None of these methods comes close to the energy savings achieved by a variable-speed drive and may cost even more money due to maintenance. Add in the difficulty of sourcing spare parts as these solutions become obsolete and cease to be supported by the manufacturers and the costs can stack up. And when they fail, you could be left with a major interruption to production that could cost thousands more.
By contrast, using a variable-speed drive to replace a damper in a ventilation system running, on average, at 80 percent speed can save a fortune.
Simply turning down the speed of an 11 kW motor to 80 percent saves £2,599 per year. Perhaps it’s time to update your flow control?