C6.1.10/0118-0318/E
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3.6 Air ducts connection
WARNING
Uncovered rotating parts! No safety grids on the condenser fans!
Personal injuries!
Never start the condensing unit or run the fans with no air
ducts connected or without protective end-grids on the air outlets.
The connection of the air ducts to the condensing unit has to be made based on standard rules
for air distribution ducts. Duct connection dimensions are designed based on standard EN 1506-
2007, which has to be taken into consideration for all air ducts dimensioning.
The foil must be removed from the condenser fan before connecting the air ducts.
The condensing units covered in these guidelines are prepared for connection to air ducts with a
diameter of 500 mm.
Before commissioning and starting the unit, check the ducts for air leaks. Look for sections that
should be joined but might be separated and for possible holes in the air channels.
Two values must be taken into consideration when designing a proper air duct route and selecting
component parts, ie, the total pressure drop and the airflow.
The length of the air duct has little impact on the total pressure drop and on the air-flow (pressure
drop ~ approx. 0.5-1 Pa/m). An air duct length of up to 5 meters has virtually no impact at all on
pressure drop.
Elbows and other components such as diameter reductions on the air duct route have a much
bigger influence on total pressure drop and air flow
– see
Table 23
below.
Air duct diameter Ø 500 mm (connection to condenser per fan)
Total straight length (m)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Nu
mb
er
of
elbo
w
s
1
2
3
4
5
6
Table 23: Maximum acceptable air duct length depending on diameter and number of elbows
When taking into account all the fittings, the total linear length and additional components, the total
pressure drop should be limited to 60 Pa per fan at 3500 m³/h. Please also refer to Chapter 2.10.3
"Main control & safety features".
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