Air source heat pumps are a fantastic way of heating a home as they extract heat from a renewable energy source but depending on the type of heat pump and size of the property, an outside heat pump unit can often look like a commercial air conditioning unit.
Although external heat pump units can be placed around the side of a house out of the way, they can still stick out, and so can an air source heat pump be covered for reasons such as aesthetics?
An outdoor air source heat pump unit cannot be covered. Air source heat pump units rely on large volumes of air flowing them to extract enough heat energy and covering a heat pump can drastically reduce their efficiency.
Our air source heat pump (ASHP) is in an open area down the side of our house. While it’s out of the way, it’s still located a certain distance out from the house for access and maintenance purposes. We can’t cover it and can’t fence it off because it’s located on the footpath from the front to the back of the house.
While you can’t directly cover an air source heat pump, you may still be able to place it in an enclosed location where airflow won’t be compromised.
We discuss more about why you can’t cover an air source heat pump below and what you can do to help reduce the visual impact of using an ASHP to heat your home.
Covering an air source heat pump completely is not safe. The significant reduction in airflow would cause a massive reduction in heating efficiency and can potentially lead to overheating and failed components.
Although great for both energy efficiency and a reduction in carbon emissions, air source heat pumps can often look like commercial air conditioning units and might not look aesthetically pleasing when installed up against the external wall of a home.
Providing a small enclosure for an external air source heat pump unit, or even covering one over completely, may help to blend them into the outside look of a home.
However, doing this could put your ASHP and home at risk, but could ultimately significantly reduce the effectiveness of that heat pump to deliver heat for the house, where indoor temperatures wouldn’t get high, domestic water wouldn’t be hot and electrical energy usage would vastly increase as the heat pump works overtime.
Covering an air source heat pump and reducing airflow would also reduce how cost-effective the installation of the heat pump was in the first place.
We go over below why ASHPs need sufficient airflow to work, how covering would reduce airflow and what other options you can have for hiding an air source heat pump, rather than covering.
An air source heat pump works by extracting heat energy from the air outside and transferring that energy indoors through refrigerant in pipes for use indoors for space heating, and potentially domestic hot water.
They use fans to force air over a series of heatsinked tubes in which refrigerant is flowing through. This refrigerant absorbs the heat energy stored within the outside air.
See our main article on how air source heat pumps work.
As air source heat pumps are designed to work to very low temperatures (where there is still some heat energy stored in the air), they typically need to work harder in colder temperatures in order to extract the same amount of heat by forcing more air through the unit.
Covering an ASHP unit would significantly reduce its ability to extract heat as airflow would be drastically reduced.
An ASHP also isn’t always on. It will start operating when there is a demand for heating or hot water but will turn on and off periodically when required.
As such, you can’t predict when the external heat pump unit will be operating and so they can’t be covered over.
Air source heat pumps are designed to spend their lifetime outdoors and so are equipped to cope with all types of weather, and so don’t need to be covered for weather-specific reasons.
See our article on the space requirements for air source heat pumps for more information.
If you cover your heat pump and it struggles to get enough air, you could be left with a broken ASHP unit and unable to heat your home.
If an outdoor heat pump unit struggles with airflow, it may work overtime to compensate.
This would increase electricity usage, reduce cost-effectiveness and parts may wear out much more quickly. With a cover, heat may become trapped and lead to over-heating of the heat pump.
Covering an ASHP may also void the warranty.
As for other, less technical issues, your covered heat pump may attract rodents and other small animals during the cooler months. Not only will they nest in your unit because you provided shelter for them, but they may also decide to chew on the wiring.
So, it’s best to avoid giving them a place to stay altogether, especially if it comes at the expense of your heat pump.
Moisture can also become trapped under a cover due to reduce airflow.
There can be ways to safely enclose an air source heat pump rather than covering it.
An open enclosure can allow an ASHP to continue to operate efficiently. However, covering the heat pump should be more about protection than aesthetics.
The most important rule of covering or concealing an air pump is to make sure all the sides are open to receive airflow. As discussed above, there are plenty of dangers when enclosing your pump and so it’s important to do it without causing any damage, and allowing it to heat your home effectively.
Space around an ASHP is also important for maintenance and servicing access.
Firstly, ensure that you’re not fully enclosing the pump. It needs room and a constant flow of air to work properly. Any attempt to cover the pump should be restricted to only covering the top or making sure there are plenty of gaps on all sides of the cover.
Small holes may not be enough to ensure that the pump gets enough air. You should make large gaps in your cover that allow unrestricted airflow through the enclosure. This will ensure that your unit keeps working the way it should.
Using only a top cover may not be ideal for looks, but it’ll allow air to reach the sides of your unit. It also ensures that snow and ice don’t find their way into your ASHP when the wind isn’t too strong.
Therefore, consider only covering the top of the air source heat pump to help keep it safe without affecting the airflow to it, should this be allowed by the manufacturer.
See our main article on air source heat pump enclosures for more information.
Air source heat pumps should not be covered where airflow would be reduced.
Reduced airflow can lead to reduced efficiency and less heating for higher cost.
It can be possible to build enclosures for outdoor heat pump units where improving the aesthetics of a heat pump is desired, but where enough space around the unit it also provided so that airflow isn’t compromised.