How does a heat pump work?
Simply put, a heat pump provides heating in winter months by extracting heat from outside a building and moving it inside.
While there are various types of heat pumps, we’ll focus on air source heat pumps. These are designed to replace traditional oil and gas boilers and are the type of heat pump that will be available to all through the Switch Together heat pump group-buying scheme.
What is an air source heat pump?
There are two main types of air source heat pump, air-to-air and air-to-water. Air-to-air systems tend to be more common in countries that have air conditioning units installed in homes. In the UK, an air-to-water heat pump is a highly efficient system that extracts heat from the outside air and transfers it to water. This heated water is then circulated through radiators or underfloor heating to warm your home. Additionally, it can supply hot water for your taps, showers, and baths by heating water stored in a hot water cylinder.
How does an air source heat pump work?
Let’s break down how an air source heat pump keeps your home warm and cosy:
- Capturing heat from the air
Even when it’s chilly outside, there’s still heat in the air. The heat pump starts by drawing in this heat, using a fluid that can absorb it efficiently. - Heating up
Once the fluid has absorbed the heat, it’s pumped through a heat exchanger inside the pump. Here, the magic happens—the fluid's temperature increases significantly. - Warming your home
This heated fluid then transfers its warmth to water. The new hot water circulates through your heating system, providing warmth throughout your home and hot water for your taps and showers.
Think of it like a fridge but in reverse. Instead of cooling, its job is to heat. It is able to do this more efficiently than a traditional heating system because it uses a refrigerant. Refrigerants are substances that can easily change from a liquid to a gas and back again, allowing them to absorb and release heat efficiently. The technology is well established, having been around for over 150 years and well adopted in Scandinavian countries.
How efficient are heat pumps?
Overall, heat pumps are very efficient at heating your home. Air source heat pumps can exceed 300% efficiency (three to four times more efficient than your gas or other traditional heating system) as they transfer heat rather than generate it. Of course, the efficiency depends on how hard they have to work to maintain a comfortable room temperature in your home. The primary factor is the difference between the desired temperature in your home and the temperature outside.
Have a look below at how a heat pump compares to more traditional heat sources.
To put this into context, the average UK home uses just over 13,000 kWh of oil or gas per year to produce 12,000 kWh of heating. A heat pump would deliver the same amount of heat from only 4,000 kWh of electricity.
How can a heat pump generate heat when it’s cold outside?
Even in cold weather, enough heat energy is in the air. An air source heat pump can use this residual heat in temperatures as cold as -20C. It does this through a process of heat absorption and compression, allowing you to heat your home even when cold outside. The Scandinavian countries are well known for their sub-zero temperatures, but over 40% of homes in Norway have a heat pump installed, highlighting the system's performance in colder climates.
Interesting fact: Warmth is present in all air with a higher temperature than absolute zero, which is -273.15C. This is because atoms and molecules continue to move until that extreme point.