Economizer Start-Up - Lennox LCH036 Installation Instructions Manual

Economizer Start-Up

The economizer is controlled by the Unit Controller which is
located in the control box; see Parts Arrangement in the
front of this manual. A detailed menu layout can be found in
the Unit Controller manual provided with each unit.
A-Free Cooling Mode and Setpoint
On start-up, the economizer mode defaults to TEMP
OFFSET. In this mode, free cooling is energized when the
outdoor air temperature (RT17) is less than return air
temperature (RT16) by at least the offset value. The default
offset value is 10°F. Use the following menu path on the Unit
Controller to adjust the free cooling mode or setpoint. See
figure 37 and 38 for sensor location.
Settings / Setpoints / Damper / Economizer Mode
Refer to table 20 and figure 36 for additional free cooling
modes and setpoints. The Unit Controller has a restricted
range of input values for each mode as shown in table 20.
Note - An energy management system may be used to
provide the outdoor air suitable (OAS) signal via network
connection. The free cooling mode must be set to one of the
TEMP modes to allow this function.
B-California Title 24 Compliance
For California Title 24 compliance, adjust the free cooling
setpoint based on:
-The climate zone where the unit is installed. See table 21.
-The setpoint requirement published by the California
Energy Commission. See Section 140.4 - Prescriptive
Requirements for Space Conditioning Systems of the
2013 Building Energy Efficiency Standards.
Note - Values in the referenced standard will supersede
values listed in table 21.
SETPOINTS
DAMPER
ECONOMIZER
MODE
Use
arrows
to
move
SUPPLY AIR STPT
MIN OCP BLOWER LOW
MIN OCP BLOWER HIGH
RT16 AND RT17 SENSORS
RT17
OUTDOOR AIR
SENSOR
(access through
the control area)
FIGURE 37
Page 38
PARTIAL VIEW OF UNIT CONTROLLER MENU
CON­
OFF­
TEMP
TROL
SET
OAT
STPT
CON­
DIFF
ENTH
Use
TROL
OFFSET
arrows
ODE
to
STPT
move
! SET !
GLOBAL
XX.XºF [44.9 TO 65.3ºF]
XXX% [0 TO 100%}
XXX% [0 TO 100%]
FIGURE 36
LGH/LCH420, 480, 540, 600
XXºF ! SET !
XXºF ! SET !
XX.X
! SET !
MA
XX.X
! SET !
MA
! SET !
! SET !
! SET !
RT16
RETURN
AIR SENSOR