Air Source Heat Pump Maintenance Requirements

Air source heat pumps can be a very efficient way to heat or cool a home, and as part of the overall system require an external air source heat pump unit to extract heat from outside air, as well as associated internal heating, cooling and hot water apparatus.

Air source heat pump units are electrical appliances and use fans to force air over a series of coils carrying refrigerant to extract heat. Heat pump units can also house the compressor that helps to maximize the heat gained.

As with any mechanical and electrical system, air source heat pumps require periodic maintenance to help keep them running smoothly and to last for as long as possible.

Air source heat pumps will require maintenance and servicing in line with the manufacturer’s guidelines, typically annually, and may require further user maintenance in between services. Maintenance requirements can include checking system settings and operation, and replacing parts as needed.

We have our own air source heat pump serviced every year and the maintenance undertaken follows the manufacturer’s guidelines for our heat pump.

We undertake seasonal user maintenance for our heat pump and have it serviced every year

In this article we discuss more about the maintenance requirements of an air source heat pump, how often they should be serviced, and the benefits of regular maintenance.

What Maintenance Does An Air Source Heat Pump Need?

Air source heat pump (ASHP) units have a range of internal components that all need to be operating effectively for the overall heat pump system to be working as efficiently as possible.

An air source heat pump typically doesn’t need too much regular maintenance and a yearly service by a qualified professional can suffice. Further general cleaning and removal of debris may be required every season by the user in between services.

The main maintenance requirements that an air source heat pump will need can include:

  • Checking overall system functionality and the settings.
  • Checking and/or topping up refrigerant levels, as well as checking for leaks and checking ant-freeze levels.
  • Checking external heat pump unit and anti-vibration mounts.
  • General cleaning and debris removal for external heat pump unit, in particular around the coils.
  • Checking motors for wear.
  • Checking electrical connections.
  • Checking any indoor heating apparatus such as expansion vessels, buffer tanks, domestic hot water tanks, control panels and any other associated equipment.
  • Cleaning and/or replacing any filters.
  • Removal of any overgrown vegetation around an external heat pump unit.

Each air source heat pump will typically come with a service manual.

An air source heat pump will also typically have a service panel that can be removed to access all the main electrical and mechanical components inside.

Access to our heat pump’s internal components is on the right side of the unit

During an annual service, a technician will remove this access panel and check the unit over.

One important thing to note is that any electrical supply to a heat pump must always be isolated before any work is carried out. The service manual for our ASHP shows the following notice:

Our heat pump has an electrical isolation switch located on the wall next it so that power to the unit can be isolated to allow any maintenance work to proceed.

The power isolation switch for our heat pump, allowing safe access to the unit for maintenance and servicing

Overall System Operation & Settings

The main components of an air source heat pump system include the external air source heat pump unit and the internal heating and/or hot water apparatus.

Our heat pump is located down the side of our house, with space provided around the unit for access for maintenance and servicing.

Air Source Heat Pump
Our external air source heat pump unit

Pipes connect this external unit to a cupboard inside our home where all our main internal heating and hot water apparatus is located.

Air Source Heat Pump Hot Water Tank
The main internal apparatus for our air source heat pump heating and hot water system

A control panel outside this cupboard is where all our heating and hot water settings can be operated from.

Air Source Heat Pump Water Heater Control Panel
The main control panel for our air source heat pump system

As part of maintenance a technician will have a look through these settings to ensure everything looks right and in working order.

In between services, a technician may ask you to keep an eye on any apparatus part of the heat pump system that may indicate an issue, such as a pressure gauge for a central heating system.

A tank and pressure gauge for our central heating system

Fluid Levels & Pipe Leaks

An air source heat pump system works by extract heat at the outdoor heat pump unit and moving that heat inside to the indoor heating apparatus via refrigerant within pipes.

The whole section of pipes should be checked for leaks to ensure that refrigerant levels don’t go down over time.

Pipes travel from the back of our ASHP unit through our internal garage and to the indoor apparatus.

Air Source Heat Pump Back
The pipes out the back of our heat pump

Connections at each end of the pipes should also be checked to ensure that they’re secure.

Air Source Heat Pump Pipe
The pipe connections to the heat pump

A technician will top up refrigerant levels, or replace the refrigerant altogether, as and when required.

Check External Heat Pump Unit

The external heat pump unit of an overall air source heat pump system should be checked over as part of annual maintenance for any issues relating to the unit itself.

This can include its connection to the ground (or to a wall if wall-mounted) and the effectiveness of any anti-vibration mounts.

Our heat pump is a dual fan unit that’s bolted down to a concrete slab on the ground.

It sits on anti-vibration mounts to help reduce vibration and noise while in operation.

Air Source Heat Pump Base
The connection of our heat pump to the ground with anti-vibration mounts

Any access panels should also be securely fastened to the unit to help prevent damage to any internal components.

General Cleaning Of Heat Pump

An air source heat pump consists of two main parts: an outdoor and indoor unit. The outdoor unit contains the compressor and outdoor coil, while the indoor unit consists of the indoor coil and expansion valve.

Since the outdoor unit is exposed to the elements, it can be important to clean it periodically.

Over time, leaves, dirt, and debris can build up on the coils, reducing the unit’s efficiency.

The most important areas to focus on when keeping a heat pump free of dirt and debris should be the coils where heat is captured as air flows through.

For example, we periodically clean off cobwebs and other debris from the coils on the back of our heat pump, and also wash it down.

A user should clean a heat pump when needed in between services

We also remove leaves stuck in the heat pump when needed.

Air Source Heat Pump Side
Debris such as leaves can affect airflow

You should clean the outdoor unit at least once a year and more often if it’s located in a particularly dusty or dirty area. Cleaning an external heat pump unit seasonally can help to keep on top of build-up of dirt and debris.

Checking Motors

The fan(s) in an air source heat pump are driven by electric motors and so it can be important to periodically check these motors for any wear, as any problems arising from the fans can affect airflow and therefore heating performance.

The fans inside our heat pump

Lubricating the motors can also help to help keep the system running quietly.

Inspect Electrical Connections

The electrical connections in an air source heat pump should be checked and tightened for continued effective performance.

This can be done by a technician as part of an annual service, and can include:

  • The main power supply
  • The circuit breakers
  • The wiring between the indoor and outdoor units
  • The terminals
Air Source Heat Pump Power Supply
Power supply into our ASHP

Checking Indoor Apparatus

While an external air source heat pump unit can be the focus of any maintenance work, the internal heating and/or hot water apparatus can be just as important.

All our main internal ASHP equipment is located in one cupboard, and the range of components that should be inspected as part of any maintenance regime can include:

  • Expansion vessel
  • Buffer tank
  • Air handling unit
  • Hot water tank
  • Radiators and underfloor heating
  • Any associated pipework and apparatus

As we have an air to water heat pump system rather than an air to air system (we outline the differences between air to water and air to air heat pumps here), our heat pump works with a central heating system.

Our indoor apparatus therefore consists of water-based apparatus such as tanks, radiators, and underfloor heating.

Tanks inside our home for central heating and hot water

It may be possible to check the health of central heating system by looking at pressure gauges.

For air to air systems, any air handling units can be inspected as part of maintenance.


A filter on an air source heat pump system can play critical role in keeping dust, dirt, and other airborne particles from clogging up the system. If left, airflow through a heat pump can be compromised and may need to work harder to maintain the desired indoor temperatures.

Scheduling Annual Maintenance

Maintenance to be undertaken by a qualified professional should be undertaken in line with the manufacturer’s guidelines for the heat pump, which is typically recommended to be every year.

While the above can give you an idea of the maintenance requirements of an air source heat pump, a professional will be required to undertake most of the maintenance.

Annual maintenance by a registered professional may also be required to keep the warranty of a heat pump valid.

Regular maintenance will help prolong your heat pump’s lifespan and keep it running smoothly for years to come.

This video covers more about maintenance requirements of air source heat pumps:

How Often Should an Air Source Heat Pump Be Serviced?

Air source heat pumps should be serviced at least once a year. However, if you live in an area with more extreme weather conditions, you may need to have the system serviced more regularly.

If a heat pump stops working properly, you should call a professional as soon as possible. The sooner the problem is fixed, the less damage it’s likely to cause.

See our article on air source heat pump servicing for more information.

Benefits Of Regular Maintenance For An Air Source Heat Pump

The benefits of regular maintenance for an air source heat pump can include reduced energy bills, fewer repair costs, prolonged lifespan, and improved performance.

Maintenance by a professional in line with the manufacturer’s guidelines, and more regular user maintenance as required, will be important for any air source heat pump system.

By following the maintenance requirements of a heat pump, you can help it to keep operating as effectively and efficiently as possible.

Not following a periodic maintenance regime could lead to increased wear and higher repair bills further down the road, and even a reduced life expectancy of a heat pump.

Further Reading

Parts Of An Air Source Heat Pump Explained

How An Air Source Heat Pump Works

Air Source Heat Pump Installation Requirements

Air Source Heat Pump Efficiency Explained

How Much An Air Source Heat Pump Costs To Buy, Install & Run