AQUA
4
–AGU-1405-E
- 47 -
-
temperature and pressure indicators for routine maintenance and inspections of the unit. Pressure control on the water side allows
expansion vessel operation to be checked and any water leaks in the system to be detected in advance.
-
Sumps on inlet and outlet piping for measuring temperatures, and for directly viewing the operating temperatures. They can also
be viewed on the display on board the unit (if pCO).
-
Shut-off valves (gate valves) to isolate the unit from the water circuit for maintenance.
-
Air vent valves, placed on the higher parts of the water circuit, that bleed the air. The internal pipes of the machine are fitted with
manual air vent valves to bleed the unit:
this operation can only be carried out when the unit is disconnected from the power
supply
-
discharge cock and, if necessary, drain tank to empty the system for maintenance or seasonal stops
-
For process applications, it is recommended to install a decoupling heat exchanger, which avoids the fouling of the heat
exchangers
-
It is mandatory to install a metal net filter (inlet pipe), with a mesh not above 1 mm, to protect the heat exchanger from slag or
impurities inside the pipes. This is especially important during commissioning.
Water connection to evaporator
If not, the evaporator would be exposed to the risk of freezing, since the anti-freeze thermostat would not be able to perform its function.
Furthermore, in the cooling mode, countercurrent circulation would not be activated. Additionally, this position does not enable consent
of the water flow control device.
The dimensions and position of the water connections are provided in the dimensional tables and overall drawings.
The ON/OFF-type compressors work intermittently, since the cooling power required by the utility is not generally the same as that
supplied by the compressor. In systems containing little water, in which the thermal inertia is low, verify that the water content of the
delivery section (to users) satisfies the equation below:
Ns
Sh
Cc
V
×
∆Τ
×
×
∆
×
=
ρ
τ
V
= water content in user section
[m3]
Sh
= specific heat of fluid
[J/(kg/°C)]
e.g. 2090 [J/(kg/°C)] for water
ρ
= density of fluid
[kg/m3]
e.g. 1000 [kg/m3] for water
D
τ
= minimum time between 2 compressor restarts
[s] [s]
e.g. 120
DT
= admissible differential on water T
[°C]
e.g. 4 [°C]
Cc
= Cooling Capacity
[W]
Ns
= N° of capacity control steps
How to fill up the tank and/or the pumps (if required by the system)
It is extremely important that the installer follow and verify this procedure step-by-step to prevent the risk of tank implosion or pump
cavitation:
Inertial Tank
Ts °C
Inlet water T
Outlet water T
The tank is not designed to withstand
vacuum pressures
greater than 0.15 bar. For this reason, make sure that
the pressure on the pump intake side, where the expansion vessel is positioned, is always above 0.5 bar with
pump running. This helps reduce the risk of cavitation.
Warning: Never perform hydraulic connection operations with open flames near or inside the unit.
The AQUA
4
units are supplied as
standard
with a device that controls the water flow (paddle flow switch
supplied on board the machine).
Any tampering with this device will immediately invalidate the warranty.
It is mandatory to install a metal net filter on the water inlet piping.
It is extremely important that the water inlet is connected at the height of the “Water Inlet” sign.
The water circuit must guarantee a constant nominal flow rate of water (+/- 15%) to the evaporator in all
operating conditions.
