Selecting a water heater involves determining a few things about the heater and a few more things about your family’s water usage.

They’re all important, because water heating accounts for as much as 25 percent of your total energy consumption. The average service life of a water heater is 10 to 13 years, so you’ll be living with your choice for some time.

When you start looking for a replacement, you’ll find that it’s almost impossible to buy a model that’s the same as the one you have now, even if you choose the same manufacturer. That’s because water heaters have become much more efficient since your tank was purchased. New models use less energy and heat more effectively. Here are some guidelines for selecting a water heater that meets your needs.

First, determine your household demand for hot water during the daily peak hour of usage. Here are some average peak amounts of hot-water usage in gallons:

•    Five-minute shower: 10 gallons.
•    Shaving and brushing teeth and other hygiene habits: 2 gallons.

Calculate your total demand per hour by multiplying each of these activities by the number of people using water during the hour of peak demand. For example, if three people shower every morning, the total for that activity is 10 gallons x 3, or 30 gallons.

Add to the above totals any fixed water demands occurring during the peak hour. These include:

Cooking: 4 gallons.
Running the dishwasher: 6 gallons.
Doing the laundry: 7 gallons.

The cumulative total of all the above demands is the peak hourly demand in gallons, which should be compared to the first-hour rating shown on the yellow EnergyGuide label of a new water heater.

The first-hour rating expresses the gallons of hot water a heater can deliver in an hour of peak demand. A water heater with a first-hour rating that’s slightly above your peak hourly demand will provide some margin for increased demand if your household expands.

While you’re probably leaning toward another tank-style water heater, you may want to use this as an opportunity to consider alternatives, as well. Solar and heat-pump water heaters are available, as are highly efficient tankless systems. Instead of storing water, a tankless system delivers hot water only as needed. Because there’s no standby energy loss, a tankless system can save you considerable energy dollars. The Department of Energy estimates that a tankless system can be 20 to 30 percent more efficient than a conventional storage water heater.

Apollo Home Heating, Cooling & Plumbing has served Cincinnati homeowners since 1910 with trusted sales and service expertise. Call us for more advice about selecting a water heater for your home.

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