JOHNSON CONTROLS
85
SECTION 5 – SEQUENCE OF OPERATION
FORM 100.50-NOM12
ISSUE DATE: 04/02/2019
5
LD28123
FIGURE 44 - CONDENSER FAN VFD WIRING —
CONDENSER FAN 1A SHOWN
Low Ambient Kit
• The Series 100 units can have an optional factory
installed low ambient kit on the compressor cir-
cuits.
• Each compressor circuit can have a low ambient
kit, but the kits are installed in numerical order:
• One kit: Circuit 1
• Two kits: Circuit 1 and 2
• Three kits: Circuit 1, 2, and 3
• A low ambient kit includes a discharge pressure
transducer and condenser fan VFD.
• The condenser fan VFD is a JCI VFD68.
• The VFD68 is not controlled by the IPU board.
The 0–5 VDC signal from the discharge pressure
transducer controls the VFD68.
• The VFD starts to operate condenser fan A at 15
hz at approximately 270 psig and is at 60 hz when
the discharge pressure is at approximately 370
psig.
ECONOMIZER
• The Series 100 unit can be ordered with an op-
tional factory installed economizer.
• An economizer provides free cooling during times
when the OAT is too cold for mechanical cooling
(50.0°F or less without low ambient package).
• The economizer sequence is a completely differ-
ent sequence than ventilation even though both
use the outside air damper.
• The unit must be in an Active Cooling mode for
the economizer to become active.
• There are three different economizer types:
1. Dry Bulb: Economizer suitability determined
by OAT only
2. Single Enthalpy: Economizer suitability de-
termined by OAT and outside air relative hu-
midity
3. Dual Enthalpy: Economizer suitability deter-
mined by comparing the OAT and relative hu-
midity against the RAT and relative humidity
• The Series 100 also has an option for economizer
operation called Best Method. Best method op-
eration is explained in the Best Method section on
page 86.
Economizer Setup
• Economizer Installed must be set in the OP-
TIONS-ECONOMIZER menu.
• Economizer System must be User Enabled in the
PROGRAM-ECONOMIZER menu.
• Economizer Method to Use must be set in the
PROGRAM-ECONOMIZER menu.
Economizer Operation
• The unit must be in an Active Cooling mode for
the economizer to function.
• The economizer can override the maximum
damper position/outside airow setpoint of the
ventilation type if more outside air is needed to
achieve the active cooling SAT setpoint.
• The economizer cannot override the minimum
damper position/outside airow setpoint of the
ventilation type.
• The unit can have economizer operation and me-
chanical cooling operation at the same time if out-
side air conditions are suitable.
Dry Bulb
• Economizer type is dry bulb.
• Economizer is User Enabled.
• The IPU board must see a valid OAT.
• When the current OAT is 2.0°F less than the out-
side air dry bulb setpoint, the economizer be-
comes active.
• The IPU board modulates the outside air damper
to try to achieve and maintain the active cooling
SAT setpoint.
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