While air source heat pumps don’t require the same amount of land take as ground source heat pumps, both the indoor and outdoor components of an air source heat pump system still need a certain amount of space for installation, efficient operation, and maintenance.
The exact space requirements for air source heat pumps can differ between installations where different sizes and manufacturers are used, but enough space must be provided around outdoor heat pump units to allow for sufficient airflow and for maintenance and servicing access.
Our own air source heat pump is installed on the ground off the side of our house. It’s located in an area that’s out of direct sunlight and high winds but still plenty of space for air circulation.
It’s also installed away from the external wall of the house to provide sufficient clearance for airflow, access to the rear of the unit and for the refrigerant pipes that carry the heat indoors.
In this article we’ll look at the space requirements for air source heat pumps in more detail, including exactly how much space we needed to accommodate for both the indoor and outdoor apparatus for our heat pump heating and hot water system.
Understanding the spaced required for an air source heat pump system can be one of the factors that affects where to install a heat pump in the first place.
We’ve covered where to install an air source heat pump in another article and look at factors such as locating an outdoor heat pump away from high winds and direct sunlight.
When a location for the outdoor unit of an air source heat pump (ASHP) system is chosen, sufficient space needs to be provided around the unit for reasons such as:
- Sufficient air circulation
- Access around the unit for maintenance and servicing
- Space for any pipes, ducts or power cables
- Noise & vibration considerations
Our ASHP is located on the side of our home adjacent to the internal garage wall.
This location provides shelter away from direct sunlight and high wind but there’s plenty of space around the unit for air circulation.
It’s also mounted directly onto the ground in line with the manufacturer’s requirements, although it also may be possible to mount an air source heat pump on a wall if allowed.
This external heat pump unit is placed a small distance away from the external wall of the house.
This allows for the pipework that holds the refrigerant and carries the heat energy indoors to be tucked away behind the heat pump.
Providing this amount of space behind the unit also ensures that airflow through the heat pump from the back and through the front isn’t compromised.
There’s also space for an engineer to access the back of the heat pump should it be required.
See our main article on air source heat pump installation requirements for more information.
Manufacturer Guidelines For Space Requirements
The main factor that dictates the space requirements for any air source heat pump will be the guidelines set out by manufacturer for a specific unit.
An installer may also need to provide other space around heat pumps, depending on any local and/or national guidelines and any installation-specific requirements.
The manual for our ASHP outlines the manufacturer’s guidelines for the space requirements around our heat pump.
As there can be different situations for each individual installation, our manual gives a range of situations and their space requirements.
As shown above, there are requirements to have enough clearance space around our air source heat pump:
- Behind the unit
- In front
- To the sides
- In front of the unit from any overhang
These are the space requirements for our specific model of air source heat pump and the space requirements for any other model can differ and must be adhered to.
However, this can be used as a guideline if you’re looking to understand how much space is generally required around the external unit of an ASHP system.
Air Source Heat Pump Indoor Plant Space Requirements
Depending on the type of air source heat pump (air to air or air to water), certain apparatus will be required for providing the heating, cooling or domestic hot water indoors.
While air to air heat pumps can require ducts, pipes and air-handlers, air to water heat pumps (like ours) can require space for radiators, underfloor heating, a water heater storage tank and any other associated heating or hot water equipment.
Space must be provided for the pipes travelling between the indoor and outdoor components of an air source heat pump system.
For our house, pipes connect from the external heat pump unit through the garage and into our utility room cupboard.
It’s within this cupboard where all of our internal heating and hot water apparatus is located (apart from thermostats, underfloor heating, radiators and interconnecting pipes).
While the internal components of an ASHP system won’t require the same level of space requirements around them as the outside unit, a certain amount of space is still required.
An installer will be able to identify where any internal apparatus can be located in your home.
See our article comparing air to air and air to water heat pumps for more information.
Space Requirements For Different Air Source Heat Pump Types
There are essentially two types of air to air source heat pumps: ductless mini-split systems and central split type units (with or without a furnace). When choosing between these categories, you’ll want to consider exactly how much space you have available.
You don’t want to purchase something too big, nor do you want something so small it doesn’t work efficiently. First, you should determine where the heating and cooling equipment can be mounted in your home or office.
Here are some general guidelines to help you determine how much space is required for an air source heat pump:
- Split-system heat pump: This type of heat pump requires about 60 square feet (5.57 square meters) of space.
- Ductless mini-split heat pump: This equipment needs about 30 square feet (2.78 square meters) of space.
If you think you have adequate room for an air source heat pump, approximate the size of a typical heat pump using a tape measure. It’s always better to have space left over than not enough.
Furthermore, if there’s still plenty of space available after installing your HVAC, consider adding some nice extras like a smart touch screen control panel.
There are three main components with split systems:
- An outdoor unit
- An evaporator coil
- A furnace or blower motor
The outdoor unit will have two pipes leading into it – one for condensate removal (the liquid left over from the cooling process) and one for the power supply.
Since these pumps are rather large, they should be installed in high-traffic areas where their noise won’t bother anyone too much.
If this isn’t possible, you should go with two smaller units instead of one large unit. In general, split system heat pumps require at least 60 square feet (5.57 square meters) of space to operate properly at all times.
To function correctly, an air source heat pumps requires a specific amount of cubic feet per minute (CFM) for proper ventilation.
If you have any obstructions, such as furniture or extra appliances in the room, you need to increase the CFM by about 10%. Check whether your room can fit this type of equipment before purchasing and installing it.
The space requirements for a typical air source heat pump are a little more strict than those of a traditional heater because of the extra components that must go into its installation.
Ductless split heat pumps are a popular choice for homeowners and businesses that don’t have the necessary installation requirements for their HVAC system. These units can be smaller than traditional heat pumps because they lack a compressor unit. These types of heat pumps must be installed in a space at least 2 feet (0.60 m) high, 2 feet (0.60 m) wide, and 4 feet (1.21 m) long.
This type of heater also requires a minimum amount of 5 cubic feet per minute (8.49 cubic meters per hour) for proper ventilation.
Ductless split heat pumps also require less ventilation, but there should be no obstructions in the room. Otherwise, you’ll need to increase your CFM by 10%.
To give you an idea of how much airflow is required for your air source heat pump installation, one CFM equals 450 cubic inches (7374.18 cubic centimeters) of air per minute. This means that your HVAC system will produce about one cubic foot of air every minute.
Air source heat pumps are great for various purposes, but you must ensure your space is adequately ventilated and stays within the recommended airflow.
The International Residential Code (IRC) states that no concealed spaces should be used as a return air location, such as storage cabinets, closets, and pantries. If you place your heater inside one of those spaces, you’ll need to increase your minimum ventilation requirements by 10%.
Also, ensure that the outdoor unit of your air source heat pump is at least about 3 ft (1 m) away from any other objects. Avoid installing the ASHP in narrow spaces. The outdoor unit isn’t enormous, but it’s large enough to obstruct the way.
While an air source heat pump doesn’t take up too much space, you’ll want to make sure you have enough room near an outside wall or window for optimal airflow. You should also avoid using any concealed spaces as a return air location for air to air heat pumps.
Contact your local HVAC technician if you have any questions about your specific unit or need help finding the right spot for it. They’ll be able to help you figure out the best place to install your new air source heat pump, taking into space requirements around the outdoor units, and answer any other questions you may have.