Choose the right water heater

Heating water is a significant portion of our annual energy usage. This also makes it a common focus for those who hope to reduce their energy consumption and monthly bills.

The average American household uses 15 million BTUs to heat water every year. Water heating consumes about 15 percent of the electricity and 25 percent of the natural gas and propane used in homes.

Storage water heaters are the most common kind of water heater in American homes. These are made up of a tank of 40 to 60 gallons surrounded by two or three inches of insulation. Electric resistance heat or a flame is used to heat the water, which remains hot and ready for use.

Electric water heaters:

Electric storage water heaters are all extremely efficient, with the best only about five percent more efficient than the worst. Almost 100 percent of the electricity consumed heats the water for the family’s use.

Many people think that it costs a lot of money to keep all that water hot all the time, but the insulation keeps nearly all the heat in the water.

A good quality, 95 percent efficient electric water heater (frequently referred to as an Energy Factor of .95) with heat traps and insulated pipes will lose only about $23 worth of heat every year. Less than $2 every month.

That’s not bad, considering the total annual cost of water heating is about $500.

Less than that, actually.

At Heartland’s general rate of 9.35 cents per kilowatt hour, that 95 percent efficient electric water heater will use $441.85 in electricity.

With numbers like that, a 10 minute shower (using a 2.5 gallon-per-minute showerhead) will cost about 24 cents. A bit more if you like your shower extremely hot.

Combustion water heaters:

Propane and natural gas water heaters are considerably less efficient than electric water heaters because about 30 percent of the heat generated goes up the flue instead of into the water. The need for ventilation also makes it harder to insulate propane and gas water heaters.

Typical propane and natural gas water heaters are 59 percent efficient. If propane is $2 per gallon, it will cost $555.10 to heat an average family’s water. In fact, propane prices need to be less than $1.60 per gallon to cost less than electricity at Heartland REC’s current general rate of 9.35 cents per kWh.

Natural gas is considerably cheaper, however. At a price of $10 per thousand cubic feet, it will cost $246.83 to heat that year’s worth of water. Unfortunately, natural gas isn’t an option for most Heartland REC members.

Those considering propane or natural gas do have a couple things they need to keep in mind.

First, recovery time for propane and gas water heaters is shorter because they produce more heat. When all the hot water is used, gas water heaters can heat the cold water quickly. This can be important to large families with undersized water heaters.

However, combustion water heaters do need to be properly vented. Their simple combusion system can become a safety problem if the burner produces carbon monoxide and the chimney backdrafts - a common occurrence. Testing draft and carbon monoxide should be part of installation and maintenance of all combustion water heaters and also whenever weatherization, heating and air-conditioning work is done.

Tankless:

Tankless water heaters are currently getting a lot of attention.

They provide a continuous flow of hot water, but only at a limited rate. High-end tankless gas water heaters can be much more efficient than their inefficient storage counterparts. However, electric tankless water heaters save very little compared to 95 percent efficient electric storage water heaters. Additionally, because of their very large power draw, (up to 20kW) electric tankless water heaters can be a problem for utilities and for homes without robust wiring.

Other Options:

Heat pumps can also be used to provide a home’s hot water. These can be several times more efficient than standard electric water heaters.

Solar water heaters can also be used to heat water. Designs and results of solar water heaters can vary greatly, but can provide substantial savings.

Rebates:

Heartland Rural Electric Cooperative offers rebates to members who install new energy-efficient electric storage water heaters.

Electric water heaters of between 40 and 60 gallons must have a minimum .93 energy factor. (That means they must be at least 93 percent efficient. A 95 percent efficient water heater would have an energy factor of .95, which is even better.)

Electric water heaters of 60 gallons or greater must have a minimum energy factor of .91.

The rebate amount for all non-lifetime warranty water heaters is $200. Water heaters with a lifetime warranty qualify for a rebate of $300.

Qualifying 40-gallon

Water Heaters:

GE SmartWater electric water heaters with an energy factor of .94 are available at Home Depot. (Model SE40M12TAH)

Kenmore Power Miser 12 electric water heaters with an energy factor of .95 are available at Sears. (Model 32144)

Whirlpool Energy Smart water heaters with an energy factor of .95 are available at Lowes. (Model EE3J40RD045V)

Local plumbing contractors may have access to additional brands of energy efficient electric water heaters. These include the Rheem Imperial Energy Miser products, and the AO Smith brand Conservationist and ProMax Plus models.

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