The new MPi Series Rheem Heat Pump utilises the latest environmental heating technology to efficiently heat water. Free, renewable heat energy is absorbed and processed through a refrigeration system, resulting in hot water using a third of the energy of an electric water heater. These are similar saving to a solar water heater, but without needing panels mounted on your roof. Rheem Heat Pump models have a standard inclusion of a back-up element. Designed to activate only during very cold conditions, this feature ensures you have hot water, at the time you need a hot shower most.