Abstract: A heat pump comprising an evaporator, a compressor and a heat exchanger is provided. The evaporator transfers heat from taken in air to a first fluid and expels the taken in air at a temperature cooler than ambient temperature. The compressor compresses and pumps the first fluid. The heat exchanger comprises a first passage for the heated compressed first fluid driven by the compressor and a second passage for a second fluid driven by thermal convection. A heat pump comprising a second heat exchanger that receives heated compressed first fluid from the compressor which heats compressed first fluid from the heat exchanger is also provided. Additionally, methods and systems for heating a fluid are also provided.