How does the no-flow shutdown (Option X) work?
The no-flow shutdown replaces the standard thermal bleed circuit on a pressure booster system. This option includes for a aquastat (thermostat), pilot light, and a pressure switch. The aquastat, normally used to actuate a solenoid valve on the thermal bleed, is used to actuate the shutdown of the pumps. The logic behind this is that thermal build-up in the seal flush line of the pump indicates that the pump is operating at no-flow. When the system temperature rises to a predetermined level (factory set at 80F), the pump is stopped. The system is turned back on by the call pressure switch, set to 5 psi below the design system pressure. A loss of 5 psi pressure on the system side will bring the lead pump back on. If this switch is not set below the system pressure, the system will run continuously building up temperature and destroying the pump seals. No flow shutdowns require the installation of a drawdown tank (bladder-type). Tanks ship charged to 12 psi, not the design pressure, due t
