An air source heat pump (ASHP) can provide both heating and cooling by utilizing the principles of heat transfer. Here's a simplified explanation of how an ASHP works for both functions:
Heating Mode:
- The ASHP extracts heat from the outdoor air, even in colder temperatures, using a refrigerant.
- The outdoor unit of the ASHP contains an evaporator coil that absorbs heat from the air and converts the refrigerant from a liquid state to a gaseous state.
- The gaseous refrigerant is then compressed by a compressor, which increases its temperature and pressure.
- The heated refrigerant flows through a condenser coil located indoors, releasing its heat to the surrounding air.
- A fan or blower blows air across the warm condenser coil, distributing the heat throughout the building.
- The refrigerant, now cooled and in a liquid state, returns to the outdoor unit, and the process repeats.
Cooling Mode:
- The ASHP reverses the cycle by absorbing heat from the indoor air and releasing it outdoors.
- The refrigerant absorbs heat from the indoor air as it passes through the indoor evaporator coil.
- The absorbed heat causes the refrigerant to evaporate and turn into a gas.
- The gaseous refrigerant is then compressed by the compressor, raising its temperature and pressure further.
- The hot refrigerant passes through the outdoor condenser coil, where it releases heat to the outdoor air.
- A fan or blower blows air across the condenser coil, aiding in the heat dissipation.
- The refrigerant, now cooled and in a liquid state, returns to the indoor unit, and the process repeats.
By reversing the flow of the refrigerant and adjusting the direction of heat transfer, an ASHP can switch between heating and cooling modes. The system uses the outdoor air as a heat source or heat sink, depending on the desired temperature adjustment. However, it's important to note that the efficiency of an ASHP can vary depending on the outdoor temperature, so extreme climates might require supplementary heating or cooling methods.