Page 8
D-Determining Unit CFM
1- The following measurements must be made with a
dry indoor coil and air filters in place.
Units
Not
Equipped With An Inverter -
Run blower without a cooling demand.
Units Equipped With An Inverter -
Initiate high speed blower without a cooling demand.
Disconnect high pressure switches S4 and S7. Run
the blower with Y1
and
Y2 demands.
2- Measure the indoor blower shaft RPM.
3- 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 7.
Note - Static pressure readings can vary if not taken
where shown.
4- Referring to page 10 or 11, use static pressure and
RPM readings to determine unit CFM. Use page 12
when installing units with any of the optional
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 6. Do not exceed minimum
and maximum number of pulley turns as shown in
table 1.
6-
Units Equipped With An Inverter -
Reconnect high pressure switches S4 and S7.
TABLE 1
MINIMUM AND MAXIMUM PULLEY ADJUSTMENT
Belt
Minimum
Turns Open
Maximum
Turns Open
A Section
0
5
B Section
1*
6
*No minimum number of turns open when B belt is used on
pulleys 6” O.D. or larger.
E-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 in the pulley grooves. Make sure blower and motor
pulleys are aligned as shown in figure 8.
1- Loosen four bolts securing motor base to mounting
frame. See figure 6.
2-
To increase belt tension -
Turn both adjusting bolts to the right, or clockwise, to
move the motor outward and tighten the belt. This
increases the distance between the blower motor and
the blower housing.
To loosen belt tension -
Turn the adjusting bolts to the left, or
counterclockwise to loosen belt tension.
IMPORTANT - Align top edges of blower motor base and
mounting frame base parallel before tightening two bolts
on the other side of base. Motor shaft and blower shaft
must be parallel.
3- Tighten two bolts on each side of the motor mounting
base. This secures the mounting base to the frame.
FIGURE 7
LOCATION OF STATIC PRESSURE READINGS
SUPPLY AIR
READING
LOCATION
SUPPLY
RE
TURN
INSTALLATIONS WITH DUCTWORK
SUPPLY
RE
TURN
INSTALLATIONS WITH CEILING DIFFUSERS
MAIN
DUCT RUN
FIRST BRANCH
OFF OF MAIN RUN
DIFFUSER
ROOFTOP UNIT
ROOFTOP UNIT
SUPPLY AIR
READING
LOCATION
RETURN AIR
READING LOCATION
RETURN AIR
READING
LOCATION
