Table of Contents
RDHX is designed to complement new and existing data centers, enabling increased computing capacity without adding to the heat load in the room.
HPE Rear Door Heat Exchanger (RDHX) is a liquid-to-air heat exchanger cooling system that removes high levels of heat generated by today’s servers, mass storage, and core networking hardware. It is mounted directly to the rear panel of HPE racks. RDHX is compatible with 42U or 48U racks with a range of IT capacity when used under certain load and site conditions.
Overview
RDHX airflow fully supports industry-standard front-to-back cooling designs and standard server dimensions. Cooling coils in the RDHX cool the hot air that exits the rear of the servers, neutralizing the heat before the air returns to the room. Depending on the data center room’s dew point temperature, the RDHX can connect directly to the facility water supply or to a cooling distribution unit (CDU). Top-feed and bottom-feed liquid options are supported. Mural graphics on the doors are also supported. The RDHX can also be deployed with direct liquid cooling (DLC) to increase the percentage of heat captured by water and meet room-neutral requirements.
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RDHX with 42U or 48U Rack Options
Standard Features
Key Features
General Solution
- – Liquid-to-air heat exchanger cooling system attached to the back of a standard IT rack
- – Hot air exhaust from the server moves through cooling coils to remove the heat
Cooling capacity (kW per rack) *
- – M12: 14-35 kW
- – M14: 35-55 kW
Notes: *See the RDHX Site Planning Guide for additional information and specifications
Water
- – Accommodates facility water temperatures 2°C (4°F) above the maximum anticipated dew point
- – Accommodates water pressure between 25 and 100 psi (172 – 689 kPa)
- – For water temperatures at or below the dew point, a Cooling Distribution Unit (CDU) will be required to create a secondary warmer water loop to supply the doors
Power
- – Input power support for 208V / 230V / 277V (1-phase)
Flexibility
- – HPE 42U and 48U racks support shipment of fully integrated IT solutions through HPE Factory Express or partner rack integration because the racks are delivered on shock pallets.
- – Underfloor and overhead plumbing capabilities
- – Full services offering available, including planning, deployment, and maintenance
Agency Certifications
- – ETL, CSA, and CE certified
Configuration Information
Each RDHX SKU includes
| |
| For 42U 600 mm HPE G2 Racks (P9K10A) and Heavy Rack (R4L97A) | SKU |
| HPE M12 42U 600mm G2 Rack 208–230 V Top Feed Rear Door Heat Exchanger | S4M97A |
| HPE M14 42U 600mm G2 Rack 208–230 V Top Feed Rear Door Heat Exchanger | S4M98A |
| HPE M12 42U 600mm G2 Rack 208–230 V Bottom Feed Rear Door Heat Exchanger | S4M99A |
| HPE M14 42U 600mm G2 Rack 208–230 V Bottom Feed Rear Door Heat Exchanger | S4N00A |
| HPE M14 42U 600mm G2 Rack 260–290 V Top Feed Rear Door Heat Exchanger | S4N01A |
| HPE M14 42U 600mm G2 Rack 260–290 V Bottom Feed Rear Door Heat Exchanger | S4N02A |
| For 42U 800 mm HPE G2 Racks (P9K48A) and Heavy Rack (R4M95A) | SKU |
| HPE M12 42U 800mm G2 Rack 208-230 V Top Feed Rear Door Heat Exchanger | S4N03A |
| HPE M14 42U 800mm G2 Rack 208-230 V Top Feed Rear Door Heat Exchanger | S4N04A |
| HPE M12 42U 800mm G2 Rack 208-230 V Bottom Feed Rear Door Heat Exchanger | S4N05A |
| HPE M14 42U 800mm G2 Rack 208-230 V Bottom Feed Rear Door Heat Exchanger | S4N06A |
| HPE M14 42U 800mm G2 Rack 260-290 V Top Feed Rear Door Heat Exchanger | S4N07A |
| HPE M14 42U 800mm G2 Rack 260-290 V Bottom Feed Rear Door Heat Exchanger | S4N08A |
| For 48U 600 mm HPE G2 Racks (Rack SKU P9K52A) | SKU |
| HPE M12 48U 600mm G2 Rack 208–230 V Top Feed Rear Door Heat Exchanger | S4N09A |
| HPE M14 48U 600mm G2 Rack 208–230 V Top Feed Rear Door Heat Exchanger | S4N10A |
| HPE M12 48U 600mm G2 Rack 208–230 V Bottom Feed Rear Door Heat Exchanger | S4N11A |
| HPE M14 48U 600mm G2 Rack 208–230 V Bottom Feed Rear Door Heat Exchanger | S4N12A |
| HPE M14 48U 600mm G2 Rack 260–290 V Top Feed Rear Door Heat Exchanger | S4N13A |
| HPE M14 48U 600mm G2 Rack 260–290 V Bottom Feed Rear Door Heat Exchanger | S4N14A |
| For 48U 800 mm HPE G2 Racks (Rack SKU P9K58A) | SKU |
| HPE M12 48U 800mm G2 Rack 208–230 V Top Feed Rear Door Heat Exchanger | S4N15A |
| HPE M14 48U 800mm G2 Rack 208–230 V Top Feed Rear Door Heat Exchanger | S4N16A |
| HPE M12 48U 800mm G2 Rack 208–230 V Bottom Feed Rear Door Heat Exchanger | S4N17A |
| HPE M14 48U 800mm G2 Rack 208–230 V Bottom Feed Rear Door Heat Exchanger | S4N18A |
| HPE M14 48U 800mm G2 Rack 260–290 V Top Feed Rear Door Heat Exchanger | S4N19A |
| HPE M14 48U 800mm G2 Rack 260–290 V Bottom Feed Rear Door Heat Exchanger | S4N20A |
| Hose Kits for RDHX | SKU |
| HPE QD to TC 1.8 m Hose Pair for Liquid Cooled Door | R4N58A |
| HPE QD to TC 2.4 m Hose Pair for Liquid Cooled Door | R4N59A |
| HPE QD to TC 3 m Hose Pair for Liquid Cooled Door | R4N60A |
| HPE QD to TC 3.7 m Hose Pair for Liquid Cooled Door | R4N61A |
| HPE QD to TC 4.3 m Hose Pair for Liquid Cooled Door | R4N62A |
| US facility adapter for RDHX (only for sites that require an NPT thread) | SKU |
| HPE Cray Supercomputing 25.4mm H2O Adapter NPT Assembly | R6W44A |
| International Facility Adapter for RDHX (Only International Sites That Require BSPT Thread) | SKU |
| HPE Cray Supercomputer 25.4mm Water Adapter BSPT Kit | S0B09A |
| Notes: One hose kit SKU and one facility adapter SKU are required for each door ordered. | |
| 270 kW CDU for RDHX - USA Voltage | SKU |
| HPE Cray Supercomputer 3-phase 270 kW 208 V 60 Hz 63.5 mm NA Floor Coolant Distribution Unit | R4N53A |
| HPE Cray Supercomputer 3-phase 270 kW 480 V 60 Hz 63.5 mm NA Floor Coolant Distribution Unit | R4N56A |
| 270kW CDU for RDHX - EU Voltage CDU for RDHX | SKU |
| HPE Cray Supercomputer 3-phase 270kW 400V 50Hz 63.5 mm EU Floor Coolant Distribution Unit | R9B19A |
| USA Facility Adapter RDHX CDU | SKU |
| HPE Cray Supercomputing 76.2 mm H2O Adapter NPT Assembly | R6T83A |
| International facility adapter for the RDHX CDU (only for sites that require a BSPT thread) | SKU |
| HPE Cray Supercomputer 76.2mm Water Adapter BSPT Assembly | S0B12A |
| Notes: – One facility adapter SKU, either R6T83A or S0B12A, is required for each CDU ordered. – A CDU is required for sites that have supply water temperature at or below dew point. – The CDUs include a primary hose kit, secondary manifold, and treated water for the secondary cooling loop to the RDHXs. – HPE-provided secondary manifold is designed for raised floor data centers. If the data center is on a concrete slab, the customer is required to provide the overhead secondary manifold that feeds from the CDU to the RDHXs. – Consult Site Engineering when planning to use a CDU or when CDU requirements are unclear. | |
Service and Support
For the most up-to-date information on HPE Services, please refer to the HPE Services – Supplemental QuickSpecs, which provides a comprehensive and regularly updated overview of available services.
Technical Specifications
Environment-friendly products and approach: End-of-life management and recycling
Hewlett Packard Enterprise offers end-of-life product return, trade-in, and recycling programs, in many geographic areas, for our products. Products returned to Hewlett Packard Enterprise will be recycled, recovered, or disposed of in a responsible manner.
The EU WEEE Directive (2012/19/EU) requires manufacturers to provide treatment information for each product type for use by treatment facilities. This information (product disassembly instructions) is posted on the Hewlett Packard Enterprise website.
These instructions may be used by recyclers and other WEEE treatment facilities as well as Hewlett Packard Enterprise OEM customers who integrate and resell Hewlett Packard Enterprise equipment.
Summary of Changes
| Date | Version History | Action | Description of Change |
|---|---|---|---|
| 21-Sep-2026 | Changed | Replaced references to "HPE GreenLake" with "GreenLake" to align with current branding standards. | |
| 06-Jul-2026 | Changed | Updated the configuration information, product options, technical specifications, and related document formatting. | |
| Updated the “Each RDHX SKU includes” section and associated configuration information to standardize water adapter and facility adapter options. | |||
| 02-Feb-2026 | Changed | The Configuration Information section was updated. | |
| 14-Apr-2025 | Changed | The Configuration Information section was updated. | |
| 04-Nov-2024 | New | New QuickSpecs. |
© Copyright 2026 Hewlett Packard Enterprise Development LP. The information contained herein is subject to change without notice. The only warranties for Hewlett Packard Enterprise products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. Hewlett Packard Enterprise shall not be liable for technical or editorial errors or omissions contained herein.
a00039574enw, - 16140 - Worldwide - V5 - 21-September-2026