return fan

return fan

A fan that removes air from an air-conditioned space.
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A bin temperature method was used to estimate annual energy savings, which include sperate calculations for heating energy, cooling energy, AHU supply fan energy and return fan energy.
The Cavaliers have agreed to a trade with Milwaukee that will return fan favorite Matthew Dellavedova to Cleveland along with forward John Henson and a pair of draft picks in 2021.
If it has a return fan that is controlled by airflow tracking, (4) control the fan with zero offset.
All SDVAV AHUs in building A, B, C have return fan VFD tracking the speed of supply fans.
* The ability to monitor all digital inputs such as damper-receipt proof contacts, safeties, or supply-fan run interlocks to the return fan over the building automation system through the VFDs I/O.
The return fan speed is controlled to maintain the differential airflow rate between the supply and return fans at a set point, which is determined by the required building static pressure (Taylor 2014).
Either way, the return airflow rate is determined by the return air MW boxes, not directly by the return fan, similar to a VAV supply air system.
"This is like keeping your accelerator to the floor when driving your car, while using the brake to stay within the speed limit; you are using more energy than you need," said Kirkendoll, who recommended replacing the existing return fan motors and air dampers with 30- and 40- hp Baldor Super-E motors, rated at 460 volts, with variable-frequency drives, in September 2000.
For Return Fan systems using Direct Pressure control, the sequence is the same except the relief damper is controlled independently off of building pressure.
Figure 1 shows a typical VAV system with a return fan using Airflow Tracking (aka volumetric fan tracking) controls.
3 Return fan fault 08/22 Return fan fixed at 30% speed - half normal speed.
The assumption that energy recovery will add significant static pressure to the supply fan leads some to consider using a return fan system (System C) to off load some of this static pressure.