Heating water accounts for approximately 15 to 25 percent of a home’s energy use. With a high efficiency water heater, homeowners can save money on energy bills because it uses use 10 to 50 percent less energy than a standard water heater model. The energy savings from high efficiency water heaters depend on family size, water heater location, and the size and placement of water pipes.
Types of High Efficiency Water Heaters
- Storage (Tank) Water Heaters: Water is kept hot and ready for use at all times in insulated storage tanks with capacities ranging from 20 to 80 gallons. Many fuel options are available, including electricity, natural gas, oil, and propane. One drawback of these units is the energy used (wasted) to keep the water hot at all times, otherwise known as “standby losses.”
- Demand (Tankless) Water Heaters: Water circulated through a large coil is heated only on demand using gas or electricity; there is no storage tank continuously maintaining hot water. A possible concern with this technology is the limitation on the number of fixtures that can simultaneously use hot water. However, there is an endless supply of hot water and standby losses are eliminated.
- Heat Pump Water Heaters: Heat pumps transfer energy from the surrounding air to water in a storage tank. These water heaters are much more efficient than electric resistance water heaters and most effective in warm climates with long cooling seasons.
- Solar Water Heating: While the initial purchase price of solar water heaters is very high compared to standard models, they can be cost effective. That is because the sun’s energy is harnessed to reduce operating costs up to 90 percent. Solar water heating systems require a conventional water heater as a backup water heating source to ensure hot water is available when solar energy is not.
The following are important water heater metrics to consider:
- First-Hour Rating (FHR). FHR measures how much hot water will be available during the busiest hour of the day. A large tank does not necessarily translate to a higher FHR. The recovery rating is important as it indicates the water heater’s ability to replenish hot water as it is drawn from the tank.
- Efficiency. The water heater’s efficiency is measured as an Energy Factor (EF), which is usually listed beside the EnergyGuide label. The higher the number, the more energy efficient the water heater.
Source: ENERGY STAR
