Filters - Lennox BCK 020 Installation Operating & Maintenance Manual

VENTILaTION : AIRFLOW BALANCING
2nd method when adjusting the pulley :
-Close the pulley fully and count the number of turns from
fully closed position. Using table 1 determine the motor
pulley actual diameter.
-Record the fix fan pulley diameter.(DF)
-Determine the fan speed using the following formula:
rpm FAN = rpm MOTOR x D M / D F
Where : rpm MOTOR :from the motor plate or table 2
D M : from table 1
D F : from machine
Once the pulleys are adjusted and the belt checked and
tensioned, start the fan motor and record the Amps and
Voltage between the phases :
Using the measured data and table 2
-Theoretical mechanical power at the fan shaft :
x η
P = P
meca fan meca Motor Transmission
x η x η
P = P
meca fan elec meca motor
= V x I x √3 x cosϕ x η
P
meca fan
This formula can be approximated in this way
P = V x I x 1.73 x 0.85 x 0.76 x 0.9
meca fan
With the fan "rpm" and the mechanical power at the fan
shaft an operating point and the supplied airflow can be
estimated using the fan curves.
Accessories pressure drop
Table 3
-
Economiser
SIZE Airflow (Pa)
2900 8
020
3600 13
4300 18
3600 13
025
4500 20
5400 28
4300 11
030
5400 17
6500 24
5000 14
035
6300 23
7600 33
5800 18
040
7200 28
8600 40
6500 23
045
8100 36
9700 51
7200 28
050
9000 44
10 800 63
Transmission
x η
meca motor Transmission
EU4 Hot

Filters

water coil (Pa)
(Pa) S
0 22
6 32
12 43
6 32
14 46
25 63
1 29
8 43
15 59
5 37
14 56
24 77 105
0 35
6 51
12 70
3 43
10 63
18 87 113
6 51
14 76
25 105 136
CHECKING AIRFLOW AND ESP
Using the fan curves on page 25, 26, 27, the airflow, the
total pressure available (P
dynamic pressure (Pd) can now be estimated, for a specific
operating point;
The next step consist in estimating the pressure losses
across the unit.
This can be achieved using the "dirty filter pressure sensor"
and the accessories pressure drop table:
Also the pressure drop due to the duct inlet into the roof-top
unit can be taken as 20 to 30 Pa.
∆P = ∆P
+ coil + P
filter
INT
using the results from above, the external static pressure
(ESP) can then be estimated:
- Pd - ∆P
ESP = P
TOT
Table 2
Motor Size Nom, Speed
0,75 kW 1400 rpm
1,1kW 1425 rpm
1,5kW 1430 rpm
2,2kW 1430 rpm
3,0kW 1425 rpm
4kW 1425 rpm
5,5kW 1430 rpm
Electric
heater (Pa)
H S M
31 37 38
46 55 57
61 76 79
46 55 57
66 83 85
89 117 120
40 42 45
59 63 66
80 89 93
51 55 58
76 84 88
119 123
46 50 53
67 74 78
91 101 106
56 61 65
82 91 95
126 131
67 74 78
99 110 115
154 160
IOM / ROOFTOP BALTIC Series - 0803 - E Page 35
) and the corresponding
TOT
+ ∆P
Inlet Options
INT
Cos meca motor
0,77 0,70
0,82 0,77
0,81 0,75
0,81 0,76
0,78 0,77
0,79 0,80
0,82 0,82
Multi-
roofcurb directional
H (Pa) (Pa)
40 16 23
59 24 35
81 35 50
59 24 35
88 38 55
123 55 79
47 19 18
69 29 28
96 42 41
61 25 24
91 39 38
127 58 56
57 16 23
82 25 35
111 36 51
69 20 29
100 32 45
137 46 64
82 25 35
120 39 55
166 56 80