There are two possible methods available for enabling a (relatively) low-pressure circulation of the pump delivery flow if it is needed elsewhere (excluding turning off the drive motor):
- The three-way valve has a centre position for pump circulation (Figure P 38 a). This cost-effective solution is only practical for smaller flows and, over larger distances, causes noticeable pressure losses between the pump and the valve.
- An integrated pump idle circulation valve which can be connected directly to the pump, ensures a practically pressure-free circulation (Figure 38 b).
Figure P 38: Pump direction switching