Due to our policy of continuous product innovation, some specifications may change without notification.
LG Electronics U.S.A., Inc., Englewood Cliffs, NJ. All rights reserved. “LG Life’s Good” is a registered trademark of LG Corp.
16
Dedicated Outdoor Air System (DOAS) Installation and Operation Manual
LOW VOLTAGE COMMUNICATIONS
Outdoor/DOAS Unit Communications Cable Installation Guidelines
Outdoor/DOAS Unit Communications Cable Installation Guidelines
Three phase voltage imbalance will cause motor overheating and premature failure. The maximum allowable imbalance is 2.0%. Voltage imbal-
ance is dened as 100 times the maximum deviation from the average voltage divided by the average voltage.
Polarity matters. When connecting the communications cable conductors at each Multi V system component, be careful the conductor
connected to the DOAS (A) terminal on the outdoor unit is connected to the 10 terminals at each AHU control terminal. Likewise, the conduc-
tor connected to the DOAS (B) terminal on the outdoor unit must be connected to the 11 terminals at each AHU control terminal. Cross con-
necting between the “A” and “B” terminals will cause a communications error and the system will not run (see Figure 10).
The minimum distance required between power wires and the communications cable is voltage/amperage dependent and in cases where either
are relatively high the minimum distance may be more than two (2) inches. Refer to the respective LG Multi V Outdoor Unit Engineering Manual
on www.lg-vrf.com for detailed information.
CEN B SODU B
ODU Connected to DOAS Main Coil
CEN A IDU AIDU BSODU ACEN B SODU B
ODU Connected to DOAS Reheat Coil
CEN A IDU AIDU BSODU A
COMM1(2)
COMM2(2)
RS485A(2)
RS485B(2)
COMM1(2)
COMM2(2)
RS485A(2)
RS485B(2)
Figure 10: DOAS Wiring Connection to Outdoor Unit
• Keep communications cables away from line voltage wiring, lighting ballasts, and other devices emitting EMF energy. Maintain a minimum
of two (2) inches between line voltage wires and communications cables.
• Field provide a minimum of 18-4 AWG, stranded and shielded, PVC or vinyl jacket communications wiring between the DOAS units and outdoor units.
• The outdoor/DOAS unit communications cable must be run between components in a daisy chain configuration.
• Ground the shield of the communications cable at the OUTDOOR UNIT END ONLY.
Don’ts
• Star and Wye communications cable configurations are not acceptable
• Never splice communication cables
• Never use wire caps
To Next Page
Loading...
