Trane TRG-TRC014-EN System Configurations, period three, VAV Reheat, heat loss 250 Btu/hr/ft

period three

System Configurations

notes

VAV Reheat

heat loss < 250 Btu/hr/ft

[240 W/m]

VAV reheat terminal unit

Figure 60

When overhead heating is acceptable, VAV reheat, fan-powered, or dual-duct terminal units can be used to provide both perimeter cooling and heating.

In cooling mode, the VAV reheat terminal unit modulates in response to the changing space cooling load, always maintaining a minimum airflow to serve ventilation requirements. For space loads below this minimum airflow, the unit maintains this constant minimum airflow and modulates the reheat coil capacity to satisfy the space tempering or heating requirements.

Reheating previously-cooled primary air is not energy efficient. However, because the VAV system has already reduced the supply airflow, it must reheat only a limited amount of air. The VAV reheat system is far more energy efficient than a similarly-applied, constant-volume reheat system.

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