Variable Air Volume Box

The variable air volume (VAV) box is an air terminal with turndown on an air system. As an option, it may contain a reheat coil.

Required Objects

The variable air volume box must have the following properties.

• It must be attached to an air system.
• It must be attached to a conditioned zone.

Design Assumption

• The air flow is sized for the sensible peak on a traditional air system and ventilation only for a dedicated outdoor air system (DOAS).

Property	Value	Notes
Cooling supply air temperature	N/A	Determined by the air system (typically 12.7778°C).
Heating supply air temperature	40°C
Minimum air flow fraction	0.3

Reheat Coil

The reheat coil has the following assumptions.

• The electric resistance reheat coil is 100% efficient.
• The furnace reheat coil is 80% efficient.
• The hot water reheat coil has the following properties.

Property	Value	Notes
Coil entering air temperature	Varied	Determined by the air system (typically between 12.7778°C and 18.3333°C by default).
Coil leaving air temperature	40°C
Hot water design inlet temperature	N/A	Set by the hot water loop if a hot water coil is used in the system.
Hot water design outlet temperature	N/A	Set by the hot water loop if a hot water coil is used in the system.