What Are Heat Pumps and How Do They Work?

Jun 11, 2024 | H.E. Rieckelman

Heat pumps are a system designed to provide comfort through heating and cooling an area of a building, functioning very similarly to a furnace and air conditioner combined into one unit. They are typically installed on the floor or behind walls within the space they are heating/cooling and commonly seen used in commercial, industrial, and residential applications.

Heat pumps don’t generate heat but absorb ambient heat and move it from one place to another, such as into a building or a water source. Due to this factor, heat pumps are a more environmentally friendly option compared to traditional heat distribution equipment that only primarily use electricity as their power source running at lower efficiencies. This device operates using a refrigeration cycle to absorb and move the ambient heat; additionally using air or water to extract the heat from the refrigerant, which will move the heat around the designated area. In warmer months, heat is extracted from indoor air and released to the outside. Whereas in colder months, heat is pulled from outdoor air and transferred indoors. It accomplishes heating and cooling using a reversing valve that changes the direction of the refrigeration flow during different climates.


Different Types of Heat Pumps


Air-to-Air: The most common type of heat pump due to the versatility of the location of the unit. The heat pump uses two coils, one inside and outside, to transfer heat in or out of the building.

Air-to-Water: The heat pump uses a coil outside that connects to a hot water tank where the refrigerant transfers heat to water through a heat exchanger. The heated water can be provided to radiators, sinks, showers, etc. while also used for comfort heating and cooling.


Unlike air source heat pumps using a fan and coil outside, a ground source heat pump uses a coil that is buried underground and uses the ground as a thermal battery. The underground coil uses a water and antifreeze mixture to absorb heat from the ground, which is pumped into a plate heat exchanger to transfer the heat to the refrigerant in the main system. A ground source heat pump doesn’t always need a reversing valve to achieve heating and cooling because the pump for the underground coil can push the water mixture both ways, in which the plate heat exchanger will imitate a reversing valve. A ground source heat pump can have an air-type or water-type system with a closely identical system layout as the air and water type systems in air source heat pumps.


Similar to a ground source heat pump, heat is extracted from a body of water, such as a river, pond, or underground water source. There are two main types of water source heat pumps:

Closed Loop: Uses a coil that is submerged in a water source that absorbs heat with a water and antifreeze mixture and transfers it using a pump through a plate heat exchanger.

Open Loop: Pumps water from a water source into a plate heat exchanger. Same as a ground source heat pump, it uses a pump that can push the water mixture both ways and a plate heat exchanger together act as a reversing valve to achieve heating and cooling.


Why Use Heat Pumps Rather Than Fan Coils


Similar to heat pumps, fan coils (FCU) are designed to provide comfort through heating and cooling an area of a building. Fan coils transfer heat using hot and cold water in coils, depending on the climate, which then will heat or cool air that is blown over the coils. Instead of moving heat between inside and outside of the building, fan coils will draw air from the outside and circulate it through a room. Fan coils can operate alone or connected to a central air handling unit, which can provide to multiple FCUs.


Heat pumps are more energy efficient, eco-friendly, provide consistent comfort, and provides potential grants and rebates.



Heat pumps installation is more costly, less flexible, and more prone to damage and malfunction.


Fan coils have flexible installation, compatible with existing systems and are simple to maintain.


Fans coils are less efficient, less eco-friendly, and has a chance to create uneven room conditions.


Installation: Fan coils can be mounted on to any surface, on the wall, ceiling, or floor, due to their smaller size and easier access. Additionally, FCUs can connect to existing ductwork or used as a ductless system. Heat pumps are more restricted on where it can be installed and requires more space.

Maintenance: Both require regular maintenance to ensure optimal performance and longevity; however, both take different maintenance procedures. Heat pumps require annual servicing to ensure the components are in good condition, whereas fan coils require periodic cleaning and inspection to ensure constant airflow and efficiency.

Performance: Heat pumps are typically louder during their peak operation where as fan coils tend to be quieter if maintained well. Additionally, heat pumps can operate at higher temperatures, requiring less energy to move heat. As a result, heat pumps deliver three times more heat energy than consumed in electricity, succeeding fan coils where they can deliver up to 100% of heat energy in water.

Economics: Fan coils are generally cheaper with a cheaper installation cost and maintenance cost, whereas heat pumps are more expensive in those aspects. However, depending on the region, heat pumps have cheaper operation cost and are liable for potential government rebates and grants.


Where To Find The Right Heat Pump?

H.E. Rieckelman houses a line of Bulldog water-source heat pump units and a line of Clivet air-source heat pump units, both serving the same purpose but for different applications. Bulldog develops water source heat pumps that are the forefront of the residential and commercial heat pump industry and Clivet specializes in air source heat pumps and is the leading manufacturer in roof top heat pump units, particularly for decarbonization. For any questions about new units or spare parts, visit our contact page to reach out and learn more about what heat pump is right for you.


By: Gabriel Duarte