While variable frequency drive technology (VFD) for controlling pump speed has been used for many years in industrial and commercial markets, it has exploded more recently in the residential water well market. This is due to VFDs that provide the benefit of constant pressure and are easy to install. Now there’s a new twist in constant pressure technology. The MonoDrive from Franklin Electric, of Bluffton, Ind., is a constant pressure controller using variable frequency drive technology with a single-phase motor. ? Circle 203 on Reader Service Card ?