Air-to-Water vs Air-to-Air Heat Pumps Ireland — Which Is Right for You?

When most Irish homeowners talk about installing a heat pump, they mean an air-to-water system. But air-to-air heat pumps are also grant-supported by SEAI and suit some home situations better.

How each system works

Air-to-water heat pump:

Extracts heat from outdoor air
Transfers it to water in a closed circuit
Heats your radiators and/or underfloor heating
Heats your domestic hot water cylinder
Replaces your oil or gas boiler completely

Air-to-air heat pump:

Extracts heat from outdoor air
Delivers warm air directly via indoor units (like a reverse air conditioner)
Can also cool in summer
Does not heat domestic hot water. You still need a separate hot water solution.
Common in new apartments and commercial settings

SEAI grants comparison

	Air-to-water	Air-to-air
Unit grant	€6,500 (manual, 2026-09-22)	€7,500 (manual, 2026-09-22)
Central heating upgrade	€2,000 (manual, 2026-09-22)	✗ Not available
Renewable heating bonus	€4,000 (manual, 2026-09-22)	✗ Not available
Maximum total	€12,500 (manual, 2026-09-22)	€7,500 (manual, 2026-09-22)

Source: SEAI, source date 22 September 2026 (manually researched)

The individual scheme gives air-to-air a higher unit grant (€7,500 (manual, 2026-09-22) vs €6,500 (manual, 2026-09-22)), but air-to-air can’t access the central heating or renewable bonus grants.

Which is right for your home?

Choose air-to-water if:

You currently have oil or gas central heating and want to replace it completely
You have or want radiators / underfloor heating
You want a single system for both space heating and hot water
Maximum SEAI grants are important to you (up to €12,500 (manual, 2026-09-22) total)

Consider air-to-air if:

You’re in a new-build apartment with no central heating
You want summer cooling as well as heating
Your home is very well insulated and you have a separate hot water solution
You’re adding supplemental heat to a property with electric storage heaters

Installation comparison

	Air-to-water	Air-to-air
Replaces boiler	✓ Yes	✗ No
Heats hot water	✓ Yes	✗ No
Summer cooling	Some models	✓ Yes
Typical install time	2–4 days	1–2 days
Installation complexity	Higher (pipework)	Lower (ductless)

For most Irish homeowners switching from oil or gas, air-to-water is the right choice. See our full heat pump cost guide for installed price ranges.

Frequently asked questions

What is the difference between air-to-water and air-to-air heat pumps?

Air-to-water heat pumps heat water for radiators, underfloor heating, and a hot water cylinder, providing a complete central heating replacement. Air-to-air heat pumps heat and cool air directly but don't heat domestic hot water.

Which heat pump type gets a higher SEAI grant?

The cost depends on the specification and work required. Compare written, itemised quotes for your property, and check any applicable grant separately.

Are air-to-air heat pumps suitable for older Irish homes?

Air-to-air systems can be a good option for supplemental heating or modern, well-insulated homes. However, they don't replace hot water heating and are less common in traditional Irish homes with oil or gas central heating.