Local AHU
Local AHU
A local air handling unit works in just the same way as a central air handling unit, except it serves only a single zone and can only be reached from that zone. The heat and air from the unit in the zone is recorded as coming from mechanical ventilation.
A local AHU may be connected as central AHU or as room unit. The main difference is how it which water circuit it is connected to: the AHU circuit or zone circuit. Another difference is how AHU is reported in the Systems energy report: as AHU or as room unit.
A local AHU serves always one zone, even if the zone multiplier in not equal to 1 (it is assumed that every zone of this type has own local AHU).
Table of air handling units
The table of air handling units lists all AHUs connected to zone, both central and local.
Description of columns:
Name | The object name (either a local AHU or a reference to a central AHU) |
Central air handling unit | Choice of a central AHU. Not available for local AHU |
System type | Choice of ventilation strategy (only for first AHU; for additional AHUs only CAV is supported) |
Supply air | Supply air for CAV. Not available for VAV. |
Return air | Return air for CAV. Not available for VAV. |
Return terminal height | The position of the return terminal above the floor. Significant for zone model with temperature gradient only. |
Connected as | Select how the local AHU is connected with plant and how it is reports in Systems energy report. No choice for central AHU. |
An additional air handling unit is introduced in a zone by following the More… link in the Ventilation section of the zone form. Then press Add AHU, and select AHU from list of available units (or just drag from palette). The list consists of 2 sections:
- the list of central AHUs in the building. Use this section to make an additional connection of zone to existing central AHU;
- the list of available AHU types (including user-defined ones). Use this list to insert a new local AHU
Additional AHUs may only operate in CAV, with flows given in the table.