Air to air heat pumps: cooling and heating in one unit

How it differs from a normal A/C unit

Technically the hardware is very similar: an outdoor unit linked by refrigerant pipes to one or more indoor units. The difference is that an air to air heat pump is designed and rated to heat efficiently all winter, not just cool on hot days.

What people pay

• One wall unit for an open plan ground floor: from about €1,900 fitted
• A multi split with indoor units in the main rooms: often €7,000 to €11,000 before the grant
• Ducted systems with hidden vents: at the top of the range, and a messier install of two to three days

Wall units or ducted?

Wall units are cheaper to buy and run, and quick to fit when the rooms share an outside wall. Ducted systems hide everything in the ceiling and can reach bathrooms and hallways, but cost more to install and a little more to run.

What about the bathroom?

Wall units aren't usually fitted in bathrooms. Most owners add an electric towel rail, or leave the bathroom door open to the heated landing. A ducted system can include the bathroom.

And hot water?

• Keep your existing immersion and run it on a night or smart tariff
• Add a heat pump hot water cylinder, which has its own small heat pump and uses far less electricity than an immersion
• Keep the gas boiler for hot water only, if you have one

Good for

• Apartments with electric storage heaters
• Extensions and garden rooms
• Homes built from about 2000 on, with good insulation
• Homes that want cooling and efficient heating in the main rooms

Less good for

• Heating every room in a large house: air to water usually does that better
• Homes that rely on the boiler for hot water: you'll need an alternative