Heat Pump Pollution: Filtering The Facts

Heat pumps are a popular choice for those wanting to heat and cool their homes in a more sustainable way than traditional HVAC systems. They are also a good option for those wanting to improve the air quality of their homes. Heat pumps have a filtration system that reduces the amount of dust, pollen, and other particles in the air. However, the heat pump industry has been criticised for its use of harmful chemicals, such as PFAS, which have been found to have a high global warming potential and to be toxic to the environment.

Heat pumps can reduce indoor pollution

Heat pumps can help reduce indoor pollution. They use the air outside to exchange heat in and out of the home, and that air carries dust, pollen, and other particles. Heat pumps have a filtration system to make the air cleaner and reduce wear and tear on parts. All heat pumps will have some sort of filter. It could be a simple paper filter, a HEPA filter, or a fancier plasma or ionic filter.

The selection of a heat pump filter requires balancing the MERV rating, which indicates filtration ability, with the pressure drop, which indicates airflow restriction. The higher the MERV rating, the better the filtration, but the greater the pressure drop, the harder the system must work and potentially the shorter its lifespan. A MERV 8 filter blocks 90% of particles that are three to ten micrometres in size. If you are worried about wildfire smoke, welding fumes, and other very fine particles in your home’s air, you can get a filter above MERV 8.

Ductless heat pumps have removable and washable filters that are easy to clean. This helps reduce indoor pollutants. Experts recommend cleaning your heat pump filters every two weeks during peak seasons and replacing them once a year. This regular maintenance helps keep the air in your home clean. Air purifiers can be added to a heat pump system to further enhance indoor air quality. However, heat pumps require less filtration than traditional HVAC systems because they do not burn any combustion products to exchange heat.

It is important to keep your heat pump well-maintained. When the filters get clogged, the heat pump gets dustier, which is where damage can result. The filter also gets less effective at its job of keeping pollutants out of your home. This can cause health issues such as headaches, allergic reactions, and even dizziness. Long-term, they could trigger asthma, heart disease, and even cancer. Consistent filter changes can help stop this from happening so your unit runs exactly as it should for its entire lifespan.

Filters need regular cleaning or replacing

Heat pump filters should be checked at least once a month. If the filter is covered in a thick layer of dust and debris, it may be possible to gently clean it and extend its life. However, if the filter is black or dark grey, or if you cannot see through it, it should be replaced as soon as possible. Some sources recommend replacing the filter every three months, or even every one to two months if anyone in the household has allergies, asthma, or other breathing issues. If you have pets, you may need to replace the filter more frequently, as pet hair and dander will clog the filter more quickly.

When replacing a heat pump filter, first turn off the machine. Open the cover of the unit and slide out the filter. If you are allergic to dust or have asthma, it is recommended to wear a face mask, gloves, and goggles. Inspect the filter for dust or buildup, and if it is visibly dirty, remove it. Use a vacuum to suction any dust or debris left in the filter housing. Some sources recommend vacuuming the filter itself before putting it back. When putting the filter back, ensure it is dry and align it using the directional arrows on the filter and the filter housing. Close the housing door securely.

It is important to note that some heat pump filters are not reusable and must be replaced. Paper filters, for example, need to be thrown away and replaced with new ones. Additionally, some heat pumps have multiple filters, with smaller filters that need to be replaced every couple of years. It is important to refer to the manufacturer's instructions to determine the proper cleaning and replacement procedures for your specific heat pump model.

Filters can get clogged, causing issues

Filters can get clogged with dust, debris, and other contaminants from the circulating air. When this happens, the heat pump gets dustier, and the air cannot flow properly. This puts more strain on the heat pump, causing it to work harder and reducing its efficiency. A clogged filter can also lead to poor indoor air quality as pollutants may re-enter the home's air. These pollutants can cause headaches, allergic reactions, and even dizziness. Over time, they could trigger asthma, heart disease, and potentially cancer.

A clogged filter can also cause the heat pump to run hotter, putting more strain on the indoor unit fan motor, which can burn out prematurely. Additionally, the increased dust and grime can lead to friction on the moving parts inside the heat pump, further reducing its lifespan and increasing the possibility of a serious breakdown.

Clogged filters can also drive up energy use, resulting in higher monthly bills. They can also cause hot and cold spots in the home and impact the humidity levels, creating an environment conducive to mold growth and the thriving of dust mites and allergens.

To prevent these issues, it is important to regularly clean or replace the filters. Most filters need to be swapped out every 2-3 months, while others recommend cleaning the filters every two weeks during peak seasons and replacing them once a year. Regular maintenance ensures the heat pump functions optimally and maintains good indoor air quality.

Heat pumps may contain toxic chemicals

Heat pumps can improve air quality through their filtration systems, which remove dust, debris, mould spores, pollen, dust mites, and other allergens and pollutants from the air. However, if not properly maintained, heat pumps can also contribute to poor indoor air quality and health issues. It is important to regularly change or clean the air filter to prevent the build-up of pollutants, which can cause allergic reactions, headaches, dizziness, and, in the long term, trigger asthma, heart disease, and even cancer.

While heat pumps themselves do not typically contain toxic chemicals, the synthetic refrigerants used in some heat pumps, such as hydrofluoro-olefins (HFOs) and hydrofluorocarbons (HFCs), have been associated with environmental and health concerns. Perfluoroalkyl and polyfluoroalkyl substances (PFAS), a group of synthetic chemicals containing carbon and fluoride atoms, have been found in groundwater, fruits, vegetables, and spices, and have been linked to severe health issues, including damage to the liver and immune system, an increased risk of certain cancers, low birth weight, birth defects, and developmental delays.

HFCs, commonly used in heat pumps, are members of two dangerous chemical families but are considered much safer than their relatives. They were developed as replacements for chlorofluorocarbons (CFCs), which were found to destroy the ozone layer. HFCs were heavily vetted for safety before being introduced as refrigerants, and studies by the OECD in 2004 and 2005 found that common heat pump chemicals had "a low hazard profile" for human health. However, HFCs are potent global warming gases, and regulators are setting stricter limits on their use.

While the available toxicological evidence suggests that HFCs in heat pumps pose no significant risk to human health, there are concerns about the broader PFAS chemical family, which includes highly toxic pesticides. PFAS have been linked to environmental poisoning and are considered "forever chemicals" due to their durability. Regulations restricting the use of PFAS are being discussed, and natural refrigerants are promoted as a non-toxic, efficient, and cost-effective alternative.

Higher-rated filters improve air quality

Heat pumps use the air outside to exchange heat in and out of a home. This air carries dust, pollen, and other particles, which can cause health issues like asthma and allergies. Therefore, heat pumps have a filtration system to make the air cleaner and reduce wear and tear on parts.

The effectiveness of the filtration depends on the type of filter used. Filters are rated on the MERV scale, from 1 to 16, with higher MERV ratings indicating better filtration. A MERV 8 filter, for instance, blocks 90% of particles that are 3 to 10 micrometres in size, including mould spores, dust, and most aerosol particles. Higher-rated filters, such as MERV 16, can filter out smaller particles, which is beneficial for those with allergies, asthma, or living in high-pollution areas.

Heat pump filters need to be regularly cleaned or replaced to maintain good air quality. A neglected air filter can become clogged with dust, dirt, and debris, reducing the efficiency of the heat pump and potentially causing damage to its components. Consistent filter changes and maintenance can help prevent this, ensuring the heat pump functions optimally and provides improved air quality.

While higher-rated filters offer better filtration, they also restrict airflow more, so it is important to balance filtration ability with airflow restriction when choosing a filter. The ideal filter should provide effective filtration while minimising airflow restriction. Consulting a professional HVAC technician can help determine the optimal filter choice based on specific requirements and the capabilities of the heat pump system.

Frequently asked questions