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Replace a Fossil Fuel Furnace to Lower Emissions—and Your Bills

What you need to know about buying a heat pump.

relates to Replace a Fossil Fuel Furnace to Lower Emissions—and Your Bills

Illustration: Felix Decombat for Bloomberg Green

Whether you want to reduce the greenhouse gases your home produces or lower the cost of your utilities, a heat pump might seem like a good idea. Here are some important factors to consider before you make a purchase.

The most commonly installed are air-source heat pumps, which resemble air conditioner units that sit outside your house. During winter, a liquid refrigerant in a copper coil extracts heat from the atmosphere as warm air naturally moves toward the cold. The heat transforms the refrigerant into a cold gas and a compressor then pressurizes the gas, raising its temperature and heating the air inside the house. The reverse happens in hot months, when heat inside the house is absorbed and transferred outside. That’s increasingly useful in temperate areas of the U.S., where people typically don’t have air conditioners but are being hit with climate-change-fueled heat waves.