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Green Collar Careers - Water Heaters

About half of the water heaters in America are electric.  That tends to skew the numbers a bit from Chart 202 as the report was generated using all forms of water heating.  In effect homes with electric water heat, the proportion of electricity used is doubled.  Another way to put it is if the home has electric water heat it will be closer to 18% of the power bill.

Typically natural gas will cost less then half of what electricity costs to heat water. Propane cost is dependent on volatile oil prices and may not offer any advantages. Solar water heating has the lowest operating cost with the highest new system cost.

When a builder installs a water heater in a new home they will choose the least expensive model unless the buyer has specified a particular model. Most homeowners will wait until a water heater fails or worse until they begin to leak before replacing them. Chances are the homeowner will not be willing to upgrade the water heater but in case they are the best option for electric is to select a tankless on-demand system.

Most homeowners never bother to adjust the water temperature on their water heaters and builders will typically set the temperature to about 160°. Every 10° reduction will save about 4% energy cost on a tank type water heater. The only thing in most households that needs water to be above 120° is a dishwasher that unusually operates at about 135°. Most dishwashers have pre-heaters so 120° is really an ideal setting. Resetting the water heater to 120° (usually about mid way on the thermostat) can reduce power required by the water heater by 16%. From chart 1 above we see that water heating accounts for an average of 9% of the average total consumption, and recall that only half the water heaters are electric.

For a home with electric water heat double the 9%. Multiply 18% * 16% for a net of about 3% savings on electricity.

Copper is a great heat conductor and most homes are plumbed with copper.  Be sure the exposed hot water pipes are wrapped with an insulating jacket.  Its not a major savings but enough that an 8 foot jacket section will pay for itself over just a few months.

Water Tank insulation blankets are helpful but often take a year or more to pay for themselves.

Homes that have long runs from the hot water tank to the kitchen sink may benefit from an under-sink tankless water heater.  Every second it takes to deliver hot water to a tap with a typical 2 gallon per minute wastes about 6 Watt Hours of electricity.  Say it takes 60 seconds to get hot water and hot water is drawn 3 times a day:

(6Wh * 60 seconds * 3 times per day * 365 days per year) / 1000 = 394 kWh

At 12¢ a kWh, that costs $47 a year.  An under-sink mini tankless water heater system (plug in 110 VAC) runs about $200 so the payback is about 5 years.

To learn more about reducing electricity consumption with electric water heaters use the search tool below to look up efficient water heaters electric.