Page 42
Outdoor Air Damper and Economizer Operation
DIRECT DRIVE DRIVE SYSTEM OPERATION:
Note: Direct drive units feature ECM condenser fans that
are staged to match the compressor’s capacity. The con-
denser fans speed linearly follows the compressor speed.
Modulating Outdoor Air Damper:
Damper minimum positions #1 and 2 are adjusted during
unit setup to provide minimum fresh air requirements at
the indicated supply fan speeds per ASHRAE 62.1.
-Supply fan is on low speed and the outdoor air
damper is at minimum position 1
-Supply fan is on high speed and the outdoor air damp-
er is at minimum position 2
1
Outdoor Air is Suitable
Note: When outdoor air is not suitable during the occu-
pied time period, damper modulates to minimum position.
When outdoor air is not suitable during the unoccupied
time period, damper modulates closed.
1-Economizer With Outdoor Air Suitable
Low Cooling Demand -
Blower Variable
Dampers Modulate
High Cooling Demand -
Compressor Variable
Blower Variable
Dampers Full Open
Note - Compressor is energized after damper has been at
full open for three minutes.
Note - Free cooling is locked out when a dehumidication
demand is received. The unit operates in dehumidication
mode as if the outdoor air is not suitable.
2-No Economizer or Outdoor Air Not Suitable
Any Demand -
Compressor Variable
Blower Variable
Damper Minimum Position
F-Power Exhaust Relay K65 (power exhaust units)
-
energized.
G-Power Exhaust Fans
E1PWRE10A available for LGM 3 and 4 ton units and
instructions for more detail.
P24
J24 JACK ON
INSIDE OF
ECONOMIZER
PANEL
CONNECT P18 TO J18
AND P24 TO J24
BEFORE SECURING
XHAUST FAN IN PLACE
P18
J18 JACK ON
UNDERSIDE OF
DIVISION PANEL
FIGURE 35
H-Optional UVC Lights
The germicidal light emits ultraviolet (UVC) energy that
(viruses, bacteria, yeasts, and molds) in the air.
UVC germicidal lamps greatly reduce the growth and pro-
liferation of mold and other bio-aerosols (bacteria and vi-
ruses) on illuminated surfaces.
Germicidal lamps are NOT intended to be used for remov-
al of active mold growth. Existing mold growth must be
appropriately removed PRIOR to installation of the germi-
cidal lamp.
Refer closely to UVC light installation instruction warnings
when servicing units.
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