Air source heat pumps have become a more popular option in many homes as carbon footprints are looked to be reduced and traditional means of heating a home using fossil fuels is less relied upon.
While air source heat pumps can be considered to be the best option for heating a home for the foreseeable future thanks to a range of benefits, they also have a number of downsides that have prevented them from being installed in homes more frequently.
Air source heat pumps have a high energy efficiency, can be used with air and water systems for both heating and cooling, and can provide domestic hot water. However, higher initial purchase and installation cost compared to traditional heating systems can be their biggest downside.
Our air source heat pump was installed alongside our new-build home.
We’ve been using this air source heat pump (ASHP) for over 5 years now for both heating and hot water and have come to fully understand its benefits, but also its downsides.
It can come down to a matter of personal preference and your home’s setup when considering installing an air source heat pump. Below, we expand on the pros and cons of getting an air source heat pump for your home.
Air source heat pumps can offer a plethora of positives to your home.
They can be much more efficient compared to other more traditional forms of heating and can potentially provide all three functions of heating, cooling and hot water in one system.
There are two main types of air source heat pump system and the type used can depend on your preferences, your home’s existing setup and the installer’s recommendations.
The two types of ASHP include:
- Air to water heat pumps
- Air to air heat pumps
Air to water heat pumps (like the one we own and use) extract heat from outside air for use within a water system inside a home, for example central heating that utilizes radiators and/or underfloor heating.
An air to water heat pump can be retrofitted into a home that uses such an existing heating system, such as with a gas boiler.
Air to air heat pumps provide space heating by supplying warm air through a home. They can be implemented into homes that utilize existing vents, but isn’t required.
See our article comparing air to air and air to water heat pumps for more information.
Air source heat pumps that utilize a water heater can also potentially provide both water heating and air conditioning.
Depending on the type of air source heat pump you install, you can use it to both heat water and condition air in your home. This is two jobs in one, replacing the need for other heating and cooling options.
Whatever your existing setup, and installer will be able to choose the right type of air source heat pump for your home.
Air source heat pumps can work as a cooling and heating system for your home.
Depending on where you live, this could be a significant advantage over using more than one system for heating and cooling, as there can be significant changes in weather between winter and summer.
Air source heat pumps can be considered primarily as heating appliances, but many can be setup to also provide cooling instead of heating if required.
An ASHP can provide cooling by extracting heat energy from inside a home and expelling it outside, rather than extracting heat from outside and providing it indoors when in heating mode.
Our air source heat pump is able to provide cooling with the right setup. The image below shows the operating temperatures in which our heat pump is able to provide cooling.
We don’t personally use our ASHP for cooling and our local climate doesn’t demand the need for it. Instead, we have a couple of air conditioning units that serve specific rooms.
See our article on air source heat pump cooling for more information.
One of the more significant selling points for air source heat pumps can be their high energy efficiency.
They can be a great option for those worried about their carbon footprint. Air source heat pumps can:
- Reduce greenhouse gas emissions
- Use less energy
- Reduce running costs for heating and cooling
For the energy your home consumes (and that you are paying for) to power an air source heat pump unit, you can get double or triple the amount of heat energy back.
This efficiency is called the Coefficient of Performance (or COP for short), and it measures the energy output compared to the energy input. Most air-source heat pumps are in the two to three coefficient range.
Other values that identify the efficiency of a heat pump can be seen through the EER (Energy Efficiency Ratio) and SEER (Seasonal Energy Efficiency Ratio).
However, this efficiency can be more or less, depending on factors such as outdoor temperatures, desired indoor temperatures, and the efficiency rating capabilities of the heat pump.
Our ASHP can reach a COP of over 4 for the most ideal scenario, meaning that for every 1 unit of electrical energy consumed, over 4 units of heat energy can be provided.
This is in comparison to more conventional forms of heating such as gas boilers, which can be less than 100% efficient.
See our main article on air source heat pump efficiency for more information.
4. ASHPs Are Electric Only
Air source heat pumps are electrical appliances and therefore only require an electricity supply in order to work.
For example, our ASHP takes electrical power from inside the house.
You therefore won’t need any other forms of traditional heating fuels such as gas and oil to run an air source heat pump.
See our guide on the electrical requirements for air source heat pumps.
Air source heat pumps are already known for being a reliable source of clean energy, but they’re not all the way “green” certified. They still require electricity to function, which can make them a non-renewable energy source, even though heat energy stored naturally within the outside air can be considered a renewable source of energy.
An air source heat pump can be connected up to solar panels, helping to make it a completely green energy source.
Countries and states have offered incentives to install air source heat pumps, such financial incentives.
Air source heat pumps can be much more energy efficient than furnaces and boilers and using them can help reduce a person’s carbon footprint. For this reason, there are many federal and state programs that will reward homeowners for installing them.
These incentives usually look like:
- Tax credits
- Discounts on the installation
An installer will be able to provide info of any incentives for installing an air source heat pump in your area.
7. Can Act As Filters And Dehumidifiers
Humidity can make your home feel stuffy and uncomfortable, and moisture in the air can be a breeding ground for bacteria.
Humidity causes mold, mildew, and musty smells, and mildew, and dust can be triggering for people with asthma.
An air to air heat pump can filter the air before it enters your home for space heating, but such filters should be cleaned and/or changed regularly as part of the ongoing maintenance of an air source heat pump system.
8. ASHPs Can Provide Domestic Hot Water
Air to water heat pumps can be used to provide hot water for ahome for taps, showers etc. alongside being used for space heating.
This allows an air source heat pump to deliver all of the heating and hot water needs for a home, without the need for a separate system for hot water.
However, air source heat pumps work differently to traditional heating systems and can’t provide the same on-demand hot water that these other systems can typically provide.
Heat pumps extract and deliver heat more slowly over time and so they must operate for longer periods of time to deliver the same level of heat.
As such, an ASHP will need to be used alongside a hot water storage tank if also being used for domestic hot water purposes. See our article on using a hot water tank with an air source heat pump.
A hot water tank will allow the water to be stored while the heat pump delivers the heat to warm the water up over time. Such tanks also typically have immersion heaters for when demand outweighs the supply of hot water.
We have a hot water tank that works with our air source heat pump to provide hot water for our home, and we’ve never had an issue with hot water running out.
Hot water supply can be used air to water heat pumps and the use of an air to air heat pump system will still require a separate system for providing hot water.
Our article on using an air source heat pump to provide hot water covers this in more detail.
9. Can Work At Very Low Temperatures
Air source heat pumps can work in a range of climates and can continue to operate and generate heat for a home even at very cold, negative temperatures.
At low temperatures there can still be enough heat energy within the air for air source heat pumps to extract and use.
Air source heat pumps can typically work down to around –20°C (-4°F).
Temperatures in our climate never reach this low and so we’ve never had any issues with our heat pump not being able to supply our home with heating and hot water through winter.
However, output temperatures from an air source heat pump can lower as outdoor temperatures reach the minimum temperatures within the operating range of a heat pump, and so in extreme climates an ASHP may have to be used alongside a traditional heating system.
See our article on how air source heat pumps can work in winter for more information.
10. ASHPs Can Last
Air source heat pumps can last up to 20 years with low demand and the right maintenance and servicing.
Our heat pump has been working for over 5+ years now with no problems at all, but was installed by a professional and has been serviced every year by qualified personnel.
Our article on how long air source heat pumps last provides more information.
11. Minimal Maintenance
Much like other more traditional forms of heating system, a yearly service is essential to help prevent unexpected issues from occurring, and general cleaning of a heat pump should be undertaken in between services.
We periodically clean out leaves and other debris from our ASHP to help ensure that it’s always operating as effectively as possible.
Other than periodic cleaning and yearly servicing, an air source heat pump can require minimal maintenance.
We go over the downsides of installing and owning an ASHP below, using our own heat pump as an example.
12. Requires A Suitable Installation Location
Air source heat pumps can be relatively large appliances, depending on factors such as the size of house.
The external heat pump unit will also need to be installed in a suitable location outside the home for it to work.
Installation requirements such as proximity to the house, taking into account wind and sun, ensuring adequate airflow, and proximity to neighboring properties, among other things, will all need to be considered prior to installation.
Some external space will therefore be required in order to have an ASHP installed, but an installer will be able to find the right location for one around your home.
Air source heat pump units can be costly to purchase and install.
This upfront cost will need to be taken as a hit in order to have an ASHP installed and enjoy their benefits.
While our heat pump was installed when the house was built, the cost of purchase and installation of the overall heat pump system was no doubt reflected in the price of the house.
Depending on the setup of your home, you may also need a lot of work done to provide the right air source heat pump system.
If you retrofit your current heating system with a new air source heat pump, certain indoor apparatus may also need to be upgraded or replaced altogether. Though they can run using old ductwork from a boiler or furnace, additional work may be required to bring a home up to a suitable standard for use with an ASHP.
For example, sufficiently large radiators may be required and if a home has older radiators with less than adequate surface area then they may need to be upgraded.
However, it can be the perfect opportunity to install air source heat pumps if you build a new home or do an extensive renovation. You can begin the process early enough that design plans don’t need to be re-adapted for other factors.
There are also the installation costs from the installer. Getting a few quotes from local installers will give you an idea of the upfront costs required in having an air source heat pump installed.
See our article on how much an air source heat pump typically costs.
14. Lower Heat Output
Air source heat pumps rely on electricity as the power source and extract heat from outside air; unlike traditional heating systems which can generate heat through the combustion of fuel.
As a result, AHPs can’t provide the same instantaneous heat as other conventional heating systems, and the heat that is generated can be provided at lower temperatures.
This means that air source heat pumps will need to run for longer periods of time to get the same desired indoor temperatures, but an upside of this is that temperatures can remain more consistent compared to intense heat from other traditional heating systems.
With the right internal setup, an air source heat pump will still be able to heat a home effectively, just in a different way to the more traditional heating systems do.
15. ASHPs Can Be Noisy
Air source heat pumps work by extracting heat energy from the outside air. To achieve this, they use fans to force air through a series of coils in which refrigerant is flowing through. This refrigerant captures the heat and is sent to be used indoors.
Air source heat pumps can be completely silent when not operating (ASHPs don’t have to be running all the time) but can be relatively noisy when they’re on.
When demand increases for heating, cooling or hot water, a heat pump can need to work harder, and this can mean louder fan noise.
Heat pumps aren’t too noisy unless your close, but noise still needs to be considered (for neighbors as well) and so they should ideally be located out the way, such as down the side of a house.
To find out more about noise from air source heat pumps and a video showcasing the noise from our own heat pump see our other article on air source heat pump noise here.
16. Unsuitable For Extreme Climates
Air source heat pumps will only be able to work down to certain temperatures, with the minimum operating temperature dependent on the model of heat pump.
At very low or very high outside air temperatures, an air source heat pump may not be able to provide guaranteed heating or cooling and so in extreme climates a heat pump may need to be paired with another appliance such as a boiler as part of a hybrid heat pump system to ensure that there’s no downtime.
17. Less Efficient At Lower Temperatures
While still effective at low outdoor temperatures, an air source heat pump can produce lower temperature outputs at these lower outdoor temperatures.
For example, the graph below shows how the temperature output from our air source heat pump lowers as outdoor temperatures fall to the minimum outdoor air operating temperature of 20°C (-4°F).
As a result, an ASHP may need to run for longer for indoor temperatures to reach the same desired levels when at the lower outdoor temperature limits, but this lower heat output can still be enough to effectively heat a home.
18. Require Electricity To Work
While requiring only electricity in order to work can be a good thing for air source heat pumps in terms of emissions, a heat pump won’t be able to operate during a power cut as they’re still electrical appliances.
19. Running Costs May Not Be Lower
Depending on factors such as local electricity costs, efficiency of a heat pump and demand for heating, the running costs may not necessarily be currently lower than other forms of heating system.
However, as fuels such as gas and oil increase in energy price and are phased out, over time an air source heat pump may cost much less to run compared to these more traditional forms of heating systems.
An installer will be able to go over the whole life costs of running and air source heat pump with you.
In our other article on whether air source heat pumps are expensive to run we go over how much our electricity bill is for reference.
20. Must Be Thought Of As A Long Term Investment
For an air source heat pump to be worth it, they must be considered as a long-term investment, rather than short-term one.
With typically higher purchase and installation costs, the benefits of an air source heat pump may not be recuperated in the short term and so when looking to install a heat pump the financial return should be considered all the way up to the life expectancy of the heat pump.
Thankfully, the typically long life, low maintenance and ability to get electricity from a renewable energy source for an ASHP can mean that they can be very good long-term investments.
Our article on whether air source heat pumps are cost effective covers this topic in more detail.
21. A Home Needs To Be Well Insulated
As air source heat pumps deliver heat more slowly compared to traditional heating systems, a home needs to be well insulated to keep the heat in long enough for indoors temperatures to rise sufficiently.
When installing an air source heat pump in an older home, an installer may recommend a home to be better insulated to make the most of an ASHP, which can increase upfront costs.
22. Sufficient Indoor Heating Apparatus Is Required
Similarly to poor insulation leading to ineffective heating, if the existing internal heating apparatus isn’t sufficient for use with an air source heat pump then it may not be able to effectively heat a home.
Air source heat pumps will need to be used with right heating equipment to ensure that the lower temperature heat is released into a home as efficiently as possible.
Our house uses underfloor heating on the lower floor and radiators on the upper floor to achieve this.
Again, if an existing heating system needs to be upgraded or even fully replaced then this can also increase installation costs.
23. Not The Most Aesthetically Pleasing
The external heat pump unit of an air source heat pump system can look much like a commercial air conditioning unit.
While still such a great appliance for any home, air source heat pumps aren’t always the most aesthetically pleasing to look at and are therefore typically installed down the sides of a house and out of the main views.
Pros & Cons Of Air Source Heat Pumps
There are many benefits to installing an air source heat pump, but there are also some cons. Air source heat pumps are more energy-efficient and do more than furnaces and boilers. However, a traditional boiler or furnace may be less expensive to install.
Reach out to an expert if you’re curious about air source heat pumps for your space, and don’t forget to look up your local incentive programs to see if you can earn rewards for installing an air source heat pump.