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___________________________________RAH / PAH Ka_________________________________
3.5.4 HYDRAULIC CIRCUIT FILLING
Once the hydraulic circuit is done, the unit connected and the system seal test performed, ll the circuit, following the here below described steps.
a) Open all the vent valves on the circuit;
b) Connect the circuit, if possible permanently, to the water supply system, using an automatic lling group provided with a manometer and a check valve.
c) If the circuit works with an antifreeze mixture, ll the circuit with an appropriate quantity of antifreeze uid, according to the system size and the antifreeze
concentration to reach.
d) Start to ll the system with water using the lling group;
e) Check all the vent valves on the system, and close them when water, instead of air, starts to come out;
f) Once all the vent valves are closed, go on lling the system with water until a pressure between 1,5 and 6 bar is reached.
g) Stop the water charge, and switch on the circulation pumps making them working for at least 2 hours, so that any presence of air can be gathered to the
top points where the air vent valves are installed.
h) Stop the pump and discharge the gathered air, if present, by opening one after the other the air vent valves installed in the system;
i) Charge circuit with water to bring pressure back to its original value.
j) Repeat the steps from g) to i) until no air comes out from the air vent valves.
3.5.5 ANTIFREEZE MIXTURE USE
If , during the unit operation, the cooled uid temperature is expected to fall below 4 degrees or, during stops, can get near to 0°C, introduce inside the circuit an
antifreeze mixture, having a freezing point enough lower than the foreseen minimum temperature.
Some antifreeze liquids are dangerous if ingested or can cause skin and sensitive mucous membranes irritation. Carefully follow the safety instructions
on their bottle or instructions for use.
It is in any case recommended to wear protection glasses and rubber gloves. Also avoid the contact with the mouth.
It is forbidden the use of aggressive antifreeze mixture or those ones not compatible with copper, carbon steel, aluminium and all the other material
present in the system.
As an example, here below the freezing points for different values of ethylene glycol concentration in water are listed.
The values in the table are just an indication and must be used just as a reference. Sometimes the suppliers deliver the product already thinned, therefore you
have to refer to the dilution rate indicated by the uid manufacturer.
EHTYLENEGLYCOLPERCENTAGEONTHEMIXTURE(INMASS[KG/KG]
5% 20% 25% 30% 35% 40%
4,4% 27,7 37,5
The use of mixtures with glycol percentage lower than required one, could cause freezing and breaking of the hydraulic circuit and especially of the evaporator. The
use of useless high percentages, could cause a reduction of the unit performances and particularly of its energy efciency.
The uid in the hydraulic circuit must be periodically analyzed and anyway at the beginning of the cool season, in order to verify its composition and concentration.
The uid in the system must be replaced with the frequency indicated by the antifreeze substance Manufacturer and anyway every 2 years.
Absolutely do not release the antifreeze solution in the environment, but deliver it to authorized waste disposal services, in compliance with current local
laws and Norms.
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