What Maintenance Do Air Source Heat Pumps Need?

Homeowners considering low-carbon heating are often concerned about how much maintenance a heat pump will need. Heat pumps draw in air from outside and extract heat using a refrigerant fluid. The refrigerant is compressed, generating heat, and this heat is transferred to water, which circulates in the home. When you’re looking for efficient, sustainable home heating systems, heat pumps are a great option.

As with every major installation in your home, maintenance is a valid concern. Is heat pump maintenance going to take over your life, or will it just run perfectly forever?

Of course, the answer is somewhere in the middle. Heat pumps generally do not need more maintenance than a gas boiler. We recommend an annual service for most brands, and to schedule this for autumn to make sure the heat pump can cope with a sudden uptick in heat demand when winter weather blows in.

Why Regular Heat Pump Maintenance Matters

Regular maintenance is important for all mechanical systems in the home. Heat pumps are no different. They have a robust design, with minimal moving parts, but they still require servicing to keep them in good condition.

Air source heat pumps (ASHPs) extract environmental heat from the air using refrigerant fluid in an evaporator coil. The fluid vaporises at around 5°C and the pump pushes the vapour into a compressor. Compression creates heat, increasing the temperature to between 30°C and 50°C. The high pressure, high temperature vapour then enters the heat transfer unit or condenser coil, which brings it in close contact with cooler water inside the house. The water absorbs the heat, causing the refrigerant vapour to condense into low-temperature fluid. The pump drives this through an expander valve, depressurising it and returning it outside to the evaporator coil. The heated water is stored in a tank or distributed to the radiators to heat the interior.

All parts of the system should be checked and serviced during scheduled maintenance. This will help the ASHP work efficiently, keeping your electricity bills low. Regular maintenance also extends the lifespan of all components, helping you avoid costly repairs. It’s worth noting that without an annual service by an MCS-accredited engineer, your heat pump warranty may be void.

A well-maintained ASHP system can last between 15 and 20 years, so keep up with maintenance tasks to save money and help it work effectively.

Basic Heat Pump Maintenance Tasks

While your annual heat pump service should be carried out by a qualified MCS engineer, there are maintenance tasks you can carry out to support the proper working of your heat pump. These are small jobs that don’t need to take too much time.

Keep the Outdoor Unit Clean

These heat pump maintenance tasks should happen every three to six months, or any time you suspect your pump is not working effectively.

Keep at least 30cm clearance for airflow. ASHPs only work if they can draw in adequate air. Remove any potted plants or garden furniture out of the way to keep your pump working efficiently.

Remove leaves, dirt and debris from around the unit. Dirt and debris, such as dead leaves, can block the inflow, causing the heat pump to use more energy to run. Ventilation areas should also be clear to help the heat pump manage its internal temperature.

Check for ice buildup. It’s normal for heat pumps to be out in the elements, and frost or snow on top of the unit is not an issue. However, if there is ice all over the unit and on the coil inside, this may be a sign of deeper problems.

The condensation that normally forms on the coil is freezing, but heat pumps have a built-in defrost cycle to prevent any severe ice damage. If the ice is building up, the defrost system isn’t working as it should, due to broken sensors, stuck reversing valves or low refrigerant levels. If there’s no debris blocking the vents, contact an engineer as soon as possible.

Clean Filters

At least every three months, clean your heat pump filter. You will need to do this more frequently in times of high use, such as in winter, to prevent a build-up of dust and dirt from reducing the airflow. Regular filter cleaning improves your pump’s performance and keeps it working efficiently.

Start by turning off the power to your ASHP. After a minute or so, the pump will stop working, and it will be safe to remove the filter. Take the cover off the front of the heat pump and wipe it clean with a damp cloth.

Remove the filter and gently clean with a small brush or a hoover with a brush attachment. For some makes of heat pump, you can rinse the filter with warm water to remove all the dust and debris. Let it air dry fully before refitting it in the heat pump.

Check for Obstructions and Leaks

Regularly inspect the visible pipework for leaks and cracks. The ducts carry air and expel heat, and leaks lead to poor air circulation, reducing system efficiency.

Watch for unusual noises or vibrations, which could be a sign that key moving parts are coming loose or that bearings are worn. If you notice any leaks, knocking sounds or vibrations, contact a professional as soon as possible.

Professional Heat Pump Servicing 

These are the areas that need to be covered by a qualified and MCS-accredited engineer to keep your warranty.

Annual Service Checks

Once a year, book an engineer to carry out essential heat pump maintenance and inspections. These involve:

• tightening connections
• inspecting mountings and bearings in the fan
• replacing worn seals and fan belts
• cleaning air exchangers
• checking water exchangers for clogs
• cleaning water filters
• testing valves
• updating software if needed
• checking thermal insulation
• checking electrical wiring for signs of wear
• checking ducts for cracks and leaks
• checking refrigerant levels and topping up if needed
• lubricate moving parts

Heat pump maintenance specialists will avoid repeated visits by coming prepared to carry out standard maintenance during your service. You’ll receive a service report for your records.

Cost of Servicing

A typical heat pump service in the UK costs between £100 and £300. This includes the call out charge for the heat pump technician and minor repairs or replacements. If your heat pump needs a new compressor, you could pay up to £2000, but this is a very rare occurrence if the heat pump is properly looked after.

Some heat pump installers offer a service plan or maintenance contract for around £20 a month, which covers your annual servicing, making the cost more manageable.

Signs You Need a Professional Inspection

• Poor heating/cooling performance
• Strange noises, vibrations or odours
• Sudden increases in energy bills
• Frost or ice forming on the coils of the outdoor unit and not melting away

How to Extend the Life of Your Heat Pump

To get the longest possible use out of your air source heat pump, maintenance is vital. Make sure you clean filters every four to twelve weeks, keep air inlets and vents clear and unobstructed and keep checking on drains and ducting.

As well as annual servicing, the way you use the heating systems can prevent malfunctions. Keep thermostat settings stable to avoid overworking the system.

Choosing the Right Heat Pump Installer

If you’re facing more regular heat pump maintenance issues than expected and it’s costing a lot to keep it working, your pump may have been installed incorrectly. Choose an MCS-certified heat pump technician to ensure repairs are right the first time. If you don’t have a heat pump yet, or you think your system needs a full overhaul, choose the right heat pump installer to get a reliable service and benefit from government funding.

Rollings Renewables are experienced and approved air source heat pump installers in the West Midlands, trusted by hundreds of clients every year to install renewable energy solutions. With a great track record of five-star reviews and over twenty years’ experience providing electrical installations in commercial and domestic properties, Rollings Renewables offer simple solutions with fast results.