What is a Heat Pump: A Beginner’s Guide

Last Updated on October 21, 2021 by Kimberly Crawford

A heat pump is a highly functional and energy-efficient cooling and heating device. 

A heat pump is a machine that uses thermal energy to transport heat from one location to another. Our refrigerators are an excellent example of this since they use the cooling of a liquid and its evaporation to reduce and control the temperature of the storage compartment. 

Heat pumps need a small amount of power to function, and they are considered very efficient and environmentally friendly since they do not rely on fuel combustion to generate heat. They are capable of providing warmth throughout the winter, even at -20 degrees Celsius.

Related: 5 Worst Heat Pump Brands and 7 Most Reliable Brands (Buying Guide)

Components of a Heat Pump

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When warming our homes and offices, heat has a beneficial property: it naturally flows from high to low. A heat pump reverses this process by drawing air from the outside, warming it up, and then supplying it to your home.

On the outside of the air source heat pump is a series of refrigerant-filled coils through which an impeller or fan pulls outside air. The fluid in the refrigeration coils absorbs the heat and evaporates as it heats up. This gas is then compressed, substantially increasing the temperature.

The heat then travels around the structure, eventually reaching the inner coils where heat is discharged. Meanwhile, the refrigerant flows back outdoors, where it absorbs heat, and the process begins again. The usable heat generated is fed into air vents and distributed throughout the building or utilized to heat the water that feeds radiators.

Ground source heat pumps operate in a somewhat different manner, drawing their energy from the ground or basement. These devices use either closed system ground pipework or open-loop water piping. Closed-loop systems use a steady flow of coolant to fulfill the same function as a central air pump, while open-loop systems use water from a well or lake.

For bigger installations, you may choose to consider an absorption heat pump, which operates similarly to an air source heat pump but utilizes ammonia rather than a refrigerant. These are often utilized in industrial environments but have been increasingly used in large commercial and residential complexes in recent years.

The second critical component of every heat pump is the ducting that distributes heat from the primary source to the house’s rooms. Ducting is sometimes a source of debate when renovating property since it may be invasive and costly to install. As a result, several household homes choose for easier-to-install mini-split heat pumps.

One of the most recent developments in heat pump technologies is thermodynamic paneling that uses both ambient and solar energy to heat your water and rooms. These are often installed mainly on the side of a home, but they may also be placed on the roof and resemble solar panels.

The Advantages and Disadvantages of Heat Pumps

While heat pumps are not genuinely renewable technology due to their dependence on a small amount of power from the grid, they are an extremely effective method to keep your home or workplace warm.

For the United Kingdom, where the climate is moderate, heat pumps can operate all year, even at lower temperatures seen during the winter. The issue with older buildings would be that heat is generated at a lower temperature than other systems, which means that homes that are vulnerable to droughts or are not well insulated would struggle to maintain the desired ambient temperature.

Although heat pumps and air conditioning have similarities, there are also some differences, that you can check here: serviceemperor.com/blog/heat-pump-vs-ac.

How Heat Pumps Work (in Cooling Mode)

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One of the most critical concepts to grasp about heat pumps and the process of heat transfer is that thermal energy naturally gravitates toward locations with lower temperatures and pressure. Heat pumps use this physical trait by bringing heat into touch with cooler, low-pressure environments, allowing the heat to move naturally. This is the principle of operation of a heat pump.

At the indoor coil, which also serves as the evaporator, liquid refrigerant is pushed via an expansion mechanism. Cool air is then pumped throughout the home’s ductwork. As a result of absorbing the thermal energy, the liquid refrigerant has increased in temperature and evaporated into gas form.

A compressor compresses the gaseous refrigerant. The pressurization of the gas allows it to heat up. The system transports the hot, pressurized coolant to the coil in the outside unit.

In cooling mode, a fan in the outside unit pushes outside air over the coils, which act as condenser coils. Because the outside air is colder than the hot compressed air coolant within the coil, heat energy is transferred from the coolant to the outside air. As the refrigerant cools, it compresses back to a liquid state. The system is pushed with warm liquid refrigerant to the expansion valves on the interior units.

The expansion valve decreases the pressure of the hot liquid refrigerant, significantly cooling it. At this time, the refrigerant has condensed to a liquid form. It is ready to be moving backward to the indoor unit’s evaporator coil to restart the cycle.

Related: 10 Popular Types Of Home Air Conditioners (Buying Guide)

How Heat Pumps Works (inn Heating Mode)

In heating mode, a heat pump functions similarly to cooling mode. However, the refrigerant flow is reversed through the appropriately called reversing valve. Due to the flow reversal, the heating source has become the external air. The heat energy is discharged into the home. The exterior coil now serves as an evaporator, while the interior coil serves as a condenser.

The method is the same in terms of physics. The cool liquid refrigerant absorbs heat energy in the outside unit, converting it to chilly gas. The cold gas is subsequently compressed, converting it to hot gas. The interior unit cools the hot gas by flowing air through it, heating it, and condensing it to a warm liquid. As the heated liquid reaches the outside unit, it is released of pressure, converting it to cold liquid and restarting the cycle.


A heat pump uses a reversing valve to reverse the direction of refrigerant flow and so heats or cools a residence. The evaporator coil is blown over, delivering heat energy from air to the coolant. This heat energy is carried by the coolant to a condenser and released when air is blown over the coil by a fan. This mechanism transfers heat from one location to another.