Airflow limits for critical spaces

Supply Air Flow Limits for Air Terminals - Configuration

The Supply Air Flow serves multiple functions: heating, cooling, ventilation, and pressurization. The following section explains how to configure each supply terminal for different use cases.

	Cooling	Heating	Ventilation
Single CV (Constant Volume) Supply Terminal	Min = Max = 0 (or minimum flow value needed for the coil to cool the room)	Min = Max = 0 (or minimum flow value needed for the coil to heat the room)	Min = 0 Max ≥ The largest value configured in Ventilation AF
Single VAV (Variable Air Volume) Supply Terminal (no fume hood)	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min = 0 Max Ventilation ≥ Largest value configured in Ventilation AF
Single VAV Supply Terminal (fume hood)	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min Ventilation = 0 Max Ventilation ≥ Largest value configured in Ventilation AF or value needed to balance maximum fume hood flow

Check the project specification to see if the various terminals are to be sequenced differently from each other: if they respond to different needs. If no difference is specified, follow the next table's instruction. If the flow limits are set the same for each terminal, then they run at equal flows.

	Cooling	Heating	Ventilation
Multiple Supply Terminals (same size, same function)	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule (specified per terminal)	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min = 0 Max ≥ The largest of configured ventilation levels for the room and the supply flow needed to balance fume hoods, divided by the number of supply terminals

Check the project specification to see if the various terminals are to be sequenced differently from each other: if they respond to different needs. If the supply terminals are different sizes but have the same function, follow the next table's instruction.

	Cooling	Heating	Ventilation
Multiple Supply Terminals (different sizes, same function)	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule (specified per terminal)	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min = 0 Max ≥ 1. The largest value of the terminal being configured or 2. The value needed to balance maximum fume hood flow of the terminal being configured

In the case of multiple supply terminals with different functions, the following tables provide an example of how to configure one CV (Constant Volume) Terminal serving a chilled beam, and one VAV (Variable Air Volume) Terminal without cooling.

Flow through the CV Terminal does not vary to heat or cool.
Flow is always set by ventilation or support for coil (minimum heat or minimum cooling) unless reducing it is the only way to maintain room pressurization.

Flow through the VAV Terminal may vary for heating, cooling, and ventilation, or to balance fume hood flow.

	Cooling	Heating	Ventilation
Multiple Supply Terminals (different functions) CV Terminal	Min = Max = 0 (or minimum flow value needed for the coil to cool the room)	Min = Max = 0 (or minimum flow value needed for the coil to heat the room)	Min = Max = 0 (or value needed to support a heating or cooling coil)
Multiple Supply Terminals (different function) VAV Terminal	Min = 0 (or minimum flow value needed for the coil to cool the room) Max = Value from box schedule (specified per terminal)	Min = 0 (or minimum flow value needed for the coil to heat the room) Max = Min (if sequence does not vary flow to heat) If sequence does vary flow to heat: Max = Value from box schedule	Min = 0 Max ≥ 1. The largest value of the terminal being configured or 2. The value needed to balance maximum fume hood flow of the terminal being configured