HOW HEAT PUMPS WORK & OTHER TYPES OF HEAT PUMPS
The Science Behind Heat Pumps Heat pumps rely on the refrigeration cycle to heat and cool your home. The refrigeration cycle consists of four key components: a compressor, a condenser, an expansion valve, and an evaporator. Cooling Mode. The first component, the compressor, is the heart of the system because it’s responsible for circulating the refrigerant that moves heat out of your home. When refrigerant reaches the compressor it’s in a gas state and has a low
temperature and low pressure. As the compressor pulls in the refrigerant, it mechanically compresses it to raise the refrigerant’s pressure and temperature. It’s important for the refrigerant to be at a higher temperature than the surrounding air because it helps with the heat transfer process – heat energy naturally wants to move to areas with lower temperatures and less pressure. The high-temperature refrigerant then moves into the condenser, where its heat is rejected into the surrounding area (the outdoor air). If you’ve ever felt warm air coming from the bottom of your refrigerator, this is your condenser transferring warm air out of the fridge. When the refrigerant leaves the condenser, it changes into a liquid state but remains at a high pressure. It then enters the expansion valve, where the refrigerant’s pressure is lowered before it moves into the last step of the refrigeration cycle; the evaporator. The evaporator consists of an evaporator coil, which is what the low-temperature liquid refrigerant flows through, and a fan. The fan blows warm air from inside your home across the evaporator coil, where the air’s heat energy is absorbed by the cooler liquid refrigerant. The resulting cool air is then pushed back into your home. The process of absorbing heat energy has caused the liquid refrigerant to warm up, and it evaporates back into gas form. The refrigeration cycle is now complete, and the gas refrigerant moves onto the compressor to begin the cycle again. Heating Mode. When you hear the term refrigeration cycle, you likely think of your refrigerator, and that it makes things cooler. So how does a heat pump, which relies on the refrigeration cycle, provide heating too? Heat pumps are equipped with a unique feature called a reversing valve. A reversing valve allows a heat pump to reverse the refrigeration cycle, pulling heat from outside to heat your home during the colder months. Even though it may be cold outside, there is still heat energy in the outside air. A heat pump can absorb that energy and use it to heat your home. Because heat pumps transfer heat rather than producing new heat, they are 2-4 times more efficient than other heating system options.
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ELECTRIC HEAT PUMP CUSTOMER BUYING AND OPERATION GUIDE FOR SINGLE-FAMILY HOMES
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