Lennox LCH036 Installation Instructions Manual page 111

C-Determining Unit CFM
VFD Units - Refer to the Optional Supply Air VFD
section to initiate a blower only (G) demand.
1- The following measurements must be made with a
dry indoor coil. Run blower without a cooling demand.
Measure the indoor blower shaft RPM. Air filters must
be in place when measurements are taken.
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.
Note - Static pressure readings can vary if not taken
where shown.
3- Referring to Page 13, use static pressure and RPM
readings to determine unit CFM. Use Page 14 when
installing units with any of the optional accessories listed.
4- 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 14. Do not exceed
minimum and maximum number of pulley turns as
shown in table 3.
TABLE 3
MINIMUM AND MAXIMUM PULLEY ADJUSTMENT
Belt
Minimum Turns Open
A Section No minimum
B Section
*No minimum number of turns open when B belt is used on
pulleys 6" O.D. or larger.
INSTALLATIONS WITH DUCTWORK
ROOFTOP UNIT
SUPPLY
MAIN
DUCT RUN
Maximum Turns Open
5
1* 6
LOCATION OF STATIC PRESSURE READINGS
RETURN AIR
READING LOCATION
RE­
TURN
FIRST BRANCH
OFF OF MAIN RUN
SUPPLY AIR
READING
LOCATION
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. See figure 16 for
blowers not equipped with a tensioner and figure 17 for
blowers equipped with an optional tensioner.
Blowers Without Belt Tensioner
1- Loosen four screws securing blower motor to sliding
base. See figure 14.
2- To increase belt tension -
Turn belt tension adjusting screw to the right, or
clockwise, to tighten the belt. This increases the
distance between the blower motor and the blower
housing.
To loosen belt tension -
Turn the
counterclockwise to loosen belt tension.
3- Tighten four screws securing blower motor to sliding
base once adjustments have been made.
Blowers Equipped With Belt Tensioner
1- Loosen the bolt in the center of the tensioner. See
figure 18.
2- Place belt over all three pulleys. Tensioner pulley
must be oriented toward blower, not motor.
3- Using a 15/16" wrench on the tensioner body nut, turn
the tensioner nut until marks align (3rd mark).
4- Hold the tensioner with marks aligned and tighten the
bolt to 22 ft.lbs. using the 9/16" wrench.
5- If tensioner pulley is past 7 o'clock when secured,
The distance between the motor and blower pulleys
need to be increased. Refer to the steps in figure 14
to increase belt tension.
INSTALLATIONS WITH CEILING DIFFUSERS
SUPPLY AIR
READING
LOCATION
FIGURE 15
Page 11
adjusting screw to
ROOFTOP UNIT
RE­
SUPPLY
TURN
DIFFUSER
the left, or
RETURN AIR
READING
LOCATION