Air Source Heat Pumps

Five Top Tips to help look after your Air Source Heat Pump

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Five Top Tips to help look after your Air Source Heat Pump

Just like any other heating appliance, air source heat pumps need to be correctly maintained to help the unit and the heating system operate as efficiently and effectively as possible. We have selected five useful pointers for looking after an air source heat pump so if your home heating is delivered by a Grant heat pump, please read on.

In summary...

  1. Keep the air inlet and outlet grills clear
  2. Get your air source heat pump regularly serviced
  3. Monitor your system’s water pressure
  4. Avoid problems with the system water
  5. Ensure your controls are correctly set

Why is air source heat pump maintenance important? 

Regular visual checks of your heat pump combined with an annual service carried out by your heating engineer will help prolong the lifespan of your unit as well as helping the system to operate as efficiently as possible. If recommended servicing is not carried out, your heat pump's guarantee may be invalidated and if the unit is not regularly inspected, the heat pump's overall performance may be impaired. Here we explain the steps heat pump owners should take to look after their system. 

Tip 1 - Keep the air inlet and outlet grills clear

  • Regularly carry out visual checks of your heat pump
  • Remove any build up of snow, leaves or other debris
  • Do not block items around your heat pump

It is essential that your air source heat pump has an unobstructed flow of air running through it as this allows the heat pump to extract the heat needed to keep your home warm. If this air flow is restricted, it can limit the output of the heat pump and reduce the performance of your heating system.

Regularly checking your heat pump is an important thing to do. This is particularly necessary during the autumn and winter months when you need your heat pump most. Ensure that any obstructions, such as a build-up of leaves or snow which will affect the heat pump’s operation, are removed. Also, please do not stack items against your heat pump, for example bikes or fold-up garden furniture, as this could also restrict the airflow and affect the heat pump operation. View our YouTube video here to learn more about the importance of airflow around a heat pump

Tip 2 - Get a regular heat pump service  

Your air source heat pump should be serviced annually. This is usually a requirement for maintaining the appliance’s guarantee and regular servicing is also necessary if you are claiming the Government’s RHI payments for your renewable heating.

Your service should include:

  • checking the general condition of the heat pump
  • inspecting the flexible hoses and pipe insulation
  • checking the controller settings
  • cleaning the evaporator fins
  • removing any obstructions to the air flow

During the service, the heating system will also be checked including the system pressure and heating control settings to maintain reliable and effective operation.

Your heat pump can either be serviced by the company who installed it, a suitably qualified independent service engineer or you can contact our ServicePlan Team who can arrange for one of Grant UK’s own in-house engineers to service your appliance. To receive an air source heat pump service from a Grant approved heat engineer, get in touch with our team.

To find out more about the importance of heat pump servicing, please watch another of our YouTube videos.

Tip 3 - Monitor your system’s water pressure

All of Grant’s Aerona³ air source heat pumps must be used as part of a sealed heating system so it is important to regularly check the system pressure on the pressure gauge. This gauge will be found somewhere on the system, often on the manifold to which the expansion vessel is connected (your installer should have told you where this is). It is recommended to check the pressure when the system is cold and it should be around 0.7bar for a bungalow or around 1.2 bar for a two-storey house.


You can top up the system pressure if it has dropped below the desired level (either 0.7bar or 1.2bar depending on your property). This can be done using the filling link which will be located somewhere on the system and, again, is often connected to the manifold to which the expansion vessel is connected (the video tutorial here talks through this process).

If you find that you are having to regularly top up your system pressure, this may indicate a leak which will need to be investigated and dealt with so please contact your installer or service engineer for assistance.

Tip 4 - Avoid problems with the system water

It is important with all heating systems to make sure the system water is appropriately treated to prevent corrosion within the pipework and the radiators fitted to the system. If corrosion is able to build up within the system water, this can lead to a variety of issues including blockages in the heat pump, pipes, valves and radiators as well as radiator leaks which can all cause a reduction in the heat output of your system.

So, what can be done to prevent this from happening?

Fitting a magnetic filter in the system pipework, such as the Grant MagOne, can greatly reduce the amount of debris within your system and this can help reduce the likelihood of blockages causing future problems. Power flushing your system can also help to maintain the quality of your system water.

As heat pump systems operate at lower water temperatures that those with boilers, the use of a biocide is also recommended to prevent biological growth within the system pipework that may cause restrictions or blockages. Usually, your installer will have put a suitable additive(s) in the system to not only protect against corrosion and biological growth, but also to give anti-freeze protection to the heat pump during cold weather.

Tip 5 - Ensure your controls are correctly set

Your heat pump and heating system will be able to perform at their best if the controls are used correctly. Heat pump systems are not usually designed to heat your home and heat your hot water at the same time so the controls fitted by your installer will usually involve a simple two-channel programmer.

This programmer will then control when your heat pump is working to provide space heating and when it is working to heat your hot water. It is therefore important to check that this programmer is set correctly to control your system in accordance with your needs and demand.

Some control systems allow your heat pump to switch automatically from heating to hot water provision as and when required, so please speak to your installer to discuss these so-called ‘hot water priority’ controls further.

Achieve perfect room temperatures

You can also achieve your perfect room temperatures by using room thermostats as well as using TRVs (thermostatic radiator valves) which should be fitted to all or most of your radiators. Thermostatic radiator valves allow the temperature within an individual room to be set to a preferred level and, with minor adjustments, allow you to set your optimum room temperatures throughout your home. It is important to remember, however, that TRVs should not be used as an on/off switch for each radiator – once you have achieved your desired room temperatures, leave the TRVs alone.

Please be aware that, although your radiators may feel cool to the touch, this is not something to worry about. Your Grant Aerona³ heat pump is designed to work at lower operating temperatures than traditional gas or oil-fired boilers. Your radiators will feel cooler but this will not be a problem for heating your house as they should have been correctly sized to provide the required heat output at the lower temperature.

Finally, please do not tempted to tamper with the heat pump controller settings, such as the water flow temperatures, to try and raise the temperature of your radiators. The controller should be left as set by the installer to ensure that the system operates correctly.

To echo what we mention in the ‘Top Tips’ blog for oil boilers, use the room thermostat, TRVs and other user control systems to manage your room temperatures. This will help maintain the desired comfort levels of heating within your home while also helping your heat pump to operate as efficiently as possible.

Our final thoughts

As outlined in this blog, the top five steps homeowners can take to look after their air source heat pump include checking the airflow around the unit, arrange annual servicing, monitor the system pressure, protect the system water, and correctly set your controls.

To help you understand your heat pump system, a number of resources are available for homeowners to access. These include:

Receive air source heat pump guidance & support from Grant UK

If you are looking for a new heating system, discover more about the Aerona³ R32 heat pump range here and if you are already a heat pump owner, you can visit our dedicated Customer Support Centre. To find a local heat pump installer to fit your new Grant heat pump or to find a service engineer to service your heat pump, please use our online installer search to find local heat pump engineers.

Helen Rishworth
Content & Communications Manager at Grant UK
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