50
HYDRAULIC CONNECTIONS
General rules
A mesh filter (hole Ø
≤ 500 µm) must be installed on the unit’s water inlet and/or water tank otherwise warranty is imme
-
diately forfeited. The filter performs the function of blocking any foreign matter in the system’s piping circuit (shavings,
machining debris, etc.).
This prevents the plate exchanger water pipes from clogging then possibly freezing (and therefore bursting).
Comply with the local laws governing safety matters and best practices in order to correctly design the hydraulic circuit.
The following information gives suggestions on how to correctly install the unit.
1) Standard supply.
• The unit comes as standard with a differential pressure switch located between the entrance and exit of water exchanger to prevent
freezing problems in case of lack of water flow.
The intervention is calibrated to a
∆
P of 80 ± 5 mbar, while the reset occurs with a
∆
P of 105 ± 5 mbar.
The differential pressure switch contact opens and stop the unit when you reduce the water flow and so
∆
P ≤ 80 mbar ± 5.
The differential pressure switch closes and then the unit can restart when the water flow increases and so
∆
p ≥ 105 mbar ± 5.
• The unit comes standard with an antifreeze heater placed between the evaporator and its insulation controlled by the electronic
controller unit.
2) with pumping module accessory.
• Besides the standard accessories, the unit is equipped with all the hydraulic components, as specified in the “Options and acces
-
sories” section.
Hydraulic layout of the system
General suggestions
• Before connecting the unit to the system wash adequately the pipes using clean water, filling and emptying and cleaning the filters.
Only after that proceed connecting the unit to the system; this operation is crucial to ensure proper start-up without the need to make
continuous stops to clean the filter, with the possible risk of damage to heat exchangers and other components.
• Check by qualified personnel the quality of the water or of the mixture used; avoid the presence of inorganic salts, biological load
(seaweeds, etc.) suspended solids, dissolved oxygen and the pH. Water with inadequate characteristics can cause a pressure drop
increase due to a rapid fouling of the filter, energy efficiency decrease and corrosive symptom increase that can damage the unit.
• The pipes must have the least possible number of bends to minimize load losses and must be adequately supported in order to
prevent the connections of the unit from being excessively stressed.
• Install on-off valves near components that need to be serviced to isolate them when maintenance work needs to be done and to
allow them to be replaced without having to discharge the system.
• Before isolating the pipes and charging the system, carry out preliminary inspections to make sure that there are no leaks.
• Isolate all the chilled water pipes to prevent condensation from forming along the pipes themselves. Make sure that the material
used is the steam barrier type, failing this, cover the insulation with an appropriate protection. Also make sure that the air venting
valves can be accessed through the insulation.
• Do not forget to install or at least allow for the installation of pressure and temperature reading instruments on the inlet and outlet
parts of the hydraulic circuit. These instruments will allow you to monitor the operation of the system.
• The circuit can be kept under pressure by means of an expansion tank (with which the unit is equipped if the pumping module
accessory is installed) and a pressure reducer. A plant filling unit can also be used in order to automatically charge the system and
keep it at the desired pressure if it drops below a certain pressure value. Install manual or automatic values in the highest point of the
system to eliminate air from the circuit.
Fit manual or automatic valves at the highest point in the circuit in order to vent air from the circuit.
• Depending on the chosen accessory, there may be male threaded connections or Victaulic-type joints for hooking up to the unit.
The joints allow the pipes to expand due to changes in temperature and in addition the elastomer gasket and the specified play help
insulate and absorb noise and vibration.
• If anti-vibration mounts are installed under the unit, it is recommended to use flexible couplings before and after the water circulation
pump and near the unit.
• Install a tap on the outlet of the unit in order to regulate the water flow.
• Avoid that the weight of the connection pipes pushes on the hydraulic connections of the unit using approved supports.
• It is advisable to insert a water paddle flow switch (optional accessory FLS) just before evaporator water inlet to be connected in
series with the differential pressure switch, supplied as standard.
Precautions for the winter
The water could freeze and damage the exchanger of the unit and other parts of the system during the winter period, if the system
was to remain at a standstill. This problem can be obviated in 3 different ways:
1.
Drain the system completely, taking care to drain the plate exchanger (in order to drain the unit’s piping system completely, open
the water drain ball valves and the air vent valves, open any valves closed).
2.
Operate with glycol water taking account, depending on the % of glycol, of the factor of correction of the refrigerating capacity,
power input, water flow rate and losses of head (see table on following page)
3.
If it is certain that the unit will always be powered throughout the winter, the unit is able to protect itself from freezing, down to a
temperature of -20°C: this is possible thanks to an antifreeze electric heating element installed on the plate exchanger and intelligent
control of the water pump that must be governed by the microprocessor board (see the “Electric Connections” section). If the unit is
fitted with a Storage tank, solution no. 3 requires installing the tank antifreeze heating element accessor
(RAG).
It is recommended to protect the pipes placed outside with heating cables placed below the insulation.
Summary of Contents for RHA series
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