Heat pump (PAC, Pompe a chaleur): French types and terminology explained

How does a heat pump (pompe à chaleur) work?

A heat pump doesn't burn fuel. It pulls warmth out of the outside air (or the ground) and moves it indoors, much like a fridge running in reverse. Even on a cold day there's enough warmth in the air to extract.

Installers measure efficiency with the COP (coefficient de performance). A COP of 3 means 3 kWh of heat for every 1 kWh of electricity. The figure drops as the weather gets colder. That's why the Cote d'Azur suits heat pumps: even in January, the coast rarely gets cold enough to cut performance much.

What does PAC réversible mean?

Most heat pumps fitted in French homes are reversible. They heat in winter and cool in summer, working like an air conditioner when the cycle runs backwards. You'll see "PAC réversible" on quotes and spec sheets. To be sure a unit is reversible, check the manufacturer's spec sheet, not just the quote.

One machine for both seasons is why these units are so common on the Cote d'Azur. The subsidies are a different story. Since January 2025, MaPrimeRénov' hasn't covered a standalone PAC air-air. A PAC air-eau still qualifies, but only in your principal residence. CEE credits can still apply to an air-air unit if it meets an efficiency threshold, so ask the installer to confirm it does.

What is the difference between a PAC air-air and a PAC air-eau?

The two terms describe how the heat reaches you indoors:

• PAC air-air: warms or cools the air directly, through indoor units (splits) on walls or ceilings. It's the most common type in the south of France. It doesn't heat water for taps or radiators.
• PAC air-eau: heats water that runs through radiators, underfloor heating or a hot water cylinder. It usually replaces a boiler and suits homes that already have radiators. Old, small radiators may need replacing, so ask the installer to check yours.

A ground-source heat pump (PAC géothermique) is the third type. It draws heat from pipes buried in the garden or from a borehole. It costs much more to install and needs land, so it's rare in the region. On the coast it's only slightly more efficient than an air-source unit.

What a PAC devis should show before you sign

A quote for a PAC names the brand and model of the outdoor unit (groupe extérieur) and each indoor unit (groupe intérieur, or split). It gives the heating capacity in kW. Ask how that size was worked out: it should come from a heat loss calculation, not from floor area alone. The quote should also list the unit's efficiency ratings for heating and cooling. For an air-air unit, those ratings decide whether you get CEE credits and the reduced TVA rate, so ask the installer to confirm the unit qualifies.

More on heat pump grants and quotes

• MaPrimeRénov': the government grant for air-to-water and ground-source heat pumps in a principal residence
• RGE certification: for heat pump installers, the QualiPAC label
• Devis: the written quote you'll receive before any installation
• Heat pumps on the Cote d'Azur: costs, subsidies and how to choose an installer