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Energy-Efficient Water Heaters | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Styles of Water Heaters Fuels for Water Heaters Purchase and Operating Cost of Selected Types of Water Heaters Other Factors that Effect Energy Use
Here we emphasize the factors that impact the efficiency of the water heating system. These include style, fuel, age, and energy saving options. Styles of Water Heaters Hot water storage systems use energy to heat the hot water, and then to maintain the temperature while heat is lost through the walls of the tank. Accordingly, the larger the tank, the more energy lost, so you want to make sure you do not install an oversized unit.
While most water heater systems are stand-alone systems, they can also be integrated with the boiler used to heat the home. (It is also possible to integrate water heating with a hot air furnace, but such installations are very rare). There are two styles of integrated systems; Tankless Coil and Indirect. Tankless Coil systems heat water as it is needed just as a demand system, the only difference being that the boiler is used to heat the water. Indirect systems also heat water in the boiler, but the water is then stored in a tank. The advantage of a tankless coil system is the avoided cost of purchasing a separate water heating system. The disadvantage is that during the non-heating season water heating is inefficient since the heating system must operate solely for heating water. Indirect systems have the added cost of a tank, but the improved efficiency generally offsets this cost; in fact, these may be the most efficient systems available today. Tankless coil and indirect systems are more common with older oil boilers, but they are also installed with gas boilers. Fuels for Water Heaters If you are considering replacing your Water Heater check out PSE’s Contractor Referral Service and get connected with a pre-screened, independent Heating/Cooling contractor. These contractors provide a free, no-obligation bid. If you plan to install a High Efficiency Gas Water Heater with an Energy Factor of 0.62 or higher, PSE has a $40 rebate available. Email Us for more energy efficiency information or to speak with an Energy Advisor call, 1-800-562-1482. Electric water heaters are the next most common type, accounting for about 38% of all installations, including heat pump water heaters, which have a very small market share. Electric water heaters (except heat pumps) are generally the most costly to operate. Although the non heat pump electric water heaters are the least efficient systems available, they have improved in efficiency by almost 10% in the last 25 years. Oil water heaters comprise only 4% of the market, the remaining systems being either propane or solar. Oil systems have become less popular over the past several years with the increased availability of gas and the introduction of heat pump systems. Oil systems are considerably more expensive than gas to install. In addition, they tend to last 8 years on average, versus 13 years for a gas or electric system. Solar heating was popular during the years that subsidies were widely available, but its popularity decreased when those subsidies dried up. In recent years, solar heating for hot water has made a comeback. It is expensive to install and will typically require a small back up system. However, a solar system is so economical to operate that it becomes cost-effective over its lifetime. The following exhibit indicates the average purchase and energy cost of different types of water heaters using average prices of 10 cents per kilowatt-hour of electricity, 60 cents per therm of gas, and 90 cents per gallon of oil. Purchase and Operating Cost of Selected Types of Water Heaters (Source: American Council for an Energy Efficient Economy)
Other Factors That Effect Energy Use
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