Air source heat pumps (ASHP) and air conditioners (AC) are common choices for an HVAC system in many households.
According to the 2020 Residential Energy Consumption Survey, two-thirds of US homes use a central heat pump or an AC as the primary home air conditioning system.
So how do heat pumps and ACs compare when considering home comfort?
Air source heat pumps and air conditioning units can both provide cooling for a home, but with the right setup an air source heat pump can also provide heating as well as cooling. However, some heat pump systems may only be able to provide heating and not cooling.
We use our own air source heat pump for heating and domestic hot water only, and not for cooling.
However, as we live in a milder climate, we don’t need whole-house cooling and therefore have two air conditioning units that serve individual rooms.
We discuss in more detail below the main differences between air source heat pumps and air conditioning units, the types of heat pumps and in what scenarios you would choose one over the other, or both.
Air Source Heat Pumps vs. Air Conditioners
An air source heat pump is a cooling and heating system that transfers heat from one space to another; from the inside of a home or building to the outside, or vice versa, depending on the season.
This means that a heat pump can function as an air conditioner (for cooling purposes) during warmer months by removing heat from the air inside a home and expelling it outside, therefore effectively cooling a home by lowering the indoor air temperature.
In heating mode, an ASHP extracts heat energy from the outside air and delivers it indoors to help raise internal air temperatures.
On the other hand, an air conditioner acts only as a cooling system by moving heat and humidity from an enclosed space to the outside.
An air source heat pump can therefore be considered to be a reverse air conditioning unit that acts in the same way an air conditioner does but can also be used for heating purposes as well as cooling.
Both air source heat pumps and air conditioners have indoor and outdoor units that work together to cool your home, or heat in the case of a heat pump.
However, while outdoor units for both air conditioning and heat pump systems can look very similar, the indoor setup can vary between them depending on the type of air source heat pump system installed.
For example, our home is served by an air to water air source heat pump system.
It consists of an external heat pump unit that’s located outside our home and down the side of our house.
The internal apparatus consists of a hot water tank to provide domestic hot water, and underfloor heating and radiators for central heating.
As we have an air to water heat pump system, heat is extracted from air outside for use within a water-based central heating system inside our home.
While it could be possible to use our air source heat pump for cooling, our system isn’t setup for cooling and therefore only provides heating and hot water for our home.
As we live in a milder climate (the UK), the need for cooling may not be as important as other locations. While we don’t need whole-house cooling for our circumstances, we do however have two air conditioning units that serve individual rooms.
One external AC unit is located next to our external heat pump unit and serves the upstairs main bedroom.
The other AC unit is located down the back of our house and serves the kitchen/dining area.
While we have an air to water heat pump system, air to air heat pump systems can be more popular in other locations where cooling can be just as important, or more important, than heating.
With air to air heat pumps, an external heat pump unit works with an internal air space heating setup. This includes the movement of hot air around a home.
Just like air conditioners, heat pumps can also be ducted or ductless.
For ducted systems, existing home ductwork can be used to move heated air around a home using a central air handling unit.
For ductless air to air heat pump systems, a series of air handling units can be placed around a home and can look much like traditional domestic air conditioning units.
These air to air heat pump systems can be more effective for cooling compared to air to water setups (like ours) and so can be more common in warmer climates.
Air handling units can work in much the same way as AC units and blow cooler air by removing heat from the air inside and expelling it outside.
We explain more about air to air and air to water heat pumps here, and ducted and ductless heat pump systems here.
Is An Air Source Heat Pump or Air Conditioner Better?
Using an air source heat pump can be more appropriate in situations where heating is also required alongside cooling, or where whole-house cooling is needed. For cooling one specific room, a single AC unit may prove a more cost-effective solution.
Can A Heat Pump Work As An Air Conditioner?
In the reversed cooling mode, an air source heat pump can work similarly to an air conditioning unit where heat is extracted from the indoor air at the internal air handling unit and the resulting cooler air is blown into the room.
Is An Air Conditioner An Air Source Heat Pump?
Although an air conditioner can provide the same cooling mechanism and effect as an air source heat pump, an air conditioner can’t be considered a heat pump as they can’t be revered to provide internal space heating.
Heat Pump & Air Conditioning Pros & Cons
You can consider these advantages and disadvantages of heat pumps and air conditioners to help decide which of the two would be most suitable for your home:
|Heat Pumps||Air Conditioners|
|Advantages: Does both cooling and heatingIs energy efficientMay qualify for rebate or government tax incentives||Advantages: Typically lower average installation cost External unit can have smaller footprint|
|Disadvantages: Typically higher average installation costNot ideal as a heating system in extreme climates (may need to be paired with a furnace or boiler)Works all year long, has more maintenance requirements, and may have a shorter lifespan)Outdoor unit may be noisier than that of an AC||Disadvantages: Is a cooling-only system (must be paired with a furnace or boiler for heating)May not qualify for tax incentives|
The Working of Heat Pumps and Air Conditioners
Air conditioners and heat pumps have a similarly operating mechanism that cools your home space by removing heat from inside the house and moving it outside.
This process leaves the air inside your home cooler, which is why you experience a temperature drop when the air ventilates throughout the home.
The standard working mechanism of heat pumps and ACs makes the two appliances look similar in cooling, but the two systems have a significant difference when it comes to heating.
The Comparable Cooling Mechanism in ACs and Heat Pumps
ACs and heat pumps remove heat from the air inside your home in these three steps:
- Warm air and moisture from your living space are absorbed into the cooling system by a working liquid known as refrigerant flowing through the indoor coil.
- The absorbed heat travels as gas to the outdoor coil.
- The outdoor coil dissipates the heat in the refrigerant to the outside air and the cycle continues.
The Heating Difference in Heat Pumps and ACs
Since an AC is a cooling-only appliance, a homeowner with an AC will turn off the appliance during the heating season and turn on a furnace or other heater to heat the home.
However, a homeowner with a heat pump can take advantage of a reversing valve in the heat pump’s system to heat their home. Heat pump heating happens in the reverse steps of the cooling process:
- The refrigerant in the heat pump’s outdoor coils absorbs heat from the outdoor air.
- The heated refrigerant moves through a compressor and to the indoor components of the heat pump into the indoor coils.
- The heat is released from the refrigerant and mixes with the cooler air or water in the system to deliver heat to the home via space heating or central heating.
Should I Get a Heat Pump or Air Conditioner?
While knowing the primary similarity and differences between heat pumps and air conditioners is important for homeowners, understanding the differences in cost, energy efficiency, heating ability, and durability can help you make a more informed decision.
You should install a heat pump if you want an appliance for cooling and heating. However, if you live in climates where cold seasons can be extreme, pairing an AC with a furnace or boiler man be more appropriate than using an air source heat pump for both cooling and heating as an ASHP can only work down to a certain outside temperature.
Heat Pump vs. Air Conditioner Cost
Cost is crucial when homeowners decide on a home HVAC system. For both air conditioners and heat pumps, the installation cost can depend on these primary factors:
- Capacity or size – Puts into account your home size in square feet and the AC size in tons, and can vary with climate type.
- The brand – Higher quality brands will likely cost more than those offering basic performance to meet consumer affordability.
- The Seasonal Energy Efficiency Ratio (SEER efficiency rating) – the higher the SEER value, the more efficient your AC or heat pump can be over the season.
- Installation details – Costs can vary depending on whether you are installing a multi-zone system with a single outdoor unit and more indoor units or pairing your heat pump or AC outdoor unit with a single air handler.
Away from these fundamental factors, the cost of installing a heat pump is generally higher than that of an AC.
See our article on how much an air source heat pump can cost to buy, install and run for more information.
However other aspects can make cost differences between air source heat pumps and air conditioners:
Heating and Cooling Functions
A heat pump can both heat and cool, which means you can save the cost of buying a heating system separately by purchasing a dual-purpose heat pump. It may cost you more upfront, but you won’t have to worry about installing and maintaining two separate appliances.
Instead, an AC is a cooling-only appliance. In this case, installing a heat pump may be cheaper than installing both an AC and a furnace. However, in extremely cold climates you may still need to have access to a backup heating system, which can be added cost.
If your home is in a location where winter does not fall to extremely low temperatures, it can be enough to buy a heat pump for both your heating and cooling needs. You won’t need to purchase an additional heating system, which can save on cost.
For example, our air source heat pump works down to -20°C (-4°F) but it’s not able to guarantee to provide heating below this outside air temperature as there’s just too little heat energy within the air to effectively use. ASHP’s typically work down to around this temperature.
As we live in a milder climate (UK) our temperatures don’t reach this low but if you live in a climate that experiences lower temperatures than what a heat pump can work in then you may need to consider the use of an alternative heating system with AC, in additional to, or instead of using an air source heat pump.
Maintenance & Replacement
As heat pumps perform heating and cooling functions and operate almost all year long, they can be more prone to wear and tear.
However, with annual servicing maintenance and maintenance a heat pump can still last many years.
See our article on how long air source heat pumps last for more information.
Government Rebate or Tax Initiatives
Heat pumps may qualify for rebates or tax incentives from the local utility company, state, or federal government due to their energy efficiency. This would mean a reduction in cost for the homeowner.
You can find info about US related policies and incentives in your state on the Database of State Incentives for Renewables & Efficiency (DSIRE) page.
In the UK, the Boiler Upgrade Scheme is providing funding for homeowners with a large sum of money off the cost and installation of air source heat pumps.
If you can get an appliance that qualifies for incentives, you may be able to save money during installation. Air source heat pump installations are more likely to quality for incentives than air conditioning.
Heat Pump vs. Air Conditioner Efficiency
Heat pumps run only on electricity only and are considered an energy-saving alternative capable of delivering three times as much heat as the energy they use.
Since they can transfer heat from the air without converting it from a fuel source, they can be a much more efficient source of heating. According to the US Department of Energy, heat pumps can help reduce your energy use by 50% when compared to furnaces. Air source heat pumps can also absorb humidity better than air conditioners, meaning less energy consumption and better comfort.
See more about air source heat pump efficiency here.
Heat Pump vs. Air Conditioner Noise
Although most modern cooling and heating systems are quieter than those manufactured in the past, they will still produce some noise.
External heat pumps units may make more noise than conventional HVAC systems. As a result, installers recommend placing your outdoor heat pump unit away from patios or bedroom windows where noise can be a nuisance.
See our article on air source heat pump noise for more information.
Air Source Heat Pumps vs Air Conditioners
Both heat pumps and air conditioners have their advantages and disadvantages. Consider your specific needs when comparing the two to decide which one you should go for. If you intend to install a single appliance for both cooling and heating, a heat pump may be the better option.
If your deciding factor is the initial cost, installing an AC can be cheaper but can’t provide heating and so a separate heating system would need to be installed, if not already.
Consider that an air source heat pump can be an effective solution for providing both heating and cooling within one system, but will only typically work down to a certain temperature before heating effectiveness will drop off, and in extreme climates another backup heating system may be necessary.
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