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1Domestic water supplyGrundfos DWS familyDWS product selectionMatching consumption and pumpcapacitySelecting the right pump is a matter of matching waterconsumption with pump capacity. For bestperformance, avoid installing an undersized oroversized pump. Consumption may vary greatlydepending on housing standards and lifestyle. Forexample, lawn sprinkler systems in the summer canincrease consumption.Pump selectionPump selection is based on the water demand andrequired system head.The water demand depends on the number ofconsumers connected to the system.Head can either be expressed in feet or psi. Headrefers to static head, pressure head, and friction head.For assistance with pump selection, refer to theWebCAPS product selection program; a link to CAPSmay be found on the Grundfos website.PipingIn any water supply system, the sizing and choice ofmaterials of the pipework has an impact on the choiceof pumps and on the cost. Piping takes into accountthe system head as referred to in Pump Selection.Static head is the distance from the ground water levelto the uppermost tap. Pressure head is the systempressure the user wants to achieve.In most residential application this pressure isapproximately 60 psi. Friction head depends on thepipe size, type and length.When calculating friction loss remember to allow fordeterioration in the piping schematic, since all waterpipes will eventually become coated with rust, limedeposits, etc.Flow velocity in the piping must be kept low as noisecan occur due to turbulence in elbows and valves orfrom water hammer.Fitting a pressure relief valve in the discharge piping isrecommended to protect the piping from over-pressuredue to system malfunction.Pressure tanksA pressure tank should be installed in order tominimize the number of pump starts and stops in thewater supply system, and to reduce problems withwater hammer in the pipework.Tanks are included with the BMQE Constant PressureSystem and the MQ. The BMQE system has anexternal tank. The MQ has an internal tank.Jet pumps, however, may require the addition of a tankdepending upon the application.Pressure switchesPressure switches are used to control pump operation.These switches have a cut-in pressure and a cut-outpressure to turn the pump on and off.The BMQE Constant Pressure System includes apressure transducer for constant pressure. The MQhas a built-in pressure switch. Jet pumps have anattached pressure switch.ValvesCheck valvesA check valve is a mechanical device which normallyallows fluid to flow through in only one direction.The BMQE Constant Pressure System and the MQhave built-in check valves. For suction lift applicationswith the MQ, a check valve (provided) is required atthe inlet.Foot ValvesA foot valve is required when pulling a suction lift(shallow or deep well) with a Jet pump. This valve isinstalled at the end of the suction pipe to prevent backflow. The MQ will also benefit from the use of a footvalve with suction lift applications.Shut off valvesShut off valves in the piping system make it possible todrain only the part of the system that needs attentionor repair.Flow control valvesFlow control valves are used in applications where aset flow (gpm) is required; for example, a shower heador an irrigation system.Pressure reducing valvesPressure reducing valves are used in applicationswhere the incoming water pressure exceeds themaximum inlet pressure of the pump as is the casewith the MQ and city water pressure. The pressurereducing valve (PRV) is used inline after the city watertap and before the pump to ensure a set pressure.Pressure relief valvesThis valve is a spring controlled device that can beadjusted to meet the needs of the pumping system.Pressure relief valves are used in applications wherehigh pressure can result in damage to accessories; forexample, tanks with maximum pressure ratings.4