Armstrong’s IVS system allows an HVAC system to operate more efficiently by varying the pump speed to respond to changes in system demand. Many constant speed installations use valves to control system flow. This leaves the pump operating at full speed, wasting energy, in periods of low demand. Varying the pump speed in concert with system demand avoids wasting energy. That leads to cost savings through reduced energy usage and reduced maintenance costs. It also extends the life of the installation.