The degree to which a heat pump can fulfill your needs at your home or business depends on its rating, whether it has a ducted or ductless air source (or ground source), the climate in your area, and the size of your home. A heat pump is rated according to its Seasonal Energy Efficiency Rating (SEER). Modern heat pumps have better coil designs and compressors, improved motors, and highly efficient fans, meaning excellent SEER ratings, high efficiency, and the ability to heat your home even when temperatures are below freezing.