JOHNSON CONTROLS
69
SECTION 5 – SEQUENCE OF OPERATION
FORM 100.50-NOM12
ISSUE DATE: 04/02/2019
5
TABLE 25 -
SUPPLY FAN SYNC CONTROL
VDC SIGNAL
SUPPLY FAN SPEED
1 VDC
20% at approximately 32hz
2 VDC
40% at approximately 40hz
3 VDC
60% at approximately 46hz
4 VDC
80% at approximately 53hz
5 VDC
100% at approximately 60hz
Johnson Controls recommends installing
the tubing from the duct static pressure
transducer to the proper location in the
unit ductwork. The duct static pressure
transducer provides the only factory in-
stalled duct over pressure device.
Cooling And Heating Operation
•
On a VAV configured unit, cooling and heating
demands in Occ mode are determined by the cur-
rent RAT.
• The IPU board compares the current RAT against
the RAT cooling setpoint and the RAT heating
setpoint to determine when to enter an Active
Cooling or Heating mode.
• If the current RAT remains between the RAT cool-
ing setpoint and the RAT heating setpoint, the unit
remains in Occ Standby.
• RAT cooling setpoint can be found under the
SETPOINTS-COOLING menu.
• RAT heating setpoint can be found under the
SETPOINTS-HEATING menu.
• In Unocc mode, cooling and heating demands is
determined by the current zone temperature.
• Unocc cooling and heating are only allowed
if night set-back is User Enabled. unocc cool-
ing zone setpoint can be found under the SET-
POINTS-COOLING menu.
• Unocc heating zone setpoint can be found under
the SETPOINTS-HEATING menu.
• If the IPU board does not see a valid zone tem-
perature and night set-back is User Enabled, this
creates a fault and causes a unit lockout.
• Night set-back can be found under the PRO-
GRAM-UNIT DATA
menu.
• All setpoints are also available on a BAS.
TABLE 26 -
VAV UNIT MODE
UNIT MODE
ZONE TEMPERATURE
Occ Standby
No demand for cooling or heating exists
Occ Cooling
Current RAT is above the active cooling
RAT setpoint by 0.5°F
Occ Heating
Current RAT is below the active heating
RAT setpoint by 0.5°F
Unocc Standby No demand for cooling or heating exists
Unocc Cooling
Current zone temperature is above the
unocc cooling zone setpoint by 0.5°F
Unocc Heating
Current zone temperature is below the
unocc heating zone setpoint by 0.5°F
Active Supply Air Temperature (SAT) Setpoint
•
Once a VAV configured unit enters an Active
Cooling or Heating mode, the IPU board turns
ON/OFF stages of cooling or heating as needed
to achieve and maintain the active SAT setpoint.
• This includes economizer operation if outside air
conditions are suitable.
Cooling Mode
• In the Cooling mode, the active cooling SAT
setpoint can either be a fixed value or can be reset
be reset using the SAT reset method control logic
built into the IPU board.
Heating Mode
• In the Heating mode, the active heating SAT
setpoint is a fixed value and does not have the abil
-
ity to be reset like the active cooling SAT setpoint.
SAT Reset Method
•
A Series 100 unit configured for VAV operation
has the ability to reset the active cooling SAT
setpoint by using one of four methods. The SAT
reset method can be selected under the
OPTIONS-
UNIT DATA menu.
• Three of the reset methods (RAT, OAT, and sup-
ply fan VFD speed) use internal programming and
logic, return air, outside air, and supply fan speed.
• The fourth method (hardwired) uses a VDC sig-
nal sent from a field installed controller or a com
-
mand from a BAS.
• These four methods, including how they work
and the user adjustable setpoints available, are de-
scribe as follows.