While heat pumps have only entered the mainstream conversation in the past decade, the technology itself is anything but new. Air-source heat pumps extract heat from the air outside, even in freezing weather, and use electricity to compress the refrigerant into a hot, high-pressure vapour. While gas boilers generate heat by burning fuel, heat pumps move heat rathe than create it ( Ryan Jenkinson for Octopus Energy )The key difference between heat pumps and gas boilers is how they produce heat. Once installed, systems such as Octopus Energy’s Cosy heat pump provide steady, all-day heat – a key reason heat pumps are so popular in colder countries. Heat pumps typically last around 20 years, around five years longer than a gas boiler ( Octopus Energy )Running costs are where heat pumps increasingly shine.