LENNOX LGH Power Exhaust Fans Instruction Manual

June 4, 2024
Lennox

PACKAGED UNITS KITS AND ACCESSORIES
506745-04 5/2022
Supersedes 12/2020
POWER EXHAUST FANS
INSTALLATION INSTRUCTIONS FOR POWER EXHAUST FANS

USED WITH KG/KC/KH/LG/LC/LH/LD 024-090 PACKAGED UNITS

Shipping and Packing List

Package 1 contains:

  1. Power exhaust assembly
  2. GED Seal
  3.  Bag assembly containing:
  4. 10 Sheet metal screws

  5. 1-Pink wire (K1-1)
  6. 1-Gray wire (K1-2)
  7. 2-Terminal adapters

Check the packaging for shipping damage. Contact the last carrier immediately if any shipping damage is found.

Application

Power exhaust fans are applied to units equipped with an economizer in downflow air discharge. The power exhaust fan option cannot be used in horizontal air discharge applications. See table 1.
Locate all other accessories to be installed. Install accessories in the following order:

  1. -Economizer Dampers
  2. -Sensors
  3. -Power Exhaust Fans
  4. -Hood assembly
  5. -Gravity Exhaust Dampers

TABLE 1

Unit| Unit Voltage| Cat No.| Assembly
No.
---|---|---|---
LG/LC/LH/LD
036-074
KG/KC 024-090
KH024-072| 208/230| 21Z13| 607212-09
460| 21Z14| 607212-10
575| 21Z15| 607212-11
380/420| 21Z16| 607212-12

CAUTION
As with any mechanical equipment, contact with sharp sheet metal edges can result in a personal in­ jury. Take care while handling this equipment and wear gloves and protective clothing.

WARNING
Improper installation, adjustment, alteration, ser­ vice, or maintenance can cause property damage, personal injury or loss of life. Installation and ser­ vice must be performed by a licensed professional HVAC installer or equivalent, service agency, or the gas supplier

Installation

  1.  – Disconnect electrical power to unit.

  2. – Remove or open unit end panel. See figure 1.LENNOX LGH Power Exhaust Fans

  3.  If the unit does not already contain an economizer, install using the instructions provided with the economizer. Install optional enthalpy sensor(s) if used; refer to instructions provided with sensors.

  4. Remove gravity exhaust dampers from the economizer assembly. See figure 2.

  5. Refer to instructions provided with the economizer for hood assembly with power exhaust fan.LENNOX LGH Power Exhaust Fans - fig

  6. LG/LC/LH/LD Units Remove and discard the power exhaust fan jumper harness. See figure 3. Set fan near the unit opening and connect J18/P18 and J24/P24 plugs. See figure 4 for locations of J18 and J24.

  7. KG/KC/KH Units Set fan assembly near the unit opening and connect J132/P132 plugs. See figure 5.

  8. KG/KC/KH Units – Field-Installed Economizers OnlyLocate economizer harness wires marked K1-L1 and K1-L2 (already installed and hanging near the economizer control A6). Connect the hanging K1-L1 wire to the pink kit wire marked K1-L1. Connect the hanging K1-L2 wire to the gray kit wire marked K1-L2. Wires hanging in the unit may be pink and gray, red and black, or red and blue. Route the other end of the pink and gray kit wires to the control panel. Connect a pink kit wire to K1 contactor L1 terminal. Connect a gray wire to the K1 contactor L2 terminal using the terminal adapter provided in the kit. See figure 6.
    Note – Older economizers may be equipped with longer pink and gray wires coiled in the same area. One end of the pink and gray wires is already connected. Connect the other end according to the previous step. Discard kit wires.

  9. Install fan assembly and secure with screws provided.

  10. Install gravity exhaust in exhaust air hood as shown in the economizer installation instruction.

Set Prodigy M2 Unit Controller

Use the Unit Controller manual provided with each unit to enable the exhaust fan.
Use the following menu: Settings>Install>New M2>Exhaust Stages> 1 Exhaust Stage

M3 Unit Controller Setup

The M3 Unit Controller has power exhaust fan control options that include support for both single‐stage and two‐stage equipment. The power exhaust is controlled based on  the damper position. Refer to the Power Exhaust section of the 2.0 M3 Unit Controller Application Guide.
Go to SETUP / INSTALL and set Configuration ID 1, position 3 to (S = Single Stage or D = Dual Stage).
Go to SETUP / INSTALL and set Configuration ID 1, position 4 to A = Damper Position

M4 Unit Controller Setup

The M4 Unit Controller has power exhaust fan control options that include support for both single‐stage and two‐stage equipment. The power exhaust is controlled based on the damper position. Refer to the Power Exhaust section of the M4 Unit Controller Application Guide.
Go to RTU MENU > SETUP INSTALL and navigate through various setup questions until Configuration ID
1; set position 3 to (S = Single Stage or D = Dual Stage).
Go to RTU MENU > SETUP INSTALL and navigate through various setup questions until Configuration ID
1; set position 4 to (A = Damper Position).

Operation

Power exhaust fans are energized when economizer dampers reach 50% (default).LENNOX LGH Power Exhaust Fans - fig 1LENNOX LGH
Power Exhaust Fans - fig 2

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