JOHNSON CONTROLS
66
FORM 100.50-NOM12
ISSUE DATE: 04/02/2019
SECTION 5 – SEQUENCE OF OPERATION
TABLE 23 -
SZVAV — SUPPLY AIR TEMPERATURE (SAT) SETPOINTS
UNIT MODE
SETPOINTS
Occ Standby
There is no demand for cooling or heating
Occ Cooling Low
Active SAT cooling setpoint is the 1st stage cooling setpoint
Occ Cooling High
Active SAT cooling setpoint is the 2nd stage cooling setpoint
Occ Heating Low
Active SAT heating setpoint is the 1st stage heating setpoint
Occ Heating High
Active SAT heating setpoint is the 2nd stage heating setpoint
Unocc Standby
There is no demand for cooling or heating, and supply fan is OFF
Unocc Cooling Low
Active SAT setpoint is the 1st stage cooling setpoint
Unocc Cooling High
Active SAT setpoint is the 2nd stage cooling setpoint
Unocc Heating Low
Active SAT setpoint is the 1st stage heating setpoint
Unocc Heating High
Active SAT setpoint is the 2nd stage heating setpoint
LD28115
FIGURE 26 -
SINGLE ZONE VAV (SZVAV) AND CONSTANT VOLUME (CV) — OCCUPIED AND UNOCCUPIED
VARIABLE AIR VOLUME (VAV)
• An HVAC system that has VAV boxes installed in
the ductwork operates as VAV. Typical VAV sys-
tems have overhead ductwork that provides condi-
tioned air down into the space.
• A VAV unit has a supply fan controlled by a VFD
that is capable of running at different speeds to
maintain a constant duct static pressure.
• The VFD speed is controlled by a duct static pres-
sure transducer that also provides high duct static
pressure protection.
VAV Setup
• Unit type must be set to VAV in the OPTIONS-
UNIT DATA menu.
• Duct static low and high setpoints must be set in
the SETPOINTS-SUPPLY SYSTEM menu.
•
Unit design airflow must be set in the SET
-
POINTS-UNIT DATA menu.
• Return air temperature (RAT) cooling setpoint
must be set in the SETPOINTS-COOLING menu.
• SAT low and high setpoints must be set in the
SETPOINTS-COOLING menu.