Johnson Controls LSWU035 User Manual

JOHNSON CONTROLS
141
SECTION 5 – SEQUENCE OF OPERATION
FORM 145.05-NOM7
ISSUE DATE: 10/31/2019
5
5. If MX SAT is less than the MX SAT SP minus the
“COOLING CONTROL OFFSET,” the Unit Con-
troller stops a compressor based on the “NEXT
STAGE TO DISABLE”
Occupied Cooling w/ Bypass
1. Unit enters an active COOLING mode
2. Unit Controller sets the “COOLING CONTROL
OFFSET” to 2.0°F
3. Unit Controller compares the Evap Leaving Air
Temp to the active EVAP LEAVING AIR TEMP
SP plus or minus the “COOLING CONTROL
OFFSET”
4. If Evap Leaving Air Temp is greater than the ac-
tive EVAP LEAVING AIR TEMP SP plus the
“COOLING CONTROL OFFSET,” the Unit
Controller:
a. Starts a compressor
OR
b. Commences on an additional stage of cooling
based on the “NEXT STAGE TO ENABLE”
5. If the Evap Leaving Air Temp is less than the
active EVAP LEAVING AIR TEMP SP, the
Unit Controller stops a compressor based on the
“NEXT STAGE TO DISABLE”
FlexSys: Economizer
The suitability requirements are the same as above ex-
cept for
• Normal-Active OAT must be at least 2.0°F below
the MX SAT SP
• Normal-Inactive OAT is greater than/equal to the
MX SAT SP
When conditions are determined suitable for Econo
Operation, the Unit Controller sends a 0–10VDC sig-
nal to the O/A damper actuator, modulating the damp-
ers open/closed. OA dampers are modulated to main-
tain the active MX SAT SP
FlexSys: Heating
OCCUPIED/UNOCCUPIED heating operation fol-
lows the same sequence as a VAV configured unit. It
is recommended to limit the HEATING SAT SP to
80.0°F or 90.0°F. This prevents the underfloor concrete
slab from becoming too warm and radiating heat for
an extended period of time after heating operation has
been terminated.
FlexSys Under Floor Temperature Control
Dew Point Reset
This sequence changes the Active Evaporator Leaving
Air Temperature to a lower value when the temperature
of the underfloor air approaches its dew point.
• MUST have an underoor slab temperature sen-
sor AND an underoor humidity sensor installed.
(Field provided and eld wired to CTB1. Can also
be communicated from the BAS.)
• Dew Point Reset MUST be USER ENABLED
• Unit controller uses the MX SAT and the under-
oor humidity to calculate the underoor dew
point
• If Underoor Air Dew Point ≥ the Underoor
Slab Temp minus 2.0°F for 120 seconds, the Unit
Controller switches from the EVAP LEAVING
AIR TEMP HIGH SP to the EVAP LEAVING
AIR TEMP LOW SP
• The Unit Controller continues to use the EVAP
LEAVING AIR TEMP LOW SP until the
Underoor Air Dew Point < the Underoor Slab
Temp minus 2.5°F
Active Slab Control
This sequence allows heat to be turned ON during a
transition from one occupancy state to another if the
Underfloor Air Temperature is higher than the Unde-
floor Slab Temp.
• Unit MUST have heat installed
• Heating System MUST be USER ENABLED
• Active Slab Control MUST be USER ENABLED

Johnson Controls LSWU035 Specifications

General

Brand	Johnson Controls
Model	LSWU035
Category	Chiller
Language	English