Constant Air Volume Box

The constant air volume (CAV) box is an air terminal without turndown on an air system. It typically contains a reheat coil, but this is optional.

Required Objects

The CAV box must have the following properties.

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

Design Assumptions

The air flow is used for the sensible peak on a traditional air system, and only for ventilation in 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

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 hot water coil is used in the system.
Hot water design outlet temperature	N/A	Set by the hot water loop if hot water coil is used in the system.