Rheem says its High-Efficiency Condensing PDV Water Heater represents the first use of high-efficiency condensing technology in a residential-class tank heater. (Residential models fire at a maximum 75,000 Btu and must have a safety feature called flammable vapor ignition resistance.) The unit has an energy factor of 0.80 and comes in 40,000-Btu gas and 36,000-Btu propane versions. Its high efficiency is achieved in part by heat-exchanger coils that route exhaust gas through the tank twice. The unit costs $1,400 to $1,600, not including installation; estimating operating cost is $228 per year.

Rheem, 800/621-5622, rheem.com.

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