Rear Door Heat Exchange
KX-RDHx A90
Active Rear Door Heat Exchanger
Fan-assisted door cooling to 90 kW per rack, with EC fans that modulate on cabinet exhaust temperature.
- Rated capacity
- 90 kW
- Per rack
- 90 kW
- Nominal Delta-T
- 10 K
- Nominal flow
- 129 L/min
- Supply water
- W15 – W30 (15 – 30 °C)
- Max pressure
- 6.0 bar
- Partial PUE
- 1.12
- Working fluid
- Treated water
The A90 is what you fit when the racks have outgrown a passive door but the servers are not ready for cold plates — which describes a great many real deployments sitting between 45 and 90 kW.
Fans that respond to the load
Eight EC fans modulate continuously on measured cabinet exhaust temperature rather than following a fixed speed curve. At part load the door is nearly silent and draws almost nothing; at full load it delivers the airflow the passive coil could not.
Failing in the right direction
Loss of the control signal drives the fans to full speed. Loss of power leaves you with a passive rear door — degraded, but still removing heat from a coil fed by water. There is no failure mode in which the door becomes an obstruction.
Warmer water
Because the fans supply the airflow, the A90 tolerates supply water up to 30 °C where the passive coil wants 25 °C or below. That five kelvin is often exactly what lets a site stay on free cooling through the summer.
Technical data
Full specification
Values are at nominal duty. Ask us for the full performance map if you are working outside these conditions.
| Rated capacity | 90 kW |
|---|---|
| Configuration | Active, EC fan assisted |
| Supply water temperature | 15 – 30 °C |
| Nominal Delta-T | 10 K |
| Nominal flow rate | 129 L/min |
| Fans | 8 × EC, N+1, 0 – 100 % modulation |
| Fan power at duty | 340 W |
| Acoustic level at 1 m | 62 dB(A) |
| Maximum working pressure | 6 bar |
| Electrical supply | 230 V single phase, dual feed |
| Communications | Modbus TCP, SNMP v3 |
| Dimensions (W × H × D) | 600 × 1,995 × 230 mm |
| Mass (dry) | 112 kg |
| Partial PUE contribution | 1.12 |
Module 05 — Flow envelope
Delta-T against required flow
This unit rejects 90 kW. Widening the temperature difference across the loop cuts the volume of water you have to move — and pump power falls with roughly the cube of flow.
- Required flow
- 129 L/min
- Return temperature
- 40.0 °C at W30 supply
- Relative pump power
- 100 % of nominal
Water at 4.18 kJ/kg·K, density taken as 1 kg/L. Pump power index scales with the cube of the flow ratio against this unit’s nominal 10.0 K design point.
Related
Others in this range
KX-RDHx P45
Passive Rear Door Heat Exchanger
A fanless door coil that neutralises up to 45 kW of rack exhaust using only the server fans already in the cabinet.
- Capacity
- 45 kW
- Per rack
- 45 kW
- Delta-T
- 10 K