Rinnai: how do commercial heat pumps work?

As we are all aware government rhetoric and legislation is leading to an increased interest in commercial heat pump technology for domestic hot water production and heating. This growing interest in commercial ground source and air source heat pumps is leading to many questions from gas installers, consultants, large commercial users, and the public. The questions are somewhat endless stemming from air source heat pump efficiency, ground source heat pump installation and much more!