volume 66 - issue 1 - january 2016
Ways to save with water heaters
The water heater is the second-largest energy user in most homes. In an average home, water heating accounts for about 25 percent of your total energy usage—adding up to $400 to $600 per year to utility bills. Taking steps to reduce water-heating costs can save you money.
How does a water heater work?
The most popular method of water heating is the conventional storage tank. Storage water heaters hold between 20 and 80 gallons. When you turn on the hot water faucet, hot water is pulled out of the top of the water heater and cold water flows into the bottom to replace it. The water in the tank is heated by an electric resistance heating element, gas, solar, or oil.
The most important energy-related feature of storage water heaters is the amount of tank insulation. The more energy-efficient models on the market today have an R-value of at least 20. (The higher the R-value the better the insulator.)
Another type of water heater is called tankless, or on-demand. It uses electricity, propane, or natural gas to heat the water. The main difference between a tankless and a conventional storage heater is that the on-demand water heaters have no storage capacity. The water is heated as needed, which can save energy, but their flow rates are limited. Typical electric tankless systems have flow rates of two to five gallons per minute. This means that the supply of hot water may not meet demand depending on household needs. With an on-demand water heater, you may not have an adequate supply of hot water if you are doing a load of laundry while someone is in the shower. If there are more than two people in the household, this option is not the most efficient. Another thing to keep in mind if you are considering an on-demand water heater is that, in cold climates, they can actually use more electricity than traditional tank systems.
The recommended option for energy efficiency to fulfill your water heating needs is a heat pump (hybrid) water heater. Heat pump water heaters use electricity to move heat from one place to another instead of generating heat directly. For this reason, they can be two to three times more energy efficient than conventional electric resistance water heaters. To move the heat, heat pumps work like a refrigerator in reverse.
While a refrigerator pulls heat from inside a box and dumps it into the surrounding room, a stand-alone air-source heat pump water heater pulls heat from the surrounding air and dumps it—at a higher temperature—into a tank to heat water.
Understanding the type of water heater you have and how it works can help you determine the best ways to save energy and save money.
Ways to reduce your water heating costs
The number of people in your household, the amount of laundry you do, and your dishwashing habits have an impact on your hot water usage.
1. Lower the water heater temperature. Water heated to between 120° and 125° is hot enough for most households. This is about midway between the "low" and "medium" settings on most water heaters. If you do not have a dishwasher or if you have one without a booster heater, keep the water temperature at the medium setting.
2. Conserve water. Water-conserving or low-flow shower heads can cut hot water use in half. Limiting showers to five minutes could also reduce hot water use.
3. Insulate your water heater. An insulating jacket may pay for itself through energy savings in less than a year. The older the water heater, the greater the potential savings. Always follow the manufacturer’s instructions given in your owner’s manual. (Water heater jackets are not recommended for all models.)
4. Install a timer. A simple timer that shuts the water heater off 12 hours a day will pay for itself in less than a year. Savings are greater for water heaters located in unheated garages and basements.
5. Use energy efficient appliances. Purchase ENERGY STAR® clothes washers and dishwashers to conserve water and reduce costs.