Selecting a New Water Heater

Whether you’re replacing a worn-out existing water heater or looking for the best model for a new house you’re building, it pays to choose carefully. Look for a water heater that satisfies your hot water needs and uses as little energy as possible. Often you can substantially reduce your hot water needs through water conservation efforts.

• Think About a Replacement Now: If you're like most people, you’re unlikely to go out looking for a water heater until your existing one fails, leaving little time to look for a water heater that most appropriately fits your needs and offers the highest level of energy efficiency. A much better approach is to do some research now. Figure out what type of water heater you want—gas or electric, storage or demand, stand-alone or integrated with your heating system, etc. Then, figure out the proper size for your household.
• Sizing a Water Heater: The capacity of a water heater is an important consideration. The water heater should provide enough hot water at the busiest time of the day. The ability of a storage water heater to meet peak demands for hot water is indicated by its "first hour rating." This rating accounts for the effects of tank size and the speed by which cold water is heated. Demand water heaters should be sized according to the required gallons per minute (gpm) flow rate and temperature rise required for your largest expected hot water fixture (usually a shower).With solar water heaters, you should discuss your requirements carefully with the solar water heating salesperson. You will need to size both the solar hot water system itself and the back-up electric or gas water heater. It generally makes the most sense to size a solar water heater to provide two-thirds to three-fourths of your total demand, and provide the rest with a back-up system.
• Fuel Options: What type of fuel makes the most sense for your water heater? If you currently have an electric water heater and natural gas is available in your area, a switch might save you a lot of money. Oil- and propane-fired water heaters are also usually less expensive to operate than electric models. Before you rule out electricity, though, check with your utility company. It may offer special off-peak rates that make electricity a more attractive option.
• Look for Sealed Combustion or Power-Vented Systems: For safety as well as energy efficiency, look for gas- or oil-fired water heaters with sealed combustion or power venting. Sealed combustion means that outside air is brought in directly to the water heater and exhaust gases are vented directly outside. The combustion is totally separated from the house air. Power-vented equipment can use house air for combustion, but flue gases are vented to the outside with the aid of a fan. In very tight houses, drawing combustion air from the house and passively venting flue gases up the chimney can sometimes result in back-drafting of dangerous combustion gases into the house.

COMPARING THE TRUE COSTS OF WATER HEATERS

When comparing the cost of various water heating options, keep in mind that there are two types of cost you need to look at: purchase cost and operating cost. Life-cycle costs, which take into account both the initial costs and operating costs of different water heaters, provide a much more accurate representation of the true costs of the water heater than the purchase price alone. Life-cycle costs for the most common types of water heaters under typical operating conditions are shown in the table here. When both purchase and operating costs are taken into account, one of the least expensive systems to buy (conventional electric storage) is one of the most costly to operate over a 13-year period. An electric heat pump water heater, though expensive to purchase, has a much lower cost over the long term. A solar water heating system, which costs the most to buy, has the lowest yearly operating cost among electric systems.