Carrier GC Series Installation Instructions Manual

9Typical Open Loop PipingOpen loop systems require a water solenoid valve to turn on thewater when the heat pump compressor is energized, and to turn offthe water when the compressor is off.A slow--closing motorized valve (MVBR3F or MVBR4F) isrecommended to help reduce water hammer. A flow regulatorlimits water flow to avoid using more water than the heat pumprequires, which wastes water and increases pumping costs. A hosekit provides vibration isolation, as well as convenient fittings toinstall P/T (pressure/temperature) plugs for checking watertemperature and pressure drop at start--up and duringtroubleshooting.Fig. 8 shows the typical piping arrangement for a single solenoidvalve. For single speed heat pumps and smaller two--stage heatpumps (3 tons and smaller), one valve is typical. For largertwo--stage heat pumps, there is an opportunity to save a significantamount of energy (and avoid wasting water) with the use of twosolenoid valves, one for first stage, and both for second stage (Fig.9).1” hose barbx 1” MPT*1” rubber hose*P/T Plug*Heat PumpElbow*MVBR4F solenoid valvePart of HK4MM hose kitConsult local regulations for discharge requirementsConsider variable speed pump in place of pressure tank and pressure switchLWTEWT1” MPT x 3/4” MPT******†††1” ball valvePiping to discharge***Heat Pump1” hose barbx 1” MPT*(optional)1” ball valvePressure Tank†SubmersiblePump††MVBR Solenoid Valve Flow RegulatorFig. 8 -- Single Solenoid ValveSolenoid ValveStage OneSolenoid ValveStage TwoFlow RegulatorStage OneFlow RegulatorStage TwoBall ValveFrom Heat PumpNOTE: Wiring kit #4129 is recommended for easy 24 volt connection staging solenoids with compressor.Fig. 9 -- Two Solenoid Valves