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. |