An air source heat pump is a low-carbon way of heating your home. They absorb latent heat from the outside air and use it to increase the temperature inside your home.  Air source heat pumps look similar to air-conditioning units. Their size depends on how much heat they'll need to generate for your home - the more heat, the bigger the heat pump. There are two main types of air source heat pumps: air-to-water and air-to-air. They work in different ways and are compatible with different types of heating systems.

Air source heat pumps are usually positioned outdoors at the side or back of a property. They need plenty of space around them for air to circulate. Inside, you'll usually have a unit containing pumps and hot water.  They are less disruptive to install than ground source heat pumps, as they do not require any digging in your garden. You won't normally need planning permission for an air source heat pump, but if you live in a listed building or conservation area, then you'll usually need the consent of your local authority. Also check that your installation will meet the building regulations in your area. Speak to your home insurance provider too to check if your policy will cover the changes to your heating system.

You'll need a place outside your home where a unit can be fitted to a wall or placed on the ground. It must have some space around it to allow a good flow of air.

The external unit for a heat pump is identical for both mono-bloc and split heat pumps. Noise is created by large fans moving air across the heat exchanger.Unless the heat pump is working very hard (ie in cold weather or producing high temperature water), you can expect the noise to be a similar volume to a fridge, if you were standing within a couple of metres. You could easily hold a normal conversation next to it, without raising your voice. As it gets colder outside, this noise will increase while it’s operating, but should still allow you to hold a conversation easily, only raising your voice a little.The inside unit for a split system only contains valves and pumps and makes very little noise at all.