20
Table 2. Pipe diameter and unit length resistance loss of water system
Note:
The parameters in the above table will change with the update of the design manual. For details, please
refer to the HVAC System Design Manual.
Assume that two CA0065EANR module units are installed in a water system, and the return water temperature is
set to 12 degrees. The main pipe diameter is DN65. The total length of the inlet and outlet pipes is 80m. Eight of
the end wind disks remain normally open. The internal volume is 2L.
Calculation: inlet and outlet water volume = 3.14*{(65/2)/1000}2*80*103=265L
End wind disk water capacity = 10 * 2 = 20L
According to the above table can be found. Minimum capacity required by the water system Vmin.=310L
In order to avoid frequent shutdown and alarm of the unit, the capacity of the water tank must be greater than or
equal to Vmin.=310-265-20=25L
■
Water system volume calculation example
Steel pipe diameter
(mm)
Closed water system
Open water system
flow (m3/h)
kPa/100m
flow (m3/h)
kPa/100m
15
0~0.5
0~60
--
--
20
0.5~1.0
10~60
--
--
25
1~2
10~60
0~1.3
0~43
32
2~4
10~60
1.3~2.0
11~40
40
4~6
10~60
2~4
10~40
50
6~11
10~60
4~8
--
65
11~18
10~60
8~14
--
80
18~32
10~60
14~22
--
100
32~65
10~60
22~45
--
125
65~115
10~60
45~82
10~40
150
115~185
10~47
82~130
10~43
Calculation of water system holdings
Unit Type
Set the return water temperature
Minimum effective water
capacity Vmin.(I)
CA0065EANR
12
310
The effective water capacity of the water system during operation includes the total capacity of the water system,
such as the main water pipe, the water storage tank, and the normally open end of the two-way valve.
The actual effective capacity V of the water system during operation must be greater than or equal to Vmin,
otherwise the unit will frequently alarm and stop!
WARNING