[SP_SPLY] Determination of setpoint supply air

The input control action for energy recovery [ActgErc] expects information for the operating mode of the energy recovery unit: Heating or cooling. When the energy recovery unit is operating in heating mode, it requires a setpoint for heating and in operating mode cooling, a setpoint for cooling. Based on the value from input [ActgErc], SP_SPLY provides either the value from [SpHiSuIn] or [SpLoSuIn] on output [SpErcSu].

In some cases, the energy recovery unit works with the average value of [SpHiSuIn] and [SpLoSuIn]. In these cases, the input selection of energy recovery setpoint [SelSpErc] is used to indicated whether the average value on output [SpErcSu] is provided or not. [SelSpErc] = 1 means that the average value on output [SpErcSu] is used.

Enable and disable function block

If SP_SPLY [EnFnct] = 0 is disabled, the output:

• [SpLoSu] is set to the value form [SpMinSu]
• [SpHiSu] is set to the value from [SpMaxSu]
• [SpErcSu] is set with the average of inputs [SpHiSuIn] and [SpLoSuIn]

If SP_SPLY is enabled [EnFnct] = 1, SP_SPLY provides to outputs [SpHiSu] and [SpLoSu] the values of the corresponding inputs [SpHiSuIn] and [SpLoSuIn]. The value at output [SpErcSu] is determined by inputs [ActgErc] and [SelSpErc]. All output values are limited by the range as defined by [SpMinSu] and [SpMaxSu].

Replace supply air setpoints at outputs

You can override the functionality of SP_SPLY for commissioning, testing, and servicing by setting value 1 on input [EnSbstVal]. In these cases, outputs [SpHiSu], [SpErcSu] and [SpLoSu] are set with the same value. The value can be configured on input [SbstVal]. If [EnSbstVal] = 1, the restriction of [SpMinSu] and [SpMaxSu] are not considered on the function block.