Efficiency Comparison Charts

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How efficient is propane over electric?

Electric water heaters are often considered to be close to 100 percent efficient. This is true at the point of use. However, if you consider the overall energy efficiency (from production of the electricity to the point of use), the result is much less. The overall system efficiency of an electric heating system-including the energy consumed to produce the electricity in the first place- is about 28.5 percent whereas the overall efficiency of a propane system is close to 93 percent. Therefore, a propane model with 75 percent combustion efficiency is actually more efficient than an electric model rated at 100 percent efficiency, illustrated in the table below.

Efficiency Comparisons Between Propane and Electric Water Heaters

Water Heater Input Recovery, G.P.H (90 degree rise)
50-Gallon Propane 40,000 Btu/hr 40.5
50-Gallon Electric 4500-watt 20.7

Recovery Factor

Propane water heaters can also recover much faster than electric water heaters. Without increasing the size of the water heater, a household’s hot water capacity can be doubled by simply switching from electric to gas. Recovery rates for two 50-gallon water heaters (propane and electric) are shown in the table below:

Model Price
Premier Plus 30 Gallon $322
Premier Plus 40 Gallon $322
Sears Kenmore 40 Gallon $339
Premier Plus 50 Gallon $375

Equipment Costs

There are always two types of costs to consider when purchasing a water heater (or any other major appliance): purchase cost and operating cost. Prices of storage water heaters vary among models with different features. They also vary by manufacturers, dealers, and regions of the country where they are sold. Some representative dealer prices for selected brands with standard features are shown in the table below.

Efficiency Life-Cycle Cost
Conventional Gas Storage Tank 55% $2,544
Conventional Electric Storage Tank 90% $5,495
High-Efficiency Gas Storage Tank 62% $2,385
High-Efficiency Electric Storage Tank 94% $5,362
Gas Tankless 70% $2,243
Electric Tankless 100% $5,590

Source: Sears, Betterpropaneshop.com

Often, the least expensive water heaters are the most expensive to operate. Life cycle costs, which take into account both the initial costs and operating costs of water heaters over their estimated useful lives, provide a more accurate representation of true equipment costs. As seen from the table below, gas water heaters tend to be more economical than electric ones over the long run.

Life-Cycle Costs of Different Types of Water Heaters*

Efficiency Life-Cycle Cost
Conventional Gas Storage Tank 55% $2,544
Conventional Electric Storage Tank 90% $5,495
High-Efficiency Gas Storage Tank 62% $2,385
High-Efficiency Electric Storage Tank 94% $5,362
Gas Tankless 70% $2,243
Electric Tankless 100% $5,590

Source: American Council for an Energy-Efficient Economy