How Do Heat Pumps Work:Types,Functions,Benefit,Maintenance

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By Debarghya Roy

Heat pumps are a versatile source of heating and cooling for homeowners. Not only are they energy efficient and cost-saving, but they can also provide climate control with less stress to the environment.

This blog post explores how heat pumps work in detail from understanding the science behind them to their advantages over traditional HVAC systems.

Definition Of Heat Pumps

How Do Heat Pumps Work

Image: Heat Pump

A heat pump is a two-component appliance that uses refrigeration technology and electricity to provide heating and cooling for homes. 

Technically, it is a mechanical-compression cycle refrigeration system that can be reversed to either heat or cool a controlled space.

 Explanation Of Heat Pumps

Heat pumps extract heat from sources such as surrounding air, geothermal energy stored in the ground, or nearby sources of water or waste heat from a factory.

Heat pumps can generally be divided into three main categories, 

  • Ducted air-source units which use outdoor ambient temperature to warm up or cool down an indoor environment.
  • Geothermal units that utilize the steady temperature of underground soil/water temperatures regardless if it’s summer or winter.
  • Absorption units that work through evaporating liquid ammonia using solar panels’ generated electricity instead of natural gas.

Science Behind The Working Of Heat Pumps

Heat pumps utilize the principles of thermodynamics and heat transfer to absorb external thermal energy from outside air and to then move it inside a closed loop for use as cooling or heating. Discover more about how these systems work by reading on.

The Refrigeration Cycle 

At its core, a heat pump works by taking in energy at a low temperature and releasing it at a higher temperature due to thermodynamic processes.

The process of transferring heat is known as the refrigeration cycle or vapor-compression cycle, which involves using mechanical work to compress and expand gasses.

The main component inside any typical air conditioner or refrigerator is its evaporator coil, which contains liquid refrigerants such as Freon. 

When compressed gas passes through an expansion valve into this coil, it quickly absorbs large amounts of thermal energy as it boils off into vapor form thus cooling the nearby source.

Heat Transfer

These specialized units take existing cold outdoors temperatures in collected gas form collect them inside until we have enough warm air flow entering our living spaces.

Instead of pulling hot air out from outside and releasing cooler air indoors like normal AC units.

This cooled air is then circulated throughout your home via interconnected ducting systems so that your entire living space can benefit from regulated temperatures without relying solely on standard electric resistance heating methods like baseboard radiators or wall-mounted furnaces.

But while freezing temperatures may help cool indoor environments during summer months, you still need some way of collecting valuable heat energy during wintertime. 

Components Of A Heat Pump

At its simplest level, a heat pump comprises five key components: compressor, condenser, evaporator, expansion valve and reversing valve.

Compressor  Of A Heat Pump

The compressor acts as the power center for the unit by compressing refrigerant gas – typically Freon that’s already warm and raising its pressure so it can absorb more heat from outside air or ground.

Condenser  Of A Heat Pump

The condenser then re-condenses this high-pressure vapor into liquid form while releasing any latent heat collected before flowing it through other components.

Evaporator  Of A Heat Pump

This is done by using lower pressure molecules to draw in surrounding much colder outdoor air which cools off the vapors before they enter back into our home’s living spaces finally completing their cycle only ready to start again when called upon via activation switches on your wall thermostat setting inside your house.

Expansion Valve  Of A Heat Pump

Expansion valve is connected to the evaporator where the system’s cooling operation begins.

Reversing Valve  Of A Heat Pump

The reversing valve further speeds up this transfer process by changing direction depending on whether you need cooling or warming with efficiency coming primarily from both compression work required.

Heating Mode Of Heat Pumps

Heat pumps operate on a refrigeration cycle, using a reversing valve to switch between heating and cooling modes. 

In heating mode, heat pumps absorb naturally occurring heat from the air around the home or ground outside and then translate it into thermal energy.

This thermal energy is then propelled within sealed pipes throughout the building until it enters an indoor evaporator coil where it is dispersed throughout via an indoor fan system.

Cooling Modes Of Heat Pumps

In cooling mode, this process reverses; warm air produced in the house is drawn into the evaporator coil and expelled outside through condenser coils releasing cool air inside of the home.

The refrigerant used helps facilitate this transfer of heat by blocking temperatures at certain levels when passing back and forth through these coils specific for either heating or cooling purposes.

Types Of Heat Pumps 

Heat pumps are a common heating and cooling choice for many residential homes. They are widely used due to their energy efficiency and environmental friendliness, as well as the fact that they can provide both heating and cooling modes.

Geothermal Heat Pumps

These use water instead of air that flows through pipes which are buried underground and then transfer it to both ways at its consistent temperatures.

Main Benefits Of Using Geothermal Heat Pumps

Geo provides the highest level among all other thermal pump types reaching upwards 450% coefficient rating (as opposed 300%).

No need to worry about issues related to cold weather like frozen condenser coils talked about above leading longer lasting machines little maintenance duties required–depending install monitoring upkeep controls may also vary accordingly.

Additionally certain areas really benefit greatly from geo setups remote locations particularly where access grid power hit miss limits thus refrigerant running maintaining life cycle functional standard rates.

Disadvantages Of Using Geothermal Heat Pumps

Including initial setup excavation work further causing disruption of land ecology subsequently distant regions are slightly expensive to operate compared to other noise disturbances from installations.

Carefully consider effects upon neighbors’ requirements letter approval any applicable local governing bodies aware project’s intent prior continuing development too costly switch regular mains electricity remain insufficient resource reserves encounter arise.

How Do Geothermal Heat Pumps Work?

The science behind geothermal heat pumps is based on the principle of thermal insulation and involves two key components. 

An earth loop where circulated liquid absorbs available heat, and a refrigeration cycle between two different temperatures that transfers absorbed latent energy into usable form.

Through this process it can both extract warmth directly from the ground during summer months and pump heated fluid back down when temperatures drop below freezing  making it one of the most efficient HVAC methods available today with potential SEER ratings up to 35+.

One advantage of using this technology is its ability to provide highly effective replacements for traditional fossil fuel sources like oil or gas boilers as well as electric resistance heating systems by reducing related installation costs over time.

Air Source Heat Pumps 

This type of system uses outside air to provide heating or cooling indoors. 

The main advantages of these systems include their cost effectiveness since they leverage existing ductwork whereas other kinds require new installation costs, their very efficient operation when installed correctly, they can reach up to., 300% efficiency.

In fact depending upon climate zone models can provide off 3x their rated output even during winter months offsetting energy expenses significantly compared to other mechanical non renewable options available today.

Typically used as an efficient alternative to traditional electric resistance heating systems such as furnaces or boiler and central AC units like split ducted ACs.

But some drawbacks include lower relative energy savings compared to ground source heat pumps in cold climates because cold freezes them over easily resulting in higher maintenance costs.

How Do Air Source Heat Pumps Work?

These are HVAC systems that collect heat from the surrounding air and extract it for use in heating, cooling, or dehumidification. 

Air is drawn in from the outdoors using an outdoor unit which then circulates it into your home through ductwork via an indoor evaporator coil and fan motor combo.

  • This will either pull out hot air during summer months or warm air during winter months depending on the desired climate setting inside. 
  • This type of system relies on refrigerant, a fluid which flows through copper coils installed outside and inside the system.
  • The compressor, the main component of any HVAC system, raises the pressure of the refrigerant and forces it to circulate throughout these two sets of coils. 

Hybrid Heat Pumps

Hybrid heat pumps are a type of dual fuel heating system that combines an electric heat pump and a gas furnace. 

It is becoming increasingly popular among homeowners looking to reduce their energy bills while still having access to reliable, comfortable heating.

How do hybrid heat pumps work? 

The electric heat pump part of the system extracts any available ambient or outside air and transfers it into the home using refrigerant-based coils, delivering temperatures up to approximately 35 degrees Celsius depending on the outdoor temperature.

Hybrid heat pumps use electricity to move existing sources, such as air or ground temperature, from one place to another for both cooling and heating purposes instead of creating new ones with fossil fuels like traditional furnaces and air conditioners do.

For example, when used for summer cooling applications they transfer warmth outside or collect waste hot factory exhausts and dissipate them away from living spaces inside structures thereby lowering overall ambient temperatures indoors.

Cost Comparsion Of Different Types Of Heat Pumps

Heating With Heat Pumps

Heat pumps use a small amount of electricity to compress and transfer heat from the outdoors, making them incredibly energy-efficient systems for providing comfort in the cold winter months.

Variation Of Heat Output With Temperature

When using a heat pump, the output of heated air or cooled air varies with temperature. 

Heat pumps use refrigerant to absorb heat from the outdoor environment and transfer it indoors for heating when needed.

The output is affected by colder temperatures in the winter at 0°F (-18°C) outdoor temperature.

A 3-ton (30,000 BTU/Hr) unit will provide only 1 ton (12,000 BTU/Hr) of actual capacity due to up to 40-50% reduction in efficiency even when running at optimal conditions.

With this basic understanding engineers have developed climate zones and tailored their systems accordingly.

one should select their equipment based on extremes associated with their geographical location and variations within those parameters over time.

Supplemental Heat Sources

Supplemental heat sources are supplementary heating devices, such as electric resistance heaters, which can be used in conjunction with a heat pump system to provide additional warmth during periods of extended cold weather.

While most conventional furnaces are 100% reliant on supplemental sources for their heat when the temperature dips below the optimal range for hot air production approximately 17-20 Celsius degrees.

Heat pumps still produce output temperatures that fall within this operating range and deliver up to three times more heat into the home than the electricity they consume.

However, using supplemental sources can help reduce the strain on a system’s compressor. 

For example, some models of hybrid systems automatically turn on their supplemental source once outdoor temps reach 4ºC; then shut it off at 10º C.

Cooling With Heat Pumps

Heat pumps can effectively cool your home by absorbing unwanted heat from outside and transferring it inside to keep the temperature at a comfortable level.

Variation Of Heat Removal With Temperature

Heat pumps have the ability to both heat and cool a space, an advantage they have over traditional heating systems. 

In cooling mode, which is frequently referred to as air conditioning in a residential setting, heat pumps work by removing unwanted heat from inside a structure.

A key component in this process is the reversing valve which allows for quick changes between cooling and heating modes allowing for immediate temperature control when necessary.


Heat pumps provide an energy-efficient way of cooling homes while simultaneously removing excess moisture, which is referred to as dehumidification. This process works by first cooling the air, which reduces its capacity to hold water vapor.

As a result, some of this vapor condenses into liquid called “dew” and a portion of it evaporates collectively known as the process of refrigeration

  • Heat pumps are capable of achieving higher levels of dehumidification than standard central air conditioners due to their higher efficiency ratings.
  • This translates into greater comfort in humid climates and better indoor air quality.
  • In addition, portable heat pump dehumidifiers can also be used for controlling humidity levels in specific areas or rooms without running up large electric bills or using mechanical ventilation systems for whole-home moist removal.

Advantages Of Heat Pumps

Heat pumps offer numerous advantages over traditional HVAC systems, such as higher energy efficiency and cost savings, versatility for both heating and cooling needs, environmental benefits and reduced noise levels.

Energy Efficiency And Cost Savings

Heat pumps are an energy-efficient and cost-effective alternative to traditional gas or oil furnaces for heating homes. 

By transferring heat from the outside environment into a home, heat pumps reduce energy consumption by about 40 to 60 percent compared to conventional systems.

Seattle City Light has reported that using their “air source” product can save homeowners up to 26% on annual heating costs over typical baseboards or radiators utilizing natural gas or oil while also improving indoor air quality through better ventilation control options enabled by modern inverter driven units.

Versatility For Both Heating And Cooling

Heat pumps are a versatile solution for heating and cooling that can be used in either residential or commercial buildings. 

Compressors play a major role in this process as they help move the thermal energy between two points by transferring refrigerants through pipes and coils.

One of the key features of modern heat pumps is their ability to adjust their temperature output depending on whether they are set up for heating or cooling.

This process relies on reverse valves situated inside the heat pump’s compressor unit which change cycle direction according to user selection, allowing them to switch between modes easily.

Environmental Benefits

Heat pumps are an effective method to reduce emissions, conserve energy, and promote sustainability in the home. 

The US Environmental Protection Agency reports that savings of up to 50% on annual electricity costs can be achieved with a correctly-installed heat pump system compared with electric resistance heating.

Additionally, for some climates, it is possible to collect renewable energy from sources such as geothermal or air in order to power the pumps. This makes growing numbers of people opting for this eco-friendly option over more harmful electrical appliances seen across many countries.

Quiet Operation And Improved Indoor Air Quality

As an all-in-one HVAC system, heat pumps offer several benefits, including improved indoor air quality,  energy efficiency and quiet operation in mind

Through use of a filtration system that removes pollutants and allergens from the air, residents can enjoy better air quality without having to worry about loud noises or excessive energy costs.

The compressor used in most traditional home cooling systems often emit high decibel sounds, creating potentially disruptive noise pollution within the household’s interior space.

Smart designs employed by modern heat pump technology make them extremely quiet compared to more standard heating/cooling units emitting only 58 dB’s which is less than half of a traditional AC unit at full speed (125 dB’s).

Maintenance And Care For Heat Pumps

In order to get the most out of a heat pump system, regular inspections and other maintenance tasks should be performed.

Filter Cleaning And Replacement

Filter cleaning and replacement is a crucial part of heat pump maintenance that should not be overlooked. A clogged filter can affect the efficiency, lifespan, and overall performance of your heat pump system.

The most common symptom of a dirty or clogged filter is for the system to continuously turn on and off, which is known as short cycling.

Professional maintenance visits are also important as they provide opportunities to stay ahead of common issues related to heat pump operation, such as insufficient heating during cold weather due to blocked airflow over compressor wires or clogged filter systems which can reduce cooling capacity significantly.

Professional Inspections And Tune-ups

Regular professional inspections and tune-ups that can help identify any potential issues with the system before it becomes a major problem.

During an inspection, technicians will check 

  • Refrigerant levels
  • Clean and inspect coils in both the outdoor condenser unit and indoor evaporator units adjust motors
  • Lubricate fan motors 
  • Check air flow out of vents 
  • Inspect flue connections at furnaces and boilers or change hydraulic oil filters on baseboard radiators
  • As well as look for signs of improper wiring connections

Seasonal Adjustments

Proper and timely seasonal adjustments are essential for ensuring optimal performance and longevity of modern heat pumps. 

In addition, bleed valves must be adjusted according to current climate conditions while changes in temperature should prompt professionals to evaluate the Ice Thermal Storage System (ITSS) implementation model used by their system if needed.

For air-source models, these include clearing the outdoor unit of vegetation as well checking refrigerant levels at regular intervals to ensure system efficiency.

Ground-source heat pumps may also require periodic inspections, such as once a year, to identify any potential issues. 


For any home, commercial space, or even an industrial building, heat pumps offer efficient and cost-effective climate control. Heat pumps can provide the perfect balance of heating and cooling needs with one device that uses a relatively low amount of energy to do so.


What is a heat pump?

A heat pump is a device that transfers energy from one place to another. It takes warm air usually outside the home and moves it inside, or vice versa, cooling or heating your space depending on the season.

How much does it cost to run a heat pump per month?

The cost of running a heat pump can vary depending on usage, efficiency ratings, climate, and size but typically costs about 50% less than traditional HVAC systems.

Can I install a different type of backup system with my heat pumps?

Heat pumps are compatible with electric, oil, or gas backup systems so you have more flexibility when installing them in your home.

Are air conditioning units considered as heat pumps too?

All traditional air conditioners are technically classified as ‘heat pumps’ since both processes remove warm air from the indoors for cooling purposes.

What types of Heat Pumps exist and how do they differ?

There are ductless mini split systems designed for smaller areas; geothermal which uses underground loops instead of outdoor coils; and hybrid/dual fuel models which use two separate sources to save energy while maintaining comfortable temperatures throughout heating/cooling seasons.

Heat Pump