Heating engineer
Installation, use and maintenance manual – GAHP A
21
3
3.5
ANTI-ICING FUNCTION
Active anti-icing self-protection
The appliance is equipped with an active antifreeze self-protec-
tion system to prevent icing. The anti-icing function (activated
by default) automatically starts the primary circulation pump
and, if required, the burner too, when the outside temperature
approaches zero.
Electrical and gas continuity
The active anti-icing self-protection is only effective if
the power and gas supplies are assured. Otherwise, an-
ti-icing liquid might be required.
3.6
ANTI-ICING LIQUID
Precautions with glycol
The manufacturer disclaims any liability for any damage
caused by improper glycol use.
Always check product suitability and its expiry date
with the glycol supplier. Periodically check the prod-
uct's preservation state.
▶
Do not use car-grade anti-icing liquid (without inhibitors),
nor zinc-coated piping and fittings (incompatible with gly-
col).
Glycol modifies the physical properties of water (den-
sity, viscosity, specific heat...). Size the piping, circula-
tion pump and thermal generators accordingly.
With automatic system water filling, a periodic check
of the glycol content is required.
With high glycol percentage (> 20…30%)
If the glycol percentage is ≥30% (for ethylene glycol) or
≥20% (for propylene glycol) the TAC must be alerted be-
fore first start-up.
When producing DHW by DHW buffer tank, use pro-
pylene glycol only.
Type of anti-icing glycol
Inhibited type glycol is recommended to prevent oxidation
phenomena.
Glycol effects
The Table 3.1
p. 21 shows, indicatively, the effects of using a
glycol depending on its %.
Table 3�1
Technical data for filling the hydraulic circuit
GLYCOL %
WATER-GLYCOL MIXTURE FREEZING
TEMPERATURE
PERCENTAGE OF INCREASE IN
PRESSURE DROPS
LOSS OF EFFICIENCY OF UNIT
10
-3°C
--
--
15
-5°C
6,0%
0,5%
20
-8°C
8,0%
1,0%
25
-12°C
10,0%
2,0%
30
-15°C
12,0%
2,5%
35
-20°C
14,0%
3,0%
40
-25°C
16,0%
4,0%
3.7
SYSTEM WATER QUALITY
Responsibility of the user/operator/installer
The installer, operator and user must assure system water quality
(Table 3.2
p. 21). Failure to comply with the manufacturer's
guidelines may affect operation, integrity and life of the appli-
ance, voiding the warranty.
System water features
Free chlorine or water hardness may damage the appliance.
Adhere to the chemical-physical parameters in Table 3.2
and the regulations on water treatment for residential and in-
dustrial heating systems.
Table 3�2
Chemical and physical parameters of water
CHEMICAL AND PHYSICAL PARAMETERS OF WATER IN HEATING/
COOLING SYSTEMS
PARAMETER
UNIT OF
MEASUREMENT
ALLOWABLE RANGE
pH
/
> 7 (1)
Chlorides
mg/l
< 125 (2)
Total hardness (CaCO
3
)
°f
< 15
°d
< 8.4
Iron
mg/kg
< 0,5 (3)
Copper
mg/kg
< 0,1 (3)
Aluminium
mg/l
< 1
Langelier’s index
/
0-0,4
HARMFUL SUBSTANCES
Free chlorine
mg/l
< 0,2 (3)
Fluorides
mg/l
< 1
Sulphides
ABSENT
(1) with aluminium or light alloys radiators, pH must also be lower than 8 (in
compliance with applicable rules).
(2) value referred to the maximum water temperature of 80 °C.
(3) in compliance with applicable rules.
Water topping up
The chemical-physical properties of the system's water may alter
over time, resulting in poor operation or excessive topping up.
