Variable speed ECM technology has come of age and with it, savings of up to 85% in electrical costs as compared to conventional Circulators. The VR1816 ECM High-Efficiency Circulator (wet rotor) features infinitely variable fixed speed and 6 pressure presets to fit your job. It’s simple to install and intuitive to set up. Get into high-efficiency ECM savings with the turn of a dial – it’s efficiency uncomplicated. Fixed Speed Mode Fine tune the VR1816 ECM High-Efficiency Circulator flow rate to precisely match design load conditions. It is infinitely variable between min/max settings. Ideal for zoning with Circulators. Constant Pressure Mode The VR1816 ECM High-Efficiency Circulator maintains a constant pressure differential in the system as the heating load increases or decreases. The best option for zoning with zone valves. Proportional Pressure Mode Maintains a variable pressure differential in the system as heating load increases or decreases. Flow will change in relationship to the change in pressure differential. The best option for panel radiators with TRV’s.