JOHNSON CONTROLS
65
SECTION 5 – SEQUENCE OF OPERATION
FORM 100.50-NOM12
ISSUE DATE: 04/02/2019
5
TABLE 22 - SZVAV — CURRENT UNIT MODES
UNIT MODE ZONE TEMPERATURE
Occ Standby
There is no demand for cooling or heating
Supply fan at SZVAV minimum speed if there is a demand for G terminal either from a
thermostat or from the BAS
Supply fan at SZVAV minimum speed if continuous ventilation is User Enabled
Supply fan OFF if continuous ventilation is User Disabled
Occ Cooling Low
Current zone temperature is 0.5°F above the occ/unocc zone cooling setpoint
There is a demand for Y1 terminal either from a thermostat or from the BAS
Supply Fan at SZVAV minimum speed
Occ Cooling High
Current zone temperature is 1.5°F above the occ/unocc zone cooling setpoint
There is a demand for Y2 terminal either from a thermostat or from the BAS
At this point the supply fan speed starts to increase as the cooling demand increases,
and decrease as the cooling demand decreases
1
The supply fan is at 100% when the current zone temperature is above the occ/unocc
zone cooling setpoint by 2.5°F
Occ Heating Low
Current zone temperature is 0.5°F below the occ/unocc zone heating setpoint
There is a demand for W1 terminal either from a thermostat or from the BAS
Supply fan at 100%
Occ Heating High
Current zone temperature is 1.5°F below the occ/unocc zone heating setpoint
There is a demand for W2 terminal either from a thermostat or from the BAS
Supply fan at 100%
Unocc Standby There is no demand for cooling or heating and the supply fan is OFF
Comfort Ventilation Cooling See description in Comfort Ventilation section on page 102
Comfort Ventilation Heating See description in Comfort Ventilation section on page 102
Morning Warm-Up See description in Heating section on page 86
Unocc Cooling Low
Current zone temperature is 0.5°F over the unocc zone cooling setpoint
There is a demand for Y1 terminal either from a thermostat or from the BAS
Supply fan at SZVAV minimum speed
Unocc Cooling High
Current zone temperature is 1.5°F over the unocc zone cooling setpoint
There is a demand for Y2 terminal either from a thermostat or from the BAS
At this point the supply fan speed starts to increase as the cooling demand increases,
and decrease as the cooling demand decreases (see Note at bottom)
The supply fan is at 100% when the current zone temperature is above the unocc zone
cooling setpoint by 2.5°F
Unocc Heating Low
Current zone temperature is 0.5°F under the unocc zone heating setpoint
There is a demand for W1 terminal either from a thermostat or from the BAS
Supply fan at 100%
Unocc Heating High
Current zone temperature is 1.5°F under the unocc zone heating setpoint
There is a demand for W2 terminal either from a thermostat or from the BAS
Supply fan at 100%
NOTE
1. When a SZVAV unit is being controlled by a staged input, a demand for Y2 terminal causes the supply fan to go directly to 100% from
SZVAV minimum speed. There is no modulation as with zone temperature.
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