Heat pumps and air conditioners ... Consider a heat pump if you need to heat your home quickly and efficiently. In cooler months, a heat pump utilizes a reversing valve that switches the system ...

Heat pumps are nearly identical to central air conditioners but use a reversing valve to provide both cooling ... a contractor to either install a heat pump or make additional efficiency ...

The use of environmentally damaging gases in air conditioners and refrigerators could become redundant if a new kind of heat pump lives up to its promise. A prototype, described in a study ...