Find the best installation location for a heat pump: tips from the expert

Heat pumps can be sited in various locations, and there are different factors to consider for each. This is an important decision, as the installation location can affect a heat pump's efficiency and performance. Read on to discover valuable information and helpful tips about which locations work for which heat pumps and what to consider when making your choice. We have also included frequently asked questions on installation locations answered exclusively by Viessmann heat pump expert Egbert Tippelt.

The different installation options for heat pumps 

Heat pumps work by drawing ambient heat from the air, ground or water and then raising it to a higher temperature level so that it can be used to provide heating and hot water in buildings. The heat sources must be easily accessible in order for heat pumps to efficiently absorb the ambient heat. There are three installation options:

  • Indoor installation: The heat pump comes in a monoblock design and is installed within the residential building.
  • Outdoor installation: The heat pump comes in a monoblock design and is installed outside the building.
  • Split installation: The heat pump consists of two components – an indoor unit for inside and an outdoor unit for outside the building envelope.

Consider the type of heat pump when choosing the most suitable installation location

Which heat pumps should you install where? To find the right installation location, you need to consider the type of heat pump and the local conditions. It is worth consulting a heating contractor to determine the best location and the right heat pump for a building or property.

Brine/water heat pumps installed in basements

These heat pumps draw thermal energy from the ground – for example via geothermal probes or surface collectors. In most cases, complex structural measures are needed for probes and collectors, so it is best to get advice from a specialist contractor. The geothermal heat is transported via connection pipes from the geothermal probes or surface collectors to the indoor heat pump unit, which is responsible for transferring the extracted heat to the building's heating system. The installation of the indoor unit is less complex as it is not dependent on geological conditions. Ideally, the indoor unit should be installed in a basement or mechanical room to keep the pipe runs between the heat pump and energy source as short as possible. For trouble-free operation, the location should be well ventilated and the floor capable of bearing the relevant load.

Flexible location options for air source heat pumps

These heat pumps extract thermal energy from the ambient air. Since they can be installed as both monoblock and split units, there are several options when choosing an installation location. The best choice in each situation should be assessed on a case-by-case basis. Both alternatives will work very efficiently in new and older buildings when sized correctly.

A detailed look at the individual installation options

The different installation sites and their pros and cons are explained in more detail in the following comparison. Since brine/water heat pumps are almost always monoblock units, ideally designed to be located in a basement or mechanical room, the information in the following sections is applicable to air source heat pumps.

Monoblock heat pump installed indoors 

In this monoblock heat pump setup, all refrigeration components are located inside the building. There has to be sufficient space for this (approx. 2 x 2 metres). In addition, air ducts must be installed for the supply and discharge of outdoor air. In a new building, this can be easily allowed for at the design stage.

Location and position: Ideally, heat pumps should be sited in a well-ventilated room, on a solid, level floor with sufficient load bearing capacity. It is worth allowing adequate clearance between the heat pump and wall openings so that the air ducts are spaced out. Corner positioning is particularly advantageous. This reduces the risk of a thermal short circuit and ensures the heat pump can operate efficiently.

Please note: Too small a distance between the air ducts can lead to a thermal short circuit. This occurs when a heat pump immediately draws cooled air back in that had just been transferred outside after giving off its heat.

  • Comparatively easy and quick installation thanks to compact design
  • Low maintenance and good protection from the elements
  • Shorter pipe run between heat generator and consumers
  • Less flexible siting due to size and weight
  • Requires sufficient space in the building
Structural measures
  • Requires adequately spaced wall openings for air ducts to draw in and discharge air
  • Additional installation of a drain for condensate generated

Monoblock heat pump installed outdoors 

In the case of a heat pump installed outdoors, all components involved in the refrigerant circuit are housed within one unit that is located outside the building envelope and is therefore in direct contact with the heat source (air). Outdoor units can be flexibly positioned and are also suitable for retrofitting in existing buildings. Heating energy is generated in the monoblock and then transported into the building via well-insulated pipes.

Location and position: It is important to have a stable base at the installation site for the heat pump to stand on, ideally a firm concrete foundation or plinth. To avoid long transport routes and prevent the DHW cooling down, it is advisable to choose a location close to the house wall. However, the following locations are also an option:

  • on a roof
  • on a garage
  • under a carport

Positioning heat pumps in a location that is sheltered from the wind helps to avoid thermal short circuits. Furthermore, there must be sufficient space around the fan opening to allow an adequate supply of air. 

  • Flexible siting, easy retrofitting and maintenance
  • Short pipe runs from the energy source to the consumer
  • Less space required and lower sound emissions in the living space
  • Comparatively somewhat louder in operation
  • Generally somewhat higher upfront costs
  • Detracts from the aesthetic appeal of the property
  • Exposed to the elements all year round
Structural measures
  • Two holes must be drilled in the house wall for insulated pipework

Split heat pump installation

Split heat pumps have two units – one located outdoors and one indoors. The indoor unit contains, among other things, the condenser and circulation pump. It is therefore quiet compared to the outdoor unit, which holds the noise-emitting components, such as the fan, evaporator and compressor. Minimal drilling in the wall is required to link the two units together. 

Location and position: Split heat pumps have units located both outdoors and indoors. The indoor unit is quite compact and can therefore be installed in a number of places in the home. Generally speaking, the basement is a particularly good location. The outdoor unit is sited outside the building and should be placed on a stable foundation or platform in a location that is sheltered from the wind, similar to a monoblock heat pump installed outdoors. 


  • Flexible siting of the outdoor unit
  • Modest space requirement of the compact indoor unit  
  • Sensitive components (in the indoor unit) are protected from the elements
  • Cooling option through reversible operation
  • More effort required for installation and maintenance work, including regular refrigerant inspection
Structural measures
  • Small holes drilled in the wall for refrigerant lines

Finding the right place to install a heat pump 

Where a heat pump is installed can affect its efficiency, service life and operation. A well-chosen location enables optimal use of ambient heat and helps minimise energy consumption. Careful planning and expert advice are the be-all and end-all when deciding where to site a heat pump. This includes taking into account the building characteristics, available space and individual preferences. It is important to consider the following factors at the planning stage.

Minimum clearances

Monoblock and split outdoor units must be sited at least three metres away from other buildings, pathways and patios. Although sound emissions are low thanks to advanced technologies such as Viessmann Super Silent, a certain amount of noise is still generated when outdoor air is drawn in. Ideally, heat pumps should therefore be located a sufficient distance away from surrounding properties so that residents and neighbours are not disturbed by any noise coming from the heat pump. In addition, a very cold air flow is produced when the air is blown out and this can be unpleasant to the touch.

Freestanding installation for air circulation and ventilation 

Air source heat pumps draw in air on one side of the unit and blow it out on the other. There must be an unobstructed air flow around the heat pump at the installation location. The unit should be positioned at least 20 centimetres away from, for example, the house wall. Good air circulation ensures undisturbed heat transfer and prevents the unit from overheating.

Good accessibility for installation, maintenance and repairs

Due to the size and weight of heat pumps, local conditions are already an important consideration when choosing the installation location. Narrow basement steps in older buildings, for example, can cause difficulties. A heat pump should be easily accessible in the chosen location so that installation, repair and maintenance work can be carried out without any major issues.

Frequently asked questions about installation locations for heat pumps

The outdoor unit of a split heat pump should be sited at least 25  centimetres from the wall to allow good air circulation around the heat pump.

  It is best to check the building regulations for your area.

We recommend locating units three metres from pathways, as cold air blown out by heat pumps can cause ice to form.

You should leave a distance of one metre from the lower edge of the heat pump. This is known as the safety zone around the heat pump and is intended to prevent refrigerant leaking into the building.

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