Keep your home comfortable and energy-efficient with a modern heat pump!
In recent years, many homeowners have started looking for a green climate control solution.
As a result, heat pump technology has gained considerable popularity as an alternative to air conditioners and traditional heating systems.
But how does a heat pump work? Let’s find out more about heat pump advantages!
What Is a Heat Pump?
A heat pump is a mechanical-compression cycle refrigeration system that can be used for cooling and heating.
Unlike traditional air conditioners and furnaces, Heat pumps utilize electrical energy and refrigerant to absorb and transfer heat from one place to another.
This allows them to transfer heat from the air or ground outside of a building to the inside or vice versa, making them an efficient and cost-effective option for heating and cooling.
They consist of two major components: an evaporator and a condenser.
When functioning properly, heat pumps represent an energy-efficient option that can circulate either warm or cold air inside a home.
Components of a Heat Pump
Heat pumps consist of an indoor unit and an outdoor unit.
The outdoor unit looks similar to the outdoor compressor box of an air conditioning system, while the indoor unit handles air transfer inside the home.
Both indoor and outdoor units contain various sub-components, like condenser coils and evaporator coils.
Let’s take a closer look at the main components of a heat pump.
⚙️ Outdoor Unit
The outdoor unit has a coil that switches functions depending on whether homeowners use their heat pumps to heat or cool their homes.
The specialized coil functions as an evaporator coil in heating mode and as a condenser coil in cooling mode.
The outdoor unit’s fan blows air from outside the home and over the coil to create heat transfer.
⚙️ Indoor Unit
The indoor unit, commonly referred to as the air handler, also contains a coil and a fan—the coil functions similarly to the outdoor unit’s.
The indoor unit’s fan also functions the same way as the outdoor unit’s, except that the fan moves heat through the air ducts, distributing warm or cooled air to all rooms inside the home.
The refrigerant serves as a substance that undergoes repeated transitions from a liquid state to a gaseous state and back again.
As heat circulates through the heat pump system, the refrigerant either absorbs it or rejects it as needed.
The expansion valve regulates the flow of the refrigerant as it moves throughout the system. This allows for a reduction in both the temperature of the refrigerant and the pressure applied to it.
The reversing valve reverses the flow of refrigerant in the heat pump system. This allows the system to operate in two ways, switching between heating and cooling.
How Does a Heat Pump Work?
Heat pumps themselves do not generate heat but transfer heat from one place to another with the help of electrical energy.
A heat pump takes in heat energy from the outside air and transfers it indoors.
Heat pumps can also function as air conditioning systems by absorbing heat from the indoor air and transferring it outside.
Heat pumps can switch between heating and cooling modes based on the homeowner’s needs.
⚙️ Heat Pumps in Cooling Mode
How does a heat pump work in cooling mode?
The heat pump pushes liquid refrigerant through the expansion valve on the indoor coil to cool a home.
The refrigerant absorbs heat energy from indoor air blown over the coils.
The resultant cool air then gets blown through the ventilation ducts of the home.
This process causes the liquid refrigerant to turn into gas as it absorbs the heat.
The gaseous refrigerant then flows into the compressor, where it gets pressurized.
The pressurized gas acquires even more heat and moves through the system to the coil in the outdoor unit.
The fan in the outdoor unit blows outdoor air across the coils, which act as a condenser.
The difference in temperature and pressure between the hot refrigerant and the outside air allows the unit to expel heat into the atmosphere.
As the refrigerant cools down, it reverts into liquid form, which then gets pumped through the system to the expansion valve in the indoor unit.
The expansion valve reduces the pressure of the liquid refrigerant and cools it further.
This refrigeration cycle repeats itself until the heat pump achieves the required temperature.
⚙️ Heat Pumps in Heating Mode
How does a heat pump work in heating mode?
To heat a home, the reversing valve reverses the flow of refrigerant in the heat pump system.
This reversal causes the outdoor air to become the heat source.
The roles of the evaporator and the condenser also reverse.
The outdoor unit’s coil functions as the evaporator, and the indoor unit’s coil functions as the condenser.
The liquid refrigerant takes in heat while inside the outdoor unit and turns it into a cold gas.
The AC compressor applies pressure to the cold gas and heats it.
Air then passes over the newly created hot gas found inside the indoor condenser coil to warm the home.
As the air passes over the hot, gaseous refrigerant, the refrigerant condenses into warm liquid, flowing back to the outdoor unit.
As the liquid enters the outdoor unit, a metering device causes it to lose both pressure and temperature, cooling it down. This cycle repeats as needed.
Types of Heat Pump Systems
Heat pumps get classified into air-source heat pumps, water-source heat pumps, and geothermal heat pumps.
Each heat pump system collects heat from the air, water, or ground found outside the home.
Air Source Heat Pumps
Air-to-air or air-source heat pumps absorb heat from the outdoor air to warm the indoor areas of a home.
The outdoor air condenses under pressure until it achieves a temperature sufficient to keep the entire house warm.
Water Source Heat Pumps
A water source heat pump (WSHP) expels heat to a water pipe system in the summer and absorbs heat from the same system in winter.
Thus, WSHPs use water instead of air as a heat source to control the temperature of the refrigerant.
Geothermal Heat Pumps
Geothermal or ground source heat pumps use the earth as a heat source or heat sink. This type of heat pump exchanges heat with the earth to control the refrigerant’s temperature.
All heat pumps come equipped with a reverse operation that serves both heating and cooling purposes.
Other models can also heat water for use within a home.
Benefits of Heat Pumps
Ducted or ductless heat pumps do more than regulate the temperature inside a home. They provide several other benefits over alternative heating systems.
✅ Safety and Energy Efficiency
A heat pump remains safer and more energy-efficient than combustion-based heating systems, like oil burners or gas furnaces.
As a result, heat pump owners enjoy significant savings on their energy bills.
Since heat pumps utilize electrical energy, they leave a minimal carbon footprint, making heat pumps a more environmentally-friendly option.
A heat pump can heat and cool a home, eliminating the need for air conditioners and furnaces.
This can amount to an upfront heat pump cost reduction when deciding on a climate-control system for a home.
✅ Improved Air Quality
Heat pumps also keep indoor air quality at a healthy level.
Like an air conditioner, the heat pump filters air by removing dust, mold spores, smoke, and other particles.
During summer, heat pumps also act as dehumidifiers and can also reduce condensation in rooms during the colder months.
✅ Low Maintenance
Heat pumps also require little maintenance. A yearly check of the components keeps a heat pump running smoothly.
A heat pump can last as long as 50 years, although the average lifespan stands at 14.5 years.
Heat pumps remain a reliable, low-maintenance climate-control option that presents great value for money over other heating and cooling systems.
At What Temperature Do Heat Pumps Stop Being Effective?
Heat pumps owe their high efficiency to the constant nature of thermal energy.
Thermal energy remains in the air even in freezing temperatures.
As a result, heat pumps function best with outdoor temperatures above 40F (+4C) and begin to lose their efficiency when temperatures drop that mark.
Heat pumps function less efficiently than furnaces when temperatures drop below 25F (-4C).
This reduction in efficiency occurs because of the reduced levels of thermal energy present at lower temperatures.
For example, air at 0F (-17C) contains about 85% of the thermal energy present at 70F (21C).
This difference in thermal energy causes a drop in the heat pump’s efficiency.
As a result, the heat pump works harder to make up for the difference between outdoor and indoor temperatures, which results in more electricity consumption.
Heat pumps remain effective at cooling a home’s indoor areas, even at high temperatures.
Counterintuitively, the warmer the outside air, the higher the heat pump’s efficiency.
Cold outdoor temperatures reduce its energy efficiency as a cooling system.
Extremely cold weather may even stop the heat pump from functioning as a cooling system at all.
In cases where homeowners wish to cool their homes in freezing weather, they may want to open their windows.
However, when opening windows remains implausible, installing a supplemental heating system can help heat pumps work even in freezing temperatures.