Two-Speed Blower Operation; Minimum And Maximum Pulley Adjustment; Field-Adjustable Blower Speeds - Direct Drive - 460/575V - Lennox KGB024 Installation Instructions Manual

FIELD-ADJUSTABLE BLOWER SPEEDS - DIRECT DRIVE - 460/575V

TAPE BACK AND SECURE
UNUSED ISOLATION LEAD
TO CAPACITOR WIRES.
MEDIUM SPEED 036, 048 UNITS
L1-Terminal COM
L2-Terminal MED
Park isolation
lead into
terminal HI
C-Determining Unit CFM - Belt Drive Blowers
IMPORTANT - KGB/KCB074 blower (G thermostat)
CFM MUST BE ADJUSTED IN HIGH SPEED.
Disconnect factory-installed
connector from P350. Connectors are located near the
bottom of the control box. Connect J351 high speed
connector to P350. Once blower CFM is set, J350 can
be reconnected to operate the blower on low during
ventilation only demands. See table 3.
TABLE 3

TWO-SPEED BLOWER OPERATION

KGB/KCB074 UNITS
Thermostat
G (P350/J350)*
G (P350/J351)
W1
W2
Y1
Y2
*Factory-installed jack/plug connection.
1- The following measurements must be made with air
filters in place.
2- With all access panels in place, measure static
pressure external to unit (from supply to return).
Blower performance data is based on static pressure
readings taken in locations shown in figure 15.
KG/KC 024, 030, 036, 048, 060, 072, 074, 090
Do not park
isolation lead
1-COM
2-HI
3-MED
4-LOW
J350 low speed
Blower Speed
Low
High
High
High
Low
High
HIGH SPEED
L1-Terminal COM
L2-Terminal HI
1-COM
2-HI
3-MED
4-LOW
Park isolation
lead into
terminal HI
FIGURE 18
Note - Static pressure readings can vary if not taken
where shown.
3- Measure the indoor blower wheel RPM.
4- Referring to belt drive blower tables, use static
pressure and RPM readings to determine unit CFM.
Use the air resistance tables when installing units
with any of the options or accessories listed.
5- The blower RPM can be adjusted at the motor pulley.
Loosen Allen screw and turn adjustable pulley
clockwise to increase CFM. Turn counterclockwise to
decrease CFM. See figure 19. Do not exceed
minimum and maximum number of pulley turns as
shown in table 4.
6- KGB/KCB074 Unit Only -
If low speed during ventilation is desired, replace
J351 connector with J350.

MINIMUM AND MAXIMUM PULLEY ADJUSTMENT

Belt
A Section
D-Blower Belt Adjustment
Maximum life and wear can be obtained from belts only
if proper pulley alignment and belt tension are
maintained. Tension new belts after a 24-48 hour
period of operation. This will allow belt to stretch and
seat grooves. Make sure blower and motor pulley are
aligned as shown in figure 20.
Page 12
LOW SPEED 036, 048 UNITS
L1-Terminal COM
L2-Terminal LOW
Park isolation
lead into
terminal HI
1-COM
2-HI
3-MED
4-LOW
LOW SPEED 060 UNITS
L1-Terminal COM
L2-Terminal LOW
1-COM
2-HI
3-LOW
4
TABLE 4
Min. Turns Open Maxi. Turns Open
No minimum 5