Also known as a mini-split system, an air source heat pump (ASHP) is an energy-efficient heating and cooling system. They are popular in Europe, as well as in southern and tropical climates. However, the technology has advanced in recent years and it is a myth that mini-split systems do not work in colder climates. The system operates on the same heat transfer principles as a ground source heat pump. The main difference is:
- A ground source heat pump (also known as a GSHP or geothermal system) extracts or rejects heat from/to the earth, which stays at a constant temperature all year round (~57 degrees). GSHPs require underground drilling.
- An air source heat pump extracts heat from the air, which changes temperature based on the season. No drilling required.
- Both systems are highly efficient, however, due to the fact that a GSHP extracts heat from a source at a constant temperature, the efficiency is subject to less fluctuation.
In the heating mode, cold liquid refrigerant coils extract heat from the outside air (even though the air can be cold, there is still energy that can be extracted). The refrigerant is compressed into a vapor (which heats it up) and then flows to the indoor coils (heat exchangers) distributing heat through your home. The refrigerant condenses back into a liquid and the process repeats. The heat pump also has a reversing valve that provides cooling by absorbing heat from inside your house and distributing it to the outside.
- More energy efficient than traditional HVAC systems.
- Up to 40% more efficient than window air conditioning units.
- Little to no duct work required (Up to 30% of energy loss occurs through duct leakages).
- Only uses the exact amount of energy needed to maintain comfort.
- Most are Energy-Star-rated and qualify for state and federal tax credits, as well as local utility rebates.
- Require little maintenance.
- Built-in allergen filtration system.
- No well drilling required.
Tips for Using Your Mini-Split
- Adjust for comfort, not a specific temperature. [Don’t set it at 80 in the winter.]
- Don’t direct airflow at sitting area.
- Minimize use of backup system.
- Use “Auto-fan” mode.
- Clean filters and outdoor unit regularly.
- Ignore cycling and gurgling noises, these are normal.
- Keep service contact information.
- Initial investment. An air source heat pump can cost anywhere from $500 to $6,000; depending on the model. However, with government incentives and its energy efficiency, the system will help you save in the long run.
- Requires backup heating. Most heat pumps use an auxiliary heater which uses electricity to generate heat if the pump is not working efficiently.