Server rooms reject enormous, constant heat. An energy recovery wheel between the exhaust and make-up air streams cuts the cooling load and can redirect that warmth to heat adjacent office space. For data centers chasing PUE, recovery on the ventilation air is a straightforward win.
The load you can recover
IT power is almost entirely converted to heat. Roughly 1 kW of IT equipment rejects ~1 kW of heat. A modest hall of 100 racks at 5 kW each rejects about 500 kW — most of it carried away by the cooling and ventilation air, not the servers themselves.
- Make-up air: data centers bring in outdoor air for pressurisation and free cooling.
- Exhaust: the return airstream leaves warm and, in free-cooling mode, directly to atmosphere.
- The gap: an energy wheel bridges those two streams.
Rotary wheel vs run-around coil
| Option | Effectiveness | Notes |
|---|---|---|
| Rotary energy wheel | 70–85% (total) | Compact, recovers humidity too; needs purge for separation |
| Run-around coil | 40–60% (sensible) | No air mixing; pump + piping; good where streams are distant |
| Plate exchanger | 60–75% (sensible) | No moving parts; simpler but larger footprint |
For tight plant rooms a rotary wheel is the most effective choice; a plate or run-around coil is preferred where the design forbids any chance of exhaust-to-supply mixing.
Where the recovered heat goes
- Reheat for VAV terminal boxes in adjacent offices.
- Preheat of outdoor air for the building HVAC.
- Domestic water pre-heat in larger campuses.
Pair the recovery with our sizing guide and the kitchen recovery playbook — the airflow and temperature logic is the same.
Sizing recovery for a data hall?
EN159 builds plate, rotary, heat-pipe and counterflow air-to-air exchangers for data-center make-up and exhaust air. Send airflow (m³/h), supply and exhaust temperatures and the available footprint.
Related reading
Heat Recovery Units ·
Commercial Kitchen Heat Recovery ·
Plate Heat Exchanger Guide
Frequently Asked Questions
How much heat can a data center recovery wheel realistically reclaim?
In a data hall nearly all IT power becomes heat, so a rotary wheel rated 70 to 85 percent total effectiveness can return a large share of the ventilation energy to adjacent loads such as VAV reheat or make-up air preheat. Actual savings scale with airflow and the winter temperature lift.
Will a rotary wheel mix exhaust air back into the supply?
A properly specified wheel includes a purge sector that scavenges residual exhaust from the matrix before it reaches the supply sector, keeping cross-leakage very small. Where any mixing is unacceptable, a plate or run-around coil provides complete stream separation.
Where does the recovered data center heat usually go?
Common sinks are reheat for VAV terminal boxes in adjacent office space, preheat of outdoor air for the building HVAC, and domestic water pre-heat on larger campuses. Pairing recovery with the site existing sizing logic keeps the integration straightforward.
Is a rotary wheel or a run-around coil better for a tight plant room?
A rotary wheel is the most compact option and also recovers humidity, which helps in humid climates. A run-around coil is preferred when ducts are far apart or when the design forbids any chance of exhaust-to-supply mixing.
Specify the right heat exchanger
Our engineers size the core to your airflow, temperature and pressure-drop budget, and select plate, rotary or heat-pipe recovery by application. Read the heat exchanger guide or contact us for a specification.
Related products
Plate, wheel or pipe recovery for HVAC and ventilation.
Stationary, high-surface-area cores for air and liquid.
High-effectiveness energy recovery for large airflows.
Passive, fully separated streams for clean applications.