A single duct VAV like the one shown here is one of the most basic air terminal units installed. There is no heat generated from this type of box, it is strictly used for supplying airflow in cooling mode. A maximum and minimum cooling can be set to any desired cfm as long as it is within its design capabilities. This type of box is mostly found in the interiors of a building. The heat generated by lights, equipment, and people usually produce sufficient heating for the interior areas. The following steps should be taken to balance this type of box:
- Drive the VAV box to its maximum cooling design. Some boxes may have to be set to minimum first. See controls operation.
- Measure total airflow by flow hood outlet readings or by pitot tube traverse.
- Adjust box actual airflow to meet the design airflow.
- When design airflow has been calibrated then a grille balance can be done.
- Now drive the VAV box to minimum/maximum and repeat the process.
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