Technical data
34
4.6 FILLING OF HYDRAULIC CIRCUIT
After having completed all the connections of the hydraulic, electrical and gas supply
plants, the hydraulic system installation technician can proceed with lling the hydraulic
circuit, observing the following stages:
You will need: the appliance connected hydraulically and electrically.
Activate the automatic air bleeding valves present in the plant and open all ther-1.
mostatic valves.
Fill the hydraulic circuit, ensuring the minimum water content in the plant, and 2.
adding, if necessary, to the plant water (free of impurities) a quantity of monoethyl-
ene glycol in proportion with the minimum winter temperature in the installation
zone (see table 4.2 Percentage of monoethylene glycol → 35).
Check the lter on the return pipe for impurities; clean it if necessary.3.
Check that the siphon on the drainage condenses has been lled with water as 4.
indicated in the relative paragraph.
Bring the plant to the correct pressure, making sure that the water pressure is not 5.
less than 1 bar and not over 2 bar, and run the circu lation pump for at least 30 min-
utes. Check the water lter again and clean it if necessary.
To facilitate the operation of bleeding air from the hydraulic circuit, the appliance is
equipped with an additional manual air bleeding valve.
Possible use of glycol antifreeze
Glycols, normally used to lower the freezing point of water, are substances in an interme-
diate state of oxidisation which, in the presence of oxidising agents such as oxygen, are
transformed into corresponding acids. This transformation into acids increases the corro-
sive nature of the uid contained in the circuit. For this reason, mixtures that are commer-
cially available almost always contain inhibiting substances that are able to control the
pH of the solution. A necessary condition for the oxidisation of the glycol, and therefore
its degradation, is the presence of an oxidising agent such as oxygen. In closed circuits
in which no replenishment of water, and therefore of oxygen, occurs over the course of
time, once the oxygen initially present has reacted, the degenerative phenomenon of
glycol is hugely inhibited.
Most circuits, however, are of the non-sealed type, and therefore receive a more or less
continuous supply of oxygen.
Therefore it is essential, whatever type of glycol is in question, to verify that it is ade-
quately inhibited and that the necessary checks are regularly performed during its entire
period of use.
Antifreeze liquids for cars, which do not contain inhibiting components other than ethyl-
ene glycol, are not recommended for cooling and heating plants.
The manufacturer does not accept any contractual or extra-contractual liability for
damage caused by the use or incorrect disposal of glycol antifreeze.
It is equally important to recall that the use of monoethylene glycol modies the ther-
mophysical characteristics of the water in the plant, and in particular its density, viscosity
and specic average heat. Always check the date of expiry and/or degradation of the
product with the supplier.
In the Table 4.2 Percentage of monoethylene glycol → 35 is shown the approximate
freezing temperature of the water and the consequent increased drop in pressure of the
appliance and of the circuit of the plant, according to the percentage of monoethylene
glycol.