An air water heat pump is like an air source heat pump but it transmits the recovered heat to a backboiler, from where heat can be utilized for domestic warm water and rooms. Room heating requires a water-based radiator or floor heating system. An air water heat pump is more affordable and easier to install to an existing building and suits smaller buildings compared to geothermal heating.
An air water heat pump can produce nearly all thermal energy needed for a detached house (for rooms and domestic warm water) in southern and central Finland, and electrical resistance is needed only during the coldest weather to produce the extra warmth. An air water heat pump can be made into a hybrid system with a solar collector and a fireplace connected into one backboiler. Applicable to both new and repair construction. An air water heat pump also works with an oil-fired boiler in good condition, reducing oil consumption to a fraction.
An air water heat pump is less expensive than geothermal heating measured by a single well, and it gives return on investment in 7–10 years. The carbon footprint of the heat produced is approximately 40 g CO2/kWh.