Installation, user and maintenance manual
– GAHP-A
33
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 there is 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 adequately
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
ethylene 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 modifi es the
thermophysical characteristics of the water in the plant, and in particular its density,
viscosity and specifi c 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 on page 33 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.
This Table 4.2 Percentage of monoethylene glycol on page 33 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 2.1 GAHP-A HT technical data on page 11).
Nevertheless, it is advisable to consult the technical specifi cations 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.
Table 4.2
– Percentage of monoethylene glycol
% of MONOETHYLENE GLYCOL
10
15
20
25
30
35
40
WATER FREEZING POINT TEMPERATURE
-3°C
-5°C
-8°C
-12°C
-15°C
-20°C
-25°C
PERCENTAGE OF INCREASE IN PRESSURE DROPS
--
6%
8%
10%
12%
14%
16%
LOSS OF EFFICIENCY OF UNIT
--
0,5%
1%
2%
2,5%
3%
4%
Technical data for fi lling the hydraulic circuit
If the percentage of glycol is ≥ 30% (for ethylene glycol) or ≥ 20% (for propylene glycol):
• then parameter 182 in menu 4 must be set to “1” (at the installer’s care).
4.7
FLUE INFORMATION
The appliance is approved for the connection of the combustion product fl ue pi pes,
present on each single unit, to a fl ue linked directly to the outside.
Each single unit is provided with a connection of Ø 80 mm (equipped with a suitable seal)
located on the left side (see Figure 2.1 Size (Standard ventilation) on page 12 or Figure 2.2
Size on page 13) and outlet in a vertical position.
Each unit of the appliance is supplied complete with an exhaust air duct installation kit,
to be fi tted to the appliance by the hydraulic system installation technician.
