Page 279 - HVAC Pump Handbook

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Basics of Pump Application for HVAC Systems

276 The HVAC World

Figure 10.2 Pump operation with system head area.

and then pick the pump to the left of the best efficiency point to ensure
that the pump will operate without damage at the higher flows and
lower heads. The other practice has been to install a balancing valve
on the pump discharge, either manual or automatic, and add enough
friction to prevent some of the operation at higher flows. One of the
advantages of variable-speed pumps is that this “carryout” condition is
eliminated by their controls without all the inefficiencies of pump
head conservation factors and balancing valves.

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