Airflow Balancing - Fxa/Fxk - Lennox FLEXY FC 050 Series Installation - Operating & Maintenance Manuel

AIRFLOW BALANCING - FXA/FXK

AIRFLOW BALANCING - FXA/FXK AIRFLOW BALANCING - FXA/FXK AIRFLOW BALANCING - FXA/FXK AIRFLOW BALANCING - FXA/FXK
The FX* models are designed to operate with more
complex supply and extract ductwork systems. Without
balancing there are numerous risks:
- Fan motor overvoltage
- Significant flow variations depending on the
position of the dampers, which affects the building
concerned, especially when applied to pressure
balanced systems.
To rectify this we have fitted an equilizing grill on the
fresh air dampers. The grill can be moved after
unscrewing the knurled nuts (1 - Figure 14) and
operates as an adjustable damper.
Before starting to adjust fully open the equilising grills.
To equilise, proceed as follows:
A. Set the unit to the "recycle air" position (Figure
15)
B. Measure the static pressure in the areas
indicated 1/2/3/4/5/6
C. Before proceeding further, check that the pres-
sure difference between zones 1 and 4 satisfies
the static pressure required.
If this is not the case, refer to the "AIR FLOW
BALANCING" section.
Example :
Zone
Technical specification
Recycled air without setting
Recycled air after setting b/b'
Fresh air before setting
Fresh air after setting grill a
Fresh air after setting grill b'
Soufflage
1
Page 20 - IOM / ROOF-TOP FLEXY™ Series
Air extrait
2 3 4 5
a
b, b'
Air neuf
Figure 15
FX in "recycle air" position
D. If the flow and the pressure are correct:
On grills "b" and "b'", bring the pressure at 5 to
the same level as 3 (the grills must be moved
simultaneously by the same amount).
E. Check that the power absorbed by the extract
fan motor is less than its rated power.
If the values are not the same, refer to the "AIR
FLOW BALANCING" section.
F. Switch the unit to "fresh air" (Figure 16), and
measure the static pressure at 2/3/4/5/6.
G. Adjust grill "a" so that the value measured at 3 is
the same as the value at point B.
H. Finally check that the pressure at 5 is the same
as the pressure measured at point B. If not,
slightly adjust
the grill "b"
setting of the
fresh air by-
pass.
1 2
200
190 -230 -210
190 -230 -210
270 -80 -50
190 -230 -210
190 -230 -210
6
Rejet
1
3 4 5
-180
-190 -70
-190 -210
-200 -220
-200 -220
-190 -210
FX in "fresh air" position
Grill b'
fresh air by pass
Figure 14
6
-120
-240
-250
-250
-240
Figure 16