Lennox Baltic BCK 020 Installation, Operating And Maintenance page 55

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
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.
Table - 3 - Accessories pressure drops
Economiser
SIZE Airflow (Pa)
2900 18
020
3600 28
4300 39
3600 28
025
4500 43
5400 62
4300 17
030
5400 26
6500 38
5000 22
035
6300 36
7600 52
5800 18
040
7200 28
8600 40
6500 23
045
8100 36
9700 51
7200 28
050
9000 44
10800 63
8600 16
060
10800 25
13000 37
9 950 22
070
12600 35
14000 56
Page 54 - IOM / ROOFTOP BALTIC Series - 0704 - E
Transmission
x η
Transmission
x η
meca motor Transmission
EU4 F7
Filters Filters
(Pa) (Pa)
0 39
6 66
12 98
6 66
14 108
25 160
1 43
8 74
15 111
5 62
14 104
24 155
0 39
6 66
12 98
3 52
10 86
18 127
6 66
14 108
25 160
3 50
9 84
18 125
7 70
16 117
31 194
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
INT
using the results from above, the external static pressure
(ESP) can then be estimated:
ESP = P
Table 2
MotorSize
0.75 kW
1.1kW
1.5kW
2.2kW
3.0kW
4kW
5.5kW
7.5kW
Hot Electric
Water Coil heater (Pa)
(Pa) S M H
31 37 38 40
46 55 57 59
61 76 79 81
46 55 57 59
66 83 85 88
89 117 120 123
40 42 45 47
59 63 66 69
80 89 93 96
51 55 58 61
76 84 88 91
105 119 123 127
46 50 53 57
67 74 78 82
91 101 106 111
56 61 65 69
82 91 95 100
113 126 131 137
67 74 78 82
99 110 115 120
136 154 160 166
58 42 47 52
86 61 67 73
119 82 89 97
75 54 59 65
113 78 85 92
172 116 125 134
) and the corresponding
TOT
+ ∆ ∆ ∆ ∆ ∆ P
+ coil + P
filter Inlet Options
- Pd - ∆ ∆ ∆ ∆ ∆ P
TOT INT
ϕ
Nom. Speed Cos
1400 rpm 0.77
1429 rpm 0.84
1428 rpm 0.82
1436 rpm 0.81
1437 rpm 0.81
1438 rpm 0.83
1447 rpm 0.83
1451 rpm 0.82
Multi-
roofcurb directional module
(Pa) (Pa) fresh air
16 23
24 35
35 50
24 35
38 55
55 79
19 18
29 28
42 41
25 24
39 38
58 56
16 23
25 35
36 51
20 29
32 45
46 64
25 35
39 55
56 80
19 12
29 18
43 26
25 16
40 25
65 40
(1) to be added to extraction fan ESP
η
meca motor
0.70
0.77
0.79
0.81
0.83
0.84
0.86
0.87
Heat Recovery
module
(1)
108 69
161 105
226 151
161 105
247 165
352 238
113 68
172 123
244 178
149 105
230 167
331 243
92 63
136 98
190 139
113 80
170 124
239 177
136 98
207 153
293 220
129 91
198 143
282 207
171 123
266 195
326 240