 60-80 gallons

Another factor that will help you determine what size water heater you may need is to know which hour during a typical day is your busiest “hot-water-using-hour”. For most people these times include the morning as people are showering, preparing breakfast, etc. For others it can be during the evening as people are washing clothes, preparing dinner, etc. Of course for businesses that highly rely on hot water nearly all the time – such as restaurants, Laundromats, etc. the need will be greater. For these kinds of businesses we have a 100 gallon gas water heater for commercial use.


Smart business owners are constantly thinking of ways to cut operational costs and the way to do this is to choose the right commercial hot water heater for your business. So, take the time out and carefully go over these criteria before making your selection. We are sure you will conclude that our gas water heaters are just what your business needs.