Grundfos Hydro Multi-E Duplex Constant Pressure Booster - DOE PEI 0.38-0.45

Hydro Multi-E Duplex is a factory-built constant-pressure booster: two Grundfos CRE vertical multistage pumps piped in parallel on a common stainless steel base frame, with AISI 316 inlet and outlet manifolds, an isolating valve on each side of every pump, a check valve per pump, pressure gauges, two outlet-pressure sensors, dry-running protection and a breaker cabinet. It is pre-piped, pre-wired and pressure- and function-tested at the factory, and arrives ready to connect.

There is no separate control panel. Each pump carries a Grundfos MLE permanent-magnet motor with its own frequency converter and PI controller, and the pumps talk to each other. The system holds one outlet pressure by varying speed, cuts pumps in and out as demand changes, and alternates duty so run hours even out. Constant pressure is the factory setup; proportional pressure, setpoint influence, pipe filling and limit-exceeded monitoring are built in.

Built for sites where the water cannot stop. Any pump with an outlet-pressure sensor can take over as master, and two outlet sensors are standard, so the system keeps running if one pump or one sensor drops out. Optional Grundfos CIM modules put it on the building management system over BACnet MS/TP, BACnet IP, Modbus RTU, Modbus TCP, PROFINET or EtherNet/IP, or on Grundfos iSolutions Cloud. That combination, plus DOE PEI-rated pumps, is why we offer it for data centers, hospitals, hotels and office buildings.

This listing covers the CRE 10, CRE 15 and CRE 20 builds, the sizes that carry a DOE Pump Energy Index. Hydro Multi-E systems with CRE 3 and CRE 5 pumps sit outside the DOE PEI scope and are listed separately: Hydro Multi-E Duplex with CRE 3 and CRE 5.

Standard hydraulics expect a flooded or pressurized inlet. For suction lift, Grundfos moves the check valve to the inlet side as a factory option, specified at order. The system is rated for indoor installation only.

Hydro Multi-E ships as a factory-built duplex or triplex, chosen at purchase. Each added pump adds flow at the same pressure, and the system cascades pumps in and out on demand, so a light load runs one pump slowly and a peak runs all of them. The triplex version is listed separately: Hydro Multi-E Triplex.

More pumps hold more pressure at the flow the building actually draws. Each pump carries a share of the water, so each sits higher on its own curve. Grundfos draws the one-, two- and three-pump curves for every build on the same chart in the data booklet (printed pages 35 to 37), so the gain can be read straight down a flow column: at 240 GPM a CRE 15-3 system adds 114 ft (49 psi) on two pumps and 165 ft (71 psi) on three. The shut-off pressure at zero flow is the one figure that does not rise, because it is set by the pump build.

Figures read from the Grundfos CRE 15 curve chart, Data Booklet 99347082, printed page 36.

PEI is the U.S. Department of Energy yardstick for clean-water pump efficiency. It is the pump energy rating divided by the rating of a pump that only just meets the federal standard for its type. A value of 1.00 is the legal ceiling; pumps above it could no longer be manufactured after January 26, 2020. Lower is better: a PEI of 0.38 means the pump is rated at 38% of the energy the minimally compliant baseline would use at the DOE test points.

Two versions exist. PEI_CL (constant load) applies to a bare pump or a pump sold with a motor. PEI_VL (variable load) applies to a pump sold with a motor and a speed controller, which is how every CRE pump on this system is supplied, so these are PEI_VL figures.

PEI_VL of each individual CRE pump. Grundfos states that the packaged skid does not carry a PEI value of its own, only the pumps in it do, and that PEI is a generalized value that cannot be used to calculate efficiency in a specific application. Source: Grundfos Hydro Multi-E Data Booklet 99347082 (10.2025), printed pages 3 and 4.

Every build comes in two dry-running protection versions with different part numbers. Inlet pressure switch versions (part numbers beginning 99334, 99445 and 99449909) use a normally open switch on the inlet manifold that stops the pumps at 3 psi and resets above 5 psi. Inlet pressure sensor versions (part numbers beginning 99761) carry two inlet-pressure transducers, one to each master motor, with the trip level set in the operating panel or Grundfos GO. The sensor version also reads the actual inlet pressure, which proportional-pressure and limit-exceeded functions can use.

Max boost is the peak of the curve near zero flow, a ceiling rather than a working point; max flow is the end of the duplex curve. Both read from the Grundfos curve charts (Data Booklet pages 35 to 37). HP is the rated motor power (P2) per pump. Part numbers and model pairings from the Grundfos price list effective January 1, 2026, checked against the part-number tables in Data Booklet 99347082. Weights and connections from the Data Booklet, printed pages 43 to 46.

Voltage is fixed per part number. The MLE motor has no terminal-board changeover, so single-phase and three-phase units, and 200-240V and 440-480V units, are not interchangeable. Confirm the service before ordering.

From the Grundfos dimensional drawing: A is pump height, A1 breaker cabinet height, B length, C depth; overall height is the taller of A and A1. Dimensions may vary by plus or minus 0.5 in. Net weight is the system; gross weight includes packing. On the CRE 20-1 and CRE 20-2 rows (and CRE 20-3 at 440-480V) Grundfos prints dimension B as 30 in (909 mm); the two figures disagree, so confirm B on the certified drawing before laying out the room. Grundfos asks for one meter (3 ft) of clearance on all sides for inspection and removal. Source: Data Booklet 99347082, printed pages 43 to 44.

Sources: Data Booklet 99347082 (10.2025) pages 3 to 13 and 51 to 53; Installation and Operating Instructions 98419766 pages 26 to 29; Hydro Multi-E brochure (11.2025) and leaflet LHMESL02 (07.2024) for approvals.

Maximum feeder overcurrent protective device rating for the whole system, as printed by Grundfos. Supply tolerance plus or minus 10%. Motors of 5 to 7.5 HP need an especially reliable earth connection because leakage current exceeds 3.5 mA. Source: Installation and Operating Instructions 98419766, page 28.

A pump curve plots what the system adds to whatever pressure arrives at the inlet — never the discharge pressure and never the setpoint. Each cell reads feet of head added (psi added). The one-pump row is what the system delivers at low demand, before the next pump cuts in.

CRE 10 builds — flow in US GPM across the top

CRE 15 builds — flow in US GPM across the top

CRE 20 builds — flow in US GPM across the top

Drawing from a tank, cistern or well — nothing arrives with pressure, so what the system adds is what you get. Read the table straight through: a duplex CRE 15-3 at 200 GPM comes out at 144 ft (62 psi).

Fed by a city main — the system adds on top of what already arrives, and the controller holds the total at the setpoint. With 102 psi wanted at the outlet on a 40 psi main, the duplex CRE 15-3 only has to add 62 psi and delivers about 200 GPM; with 89 psi wanted, it adds 49 psi and delivers about 240 GPM. Incoming pressure buys you more flow, not more pressure — and inlet pressure plus the closed-valve pressure must stay under the 232 psi system rating.

Ask the system for more than it can deliver at your setpoint and all pumps run at full speed continuously, which is where motors and seals wear out. Grundfos also sets a floor: do not run below 10% of one pump's rated flow. Sizing to the building rather than to the headline maximums is what makes it last. Send us the peak flow, the setpoint and the inlet pressure and we will return the build with the manufacturer's curve for it.

Grundfos publishes Hydro Multi-E performance as curve charts, not tables. The figures above are read from those charts (Data Booklet 99347082, 10.2025, printed pages 35 to 37; the charts are also in the image gallery), heads rounded down to the whole foot and psi = ft x 0.433 rounded down; a blank cell means Grundfos does not draw that curve at that flow. The first column is the ceiling at or near zero flow, not a working point. Curves are at a fixed 3,480 rpm, 60 Hz, airless water at 68 °F, ISO 9906:2012 Grade 3B; fitting and valve losses are not included, and Grundfos Product Center, which uses actual motor speed, reads slightly lower at the high-flow end. Grundfos does not publish a best operating range for these systems. Grundfos range maximums: 462 GPM and 475 ft (brochure 11.2025).

Source: Data Booklet 99347082, printed page 13; pump housing per Grundfos Product Center data sheets.

CIM modules fit in the pump terminal box and must be fitted by authorized persons. Tank sizes from the Grundfos price list effective January 1, 2026; CIM part numbers from Data Booklet 99347082, printed page 53.

Hydro Multi-E is set up and run from the advanced operating panel on the master pump, with no app required. Grundfos GO adds guided commissioning, live operating data, alarm troubleshooting and PDF reports on a smartphone. Grundfos lists the MI 301 mobile interface as the accessory for this: it pairs with the phone by Bluetooth and reaches the pumps by radio or infrared. It is sold separately.