Gas-fired heat pumps are neither economical nor efficient for single-apartment or single-house systems. Internal combustion engines with shaft power output of 1

Gas-fired heat pumps are neither economical nor efficient for single-apartment or single-house systems. Internal combustion engines with shaft power output of 1-2 kW are inefficient, loud and maintenance intensive. They can start to make sense from around 50 kW heating/cooling capacity and upwards, so the smallest units are suitable for 8-15 apartments depending on size.