JOHNSON CONTROLS
21
FORM 100.50-SU8
ISSUE DATE:1/28/2016
7
The Series 100 with the IPU controller has the abil-
ity to operate as a Single Zone VAV unit. This is only
available with units that have the below software ver-
sions:
1. 50-61 tons “Rev F”: C.LCR.02.05
2. 70-150 tons “Rev F and G”: C.ECO.01.13
On units with older versions of software, it may be pos-
sible to upgrade the software and then configure the
unit for Single Zone VAV operation. A supply fan VFD
is required for single zone VAV operation.
WHAT IS SINGLE ZONE VAV?
Single Zone VAV (SZVAV) is typically defined as a
ducted HVAC system connected to a rooftop unit with
no VAV boxes installed in the duct system. This type of
system is typically controlled by one temperature input
to the rooftop unit.
On previous versions of the Series 100 units, the only
unit types were Constant Volume (CV), Variable Air
Volume (VAV), or Flexsys. A CV unit had a single
speed supply fan with no way to raise or lower the
speed. A VAV- or Flexsys-configured unit had supply
fan variable frequency drives (VFDs) installed. The
supply fan VFDs were controlled by the duct static
pressure setpoint (SP). The VFDs would ramp up/
down to maintain the active duct static pressure SP. CV
units rely on thermostat commands or a zone tempera-
ture input to determine the active mode of operation.
VAV or Flexsys units rely on the return air temperature
to determine the active mode of operation.
On a Series 100 unit configured for Single Zone VAV,
the active mode of operation will be determined by a
zone temperature input to the IPU controller, either
hardwired or communicated from the BAS. The speed
of the supply fan VFD will be controlled as below:
Single Zone VAV Minimum Fan Speed
• This is a user adjustable SP. The range is 33–66%.
The factory default is 50%.
• Bacnet Point: SZ_MIN_VFD (AV53)
MODES OF OPERATION
Occupied Standby
• Supply fan will run at the SZVAV min speed
• Must be commanded on by FAN_G_BAS (AV82
or BV06) OR Continuous Ventilation is User En-
abled. Continuous Ventilation can be enabled at
the unit controller or through the BAS.
• CONTINU_VENT (AV79 or BV03)
Occupied Cooling Low
• Zone temp is between 0.5 and 1.5 °F higher than
the zone temperature SP, supply fan at SZVAV
min speed
• The unit controller will utilize as many or as few
stages of cooling that it needs to achieve and main-
tain the 1st Stage Cooling SP (STG_1_COOL:
AV31)
Occupied Cooling High
• Zone temp is more than 1.5 °F above zone tem-
perature SP
• The supply fan speed will increase proportion-
ally from the SZVAV min speed SP to 100% fan
speed. When the current zone temp is 2.5 °F or
more above the zone temp SP, the supply fan will
be at 100% fan speed.
• The unit controller will utilize as many or as few
stages of cooling that it needs to achieve and main-
tain the 2nd Stage Cooling SP (STG_2_COOL:
AV33)
Occupied Heating Low
• Supply fan at 100% fan speed
• The unit controller will utilize as many or as few
stages of heat that it needs to achieve and maintain
the 1st Stage Heating SP (STG_1_HEAT: AV32)
Occupied Heating High
• Supply fan at 100% fan speed
• The unit controller will utilize as many or as few
stages of heat that it needs to achieve and main-
tain the 2nd Stage Heating SP ( STG_2_HEAT:
AV34)
SECTION 7 - SINGLE ZONE VAV OPERATION
To Next Page
Loading...
Need help?
General
