What Size Water Heater Do You Need?

One of the great things about living in the 21st century is the ability to have hot water at your fingertips. With a twist of a handle, your hot water heater churns out what you need to wash your dishes or take a shower. But if your heater goes bad or you're upgrading, you're probably wondering what size heater you need. The answer depends on what type of water heater you're looking at: a storage water heater or a tankless on-demand heater.

Regardless of what type of water heater you're getting, the size you need hinges on how much hot water you and your family will use at the busiest time of the day. For a water heater with a tank, this figure is called the First Hour Rating, or FHR. This is the total amount of hot water that your household uses at peak. A good rule of thumb is 12 gallons of hot water per person. So if you have five people in your household, you know you need 60 gallons of hot water.

Water Heaters with Tanks

Following the example above, you don't actually want one with a 60-gallon capacity. That's because, when you start using hot water, cold water enters the tank. This temperature drop tells the heater to start up. The amount of time it takes to heat the tank of water back up is called recovery time. The FHR rating for a hot water heater takes all of this into account, giving 40- or 50-gallon water heaters an FHR of 70 or higher.

Going Tankless

For tankless water heaters, figuring out the demand is based not on overall volume, but on the flow rate. For instance, if at peak usage, you'll have two showers running and the kitchen sink in use, your flow rate is going to be about 5 gallons per minute (GPM). The heater then has to be able to heat the water to 120 degrees Fahrenheit. According to the US Department of Energy, the average inlet temperature for water is 50 degrees. So in this case, you want one that will handle at least 5 GPM with a 70 degree increase in temperature.

Getting a new water heater is a terrific decision that doesn't only improve the value of your home; it will save you money in the long run. Finding the right size for your home is easy as long as you remember to calculate the volume of water you need for a tank water heater or the flow that you need for a tankless heater. Contact a company like R Acres Plumbing Company LLC to get started.


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