Air-to-water heat pumps
Unlike a typical air-to-air heat pump that blows warm air, an air-to-water heat pump heats water — perfect for radiators and radiant floors.
How an air-to-water heat pump works
An air-to-water heat pump extracts heat from outdoor air (like any air-source unit) but delivers it to water instead of air. That hot water then runs through radiators, underfloor heating, or a buffer/hot-water tank. It can also provide cooling via fan coils, and many models supply domestic hot water — making it a popular boiler replacement, especially in Europe.
Cost and best uses
Installed cost typically runs $10,000–$25,000+ depending on whether you reuse existing radiators/piping. It is ideal if you currently heat with a boiler and radiators or radiant floors and want to electrify without switching to forced-air ducts. Lower-temperature, larger-surface emitters (radiant floors, oversized radiators) help it run most efficiently.
Pros and cons
Pros: reuses hydronic heating (no ducts), very even comfort, can do hot water and cooling, no combustion. Cons: higher cost than air-to-air, works best at lower water temperatures (small old radiators may underperform), and fewer installers are experienced with it in the US.
Frequently asked questions
What is an air-to-water heat pump?
An air-source heat pump that heats water (for radiators, radiant floors or a hot-water tank) rather than blowing warm air. It is a common boiler replacement.
Can an air-to-water heat pump replace a boiler?
Yes — it can feed your existing radiators or radiant floors, though larger or lower-temperature emitters help it run efficiently.
Does it provide hot water and cooling?
Many models supply domestic hot water, and with fan coils they can also cool — a true all-in-one in suitable homes.
Related
Sources & further reading
Educational guide, reviewed against US DOE & ENERGY STAR guidance and updated June 2026. Estimates only — not a substitute for a professional assessment or Manual J load calculation.