Lennox ROOFTOP FLEXY FXK 100, Инструкция по установке, эксплуатации и обслуживанию, Страница: 37 / 110

IOM – FLEXY II – 1007 – E Page 35
The actual resistance of ductwork systems is not alway s identical to the calculated theoretical v alues. To rectify this, it may be
necessary to modify the pulley and belt setting. To this effect, the motors are fitted with v ariable pulleys.
SITE TEST AND MAINTEN ANCE
Measure the motor absorbed power.
If the absorbed power is greater and the pressure lower than the rated v alues, the v entilation system has a lower pressure
drop than anticipated. Reduce the flow by reducing the rpm. If the system resistance is signif icantly lower than design, there is
a risk that the motor will ov erheat resulting in an emergency cut out.
If the absorbed power is lower and the pressure greater than the rated v alues, your system has a higher pressure drop than
anticipated. Increase the flow by increasing the rpm. At the same time you will increase the absorbed power which may result
in hav ing to increase the motor size.
To carry out the adjustment and to avoid a time-consuming re-start, stop the machine and if necessary lock the main switch.
First unscrew the 4 Allen screw(s) on the pulley (see f igure 13).
Actual diameter (DM) or distance between faces for a giv en number of
turns from f ully closed with SPA belt in (mm)
Pulley
ty pe
Pulley
External
Diameter
Min
Dia /
Min
Dist
Max
Dia /
Max
Dist
Nb of turns
from fully
closed to
f ully open
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
95 116 5 114 112 110 108 106 103 101.3 99.2 97.1 95 -
8450 /
D8450
120
20.2 28 5 21 21.8 22.5 23.3 24.1 24.9 25.7 26.4 27.2 28 -
110 131 5 129 127 125 123 121 118 116 114 112 110 -
8550 /
D8550
136
20.6 31.2 5 21.6 22.7 23.8 24.8 25.9 26.9 28 29.1 30.1 31 -
Table_1
The easiest way to determine the f an rotation speed is to
use a Tachometer. If not available the f an rpm can be
estimated using the following two methods.
1
st
Method with the pulley secured in place:
Measure the distance between the two outside f aces of the
pulley.
Using table (1) the motor pulley actual diameter can be
estimated.
VENTILATION : AIRFLOW BALANCING
L
Fig. 13