11
Number of
elements
p (Pa)
p (Pa)
Rectangular elbow horizontal 90°
4
5
20
Flexible tube (DN125)
13.5 m
1.85 (at 150 m
3
/h)
25
Air intake grid
1
25
25
Total:
70
Table 2: Example of pressure drop calculation
Note:
As mentioned above, the total loss of static pressure, which can be calculated by adding
up the losses of individual elements built into the pipeline system, may not exceed 95 Pa. If
they do, the values of COP start dropping more dramatically.
DETERMINING THE FAN SETTING
When pressure drop is determined, select the mode in which the fan will operate. This
determines the speed of the fan. The mode is selected using Diagram no. 1, which shows
the aerodynamic characteristics of the fan depending on the air flow and pressure drop in
the pipeline*.
Note:
*Pressure drop in the pipeline
– in diagram 1 this is marked as pressure difference.
Zone of operation of the sanitary heat pump
On diagram 1 there are two zones of operation of the sanitary heat pump among the
curves:
• The dark zone represents the area of use with higher efficiency. The volumetric air flow is
higher in this zone, which requires a lower pressure drop (channel system version with
minimum pressure drop).
• The light zone represents the area of use with lower air flow in relation to the pressure
drop and fan setting.
Noise
Like the aerodynamic characteristics rise from the lowest to the highest, the noise
increases as well. Between the aerodynamic characteristics 80% and 100 % there is a
zone with increased noise.
Checking the calculation of pressure drop
Determining the aerodynamic characteristics based on the calculation of pressure drop
while taking into account individual elements of the pipeline and air flow is an iteration.
Once the aerodynamic characteristic has been determined and set, we must measure the
air flow in the pipeline. If the air flow does not correspond to the ventilation system, we
select the next higher or lower aerodynamic characteristic that corresponds to the
ventilation system.
