Monday, June 20, 2011

Always Check the Pump Curve

Variable speed circulator pumps usually have three settings on which they can operate. This means they will have three different pump curves and can be used for a larger range of applications. Variable speed pumps are advertised, rightfully so, as an inventory reducer – meaning that contractors can carry them on their truck to use in a variety of jobs.

This is true, but we would advise a certain amount of caution. The three curves on a variable speed pump are almost always very similar: one central curve with the others slightly above and slightly below it. If an application calls for a flat-curved pump (high flow, low head), then a steep-curved variable speed circulator (low flow, high head) will not work – regardless of the setting. stocks variable speed pumps from Taco, Grundfos, Bell & Gossett, and Wilo.