How Do Heat Pumps Work?

Heat pumps operate on the principle of heat transfer rather than heat generation. They use a refrigeration cycle to move thermal energy from a cooler space to a warmer space, or vice versa. This process uses much less electricity than generating heat directly, making them highly energy efficient.

A heat pump consists of four main components: 1) Evaporator (absorbs heat), 2) Compressor (pressurizes refrigerant), 3) Condenser (releases heat), and 4) Expansion valve (controls refrigerant flow). These work together with refrigerant to move heat between indoor and outdoor units.

The refrigeration cycle has four stages: 1) Evaporation - liquid refrigerant absorbs heat and becomes gas, 2) Compression - gas is compressed, raising its temperature, 3) Condensation - hot gas releases heat and becomes liquid, 4) Expansion - pressure drops, cooling the refrigerant. This cycle repeats continuously.

Heat pumps are more efficient because they move existing heat rather than creating it. For every 1kW of electricity used, a heat pump can move 3-4kW of heat energy. Electric heaters convert 1kW of electricity into only 1kW of heat, making heat pumps 300-400% more efficient.

Even in cold weather, there's still heat energy in the outside air. Modern heat pumps can extract heat from air as cold as -15°C. The refrigerant evaporates at very low temperatures, allowing it to absorb heat even from cold air. However, efficiency does decrease as outdoor temperatures drop.

In heating mode, heat pumps extract heat from outside air and pump it inside. In cooling mode, they reverse this process - extracting heat from inside air and pumping it outside. A reversing valve changes the direction of refrigerant flow to switch between modes.