Air-to-water heat pump installation.

An air-to-water heat pump — also called a hydronic heat pump — moves heat from outdoor air into water, then circulates that water through your home via radiators, radiant floors, or baseboards. It’s a direct electric replacement for an oil or gas boiler. “Air-to-water” describes the heat-transfer (outdoor air → indoor water); “hydronic” describes the distribution (water flowing through pipes to your emitters). Same equipment, two common names.

A “regular” heat pump (air-to-air) pushes heated or cooled air directly into your home through ducts or wall-mounted heads. An air-to-water heat pump heats water instead — and that water carries the heat through your existing hydronic distribution. Different output medium, same heat-pump principle.

Usually yes, but it depends on the radiator size and your home’s heating load. Air-to-water heat pumps are most efficient producing lower-temperature water (110–140°F) than what an oil boiler typically supplies (180°F+). Older homes with undersized radiators may need a high-temperature heat pump model, oversized radiator replacements, or supplemental electric heat for the coldest days. Your Home Advisor will tell you which path fits during the assessment.

Some air-to-water systems can — by adding fan coil units that blow cool air across chilled water from the same heat pump. Confirm with your Home Advisor whether the brand and model we’re recommending supports cooling, and whether your home’s distribution can be adapted (radiant floors generally cannot cool; fan coils can).

Yes. Most air-to-water heat pumps can integrate with a domestic hot water tank — either built into the indoor cylinder or paired with an indirect tank. One heat pump, two jobs. If you’d rather keep your existing hot water system, you can run the air-to-water for space heating only and pair it with a standalone HPWH for hot water.

Usually yes. A buffer tank stores heated water between the heat pump and your distribution loops, smoothing demand spikes and preventing the heat pump from short-cycling. Sizes vary based on your home’s load and the heat pump’s capacity — your design will spec the right tank.

Air-to-water is fully electric — no fuel deliveries, no combustion exhaust, no chimney. It typically costs more upfront than a boiler replacement but is 3–4× more efficient on heating, so operating costs drop. For oil-boiler replacements especially, the long-term cost difference is significant; for gas-boiler replacements, the math depends on local gas vs. electric rates.

Typically 1–2 days on-site, plus removal time if we’re pulling an old boiler. Day one: outdoor heat pump set, refrigerant or hydronic lines run, buffer tank and circulators installed. Day two: connections to existing distribution, commissioning, supply-temperature calibration, walk-through. Boiler removal can add another half-day to a day depending on fuel type.