How Does an Air Source Heat Pump Work?

What is an Air Source Heat Pump?

The popularity of air source heat pumps in homes and commercial properties across Essex is no accident. These mechanisms are changing the way people heat their homes, all while reducing fossil fuel usage and helping the planet. 

Instead of burning oils or gases, air source heat pumps extract heat from the air outside, before transferring it into your home. From here it will heat your radiators and provide you with hot water, 350% more efficiently than the most modern boiler systems.

How Do Air Source Heat Pumps Work?

While the concept of the air source heat pump may be simple, the technology behind it is a little more complex. Let’s go through it step by step.

1. Absorbing Heat

The most notable aspect of air source heat pumps is the large fan on the front of the unit. This fan is responsible for drawing in the outside air. Even in the coldest temperatures, the air contains thermal energy (heat). 

The air then passes over heat exchanger coils which contain refrigerant liquid. This liquid can absorb heat at temperatures of around -15°C, which is why your heat pump will remain effective in the middle of winter. 

2. Heat Extraction 

The incoming air is a lot warmer than the temperature of the refrigerant, which begins to absorb its heat. It then starts to change from a liquid to a low-pressure gas, before entering the next stage of the process: compression.

3. Compression

The evaporated refrigerant is drawn into the compressor, which significantly warms its temperature. It does so by squeezing the gas molecules together, pressurising them and increasing the gas’ internal energy.

The refrigerant has now transformed from a low-pressure gas into a high-pressure gas.

4. Heat Transfer

The now-heated gas passes through a condenser. Its heat will then be transferred into the water for the central heating system which runs the other side of the condenser. Once the heat has been transferred, the refrigerant gas will pass through an expansion valve.

This expansion valve will suddenly release the pressure, quickly cooling the refrigerant. This will condense it back into a liquid, before the process restarts again.

As previously mentioned, the heat pump doesn’t use fossil fuels to instigate this process. Instead, the heat pump runs on electricity; but how much does it use?

[Want to know how air source heat pumps are installed? Check out our heat pump installation guide.]

How Much Electricity Does a Heat Pump Use?

Electricity consumption from heat pumps varies, but a standard 8kW heat pump will use between 180-300kWh per month. Electricity consumption will rise during the winter months, as the heat pump has to work harder to extract warm air. 

Despite the heat pump relying on electricity to run, it is still the most efficient home heating source there is. In fact, heat pumps are between three and four times more efficient than gas boilers, giving you plenty more heat for your money. Heat pumps can save you upwards of £350 a year on your energy bills.

Plus, if you invest in other forms of renewable energy in your home, such as solar panels and solar battery storage, you can save even more. 

Heat Pumps: Points to Consider

Before you go ahead with an air source heat pump installation, there are a few points you should consider. 

Adequate Insulation 

Heat pumps work best in well-insulated homes. While they can still operate if your home lacks high-quality insulation, you’ll run the risk of losing a lot of the heat that the pump produces. To counteract the heat loss, your pump will have to work harder, using up more electricity for a similar/worse result.

Correctly-Sized Radiators

Heat pumps operate at lower water temperatures than gas boilers. This means that you are likely to need larger radiators with greater surface areas to effectively heat the room. Unfortunately, this will add extra money onto the installation costs.

Government Grants

If you’re thinking about having an air source heat pump installation in Essex, you can capitalise on the UK Government’s Boiler Upgrade Scheme (BUS). This will shave up to £7,500 of your final bill, providing you choose a qualifying installation company. The discount will be automatically applied to your invoice, and you won’t have to fill out extra forms to access it. 

Bear in mind that the scheme is only set to run until March 31st 2028.

Shape, Size, and Noise Production

Heat pumps are not small and will require your home to have adequate outdoor space for installation. You will also need to make space indoors to store the water cylinder, which takes up a fair bit of space. Heat pumps aren’t silent either, which is another factor to consider when thinking about placement.