Trane CXAU - Page 19

Installation- Mechanical
19PKGP-SVX19A-EN
6). The ow speed of the water of the unit should not be too large, otherwise the friction resistance is too large. The general
friction resistance range is 100~300Pa/m, and the optimal range is 150~200Pa/m. Piping size is recommended according
to the following speed.
Diameter
25 32 40 50 70 80 100 125 150 200 250 300 350 >400
Speed (m/s)
<0.5 0.5-0.6 0.5-0.7 0.5-0.9 0.6-1 0.7-1.2 0.8-1.4 0.9-1.6 1.0-1.8 1.2-2.1 1.4-2.3 1.6-2.4 1.8-2.6 1.9-2.8
7). The water capacity of the unit should meet the minimum water capacity, refer to the following table. Minimum capacity
of the water storage tank = minimum water capacity of the unit - water pipeline capacity - water capacity of the airside
terminals. When only single unit is running, the minimum e󰀨ective water capacity should be multiplied by the coe󰀩cient:
rated water ow / actual water ow.
Unit
Entering Temp.
Setting (
o
C)
Minimum Water
Volume (L)
Unit
Entering Temp.
Setting (
o
C)
Minimum Water
Volume (L)
CXAU130
15 480
CXAU065
15 680
14 545 14 820
13 630 13 1020
12 740 12 1360
11 740* 11 1360*
10 740* 10 1360*
* When the setting value of entering water temperature is lower than the default value, the antifreeze protection temperature
needs to be decreased accordingly.
`
!
CAUTION
●
The automatic exhaust valve should be installed at the highest point of the pipeline, and the water pipe diameter
at the installation point should be expanded.
●
The drain valve should be installed at the lowest point of the pipeline to facilitate the drainage.
●
The reversed return water system design facilitate uniform distribution of water ow.
●
The FCU near the inlet and outlet of the unit should be equipped with a two-way valve to avoid short circuit.
●
The appropriate working water capacity can ensure the normal defrosting in winter and the minimum operating
time of the unit.
●
The system must be equipped with an automatic water make-up valve. The system should be equipped with an
automatic exhaust valve at the highest point of the pipeline.
●
A three-way valve should be installed at every far end FCU (except the largest FCU) to avoid low water ow
alarm.
`
!
WARNING
All external water piping systems should be thoroughly ushed before the main unit is connected to the external
water piping system. Any impurities are strictly forbidden in the water piping system. Otherwise, any failure or
damage of the unit will cause the customer paid services in accordance with the company’s relevant policies.
28.
Variable Water Flow Control
If variable water pump is equipped, the water system needs to control the variable water ow rate. It is necessary to install the
water solenoid valve only for the slave units and connect it to the SV2 point in OUT6 of the unit control board (active).No water
2-way valve is needed for the host unit. A di󰀨erential pressure bypass valve should be installed in the main water pipeline to
ensure that the water ow through the running unit meet requirements.
The frequency could be controlled according to the number of units, water pressure drop, etc. And the switch of the variable
water pump needs to be connected to the MP point in OUT1 of the host unit control board (passive).