2.1.1 An example and further explanation for CP7 and HP6 profiles

As we have separate controllers for VAV heating and cooling airflow, the value in these controllers during occupied hours is always the midpoint between heating and cooling setpoints. If the setpoints are 69°F and 75°F, respectively, then the daytime profile values will be 72°F for both CP7 and HP6.

During night/unoccupied hours/days, these on-off setpoint control profiles operate the VAV airflow ON only when the temperature in at least one zone is either below the Heating SP +2°F or greater than the Cooling SP -1°F. Thus during the "closed" hours, if there are setpoints as above and heating and cooling setback values of 60°F and 80°F, respectively, the actual deadband in which there will be zero VAV airflow would be 17°F—i.e., the difference between (60+2) and (80-1).

When there is fan cycling, there is effectively a large deadband of no fan operation between the setback values for HP6 and CP7. The alternative to fan cycling in the closed hours is that the fans are on continuously. This is the case for the "Temp setback w OA/off" setback strategy.

When fan cycling is not part of the strategy, the HP6 and CP7 profiles for VAV systems are used to force the VAV boxes to operate and demand at least their minimum flow rate at all times. Thus the value in the profile goes flat at the midpoint between heating and cooling setpoints. The two controllers still hand off control as room temperature passes this mark, but both are giving an ON signal, so the effect is a continuous flow at least equal to the min VAV flow rate.