Installation, user and maintenance manual
– GAHP-A
35
Activate the automatic air purging valves of the plant and open all thermostatic
1.
valves.
Fill the hydraulic circuit with clean water and add, if necessary, the proper quantity
2.
of monoethylene glycol according the minimum winter temperature in the instal-
lation site (see table 5.3 Technical data for filling the hydraulic circuit
→
36).
Check the filter on the return pipe for impurities; clean it if necessary.
3.
Bring the plant to the correct pressure, making sure that the water pressure is not
4.
less than 1 bar and not over 2 bar, and run the circu lation pump for at least 30 min-
utes. Check the water filter 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 inter-
mediate state of oxidation which, in the presence of oxidising agents such as oxygen,
are transformed into corresponding acids. This transformation into acids increases the
corrosive nature of the fluid contained in the circuit. For this reason, mixtures that are
commercially available almost always contain inhibiting substances that are able to con-
trol the pH of the solution. A condition necessary for the oxidation and degradation of
glycol 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 time, once the oxygen ini-
tially 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
damages caused by the use or disposal of glycol antifreeze�
It is equally important to recall that the use of monoethylene glycol modifies the ther-
mophysical characteristics of the water in the plant, and in particular its density, viscosity
and average specific heat. Always check the date of expiry and/or degradation of the
product with the supplier.
In the Table 5.3 Technical data for filling the hydraulic circuit
→
36 the approximate freez-
ing temperature of the water-glycol mixture and the consequent increase in pressure
drops of the appliance are shown, according to the percentage of monoethylene glycol.
This Table 5.3 Technical data for filling the hydraulic circuit
→
36 should be taken into
account for the sizing of the pipes and the circulation pump (for calculation of internal
pressure drops of the appliance, refer to the Table 3.1 GAHP-A LT technical data
→
11 or
Table 3.2 GAHP-A HT technical data
→
13).
Nevertheless, it is advisable to consult the technical specifications of the monoethylene
glycol used. If automatic loading systems are used, a seasonal check of the quantity of
glycol present in the plant is also necessary.
