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1.9 Hydraulic system
Limescale and other chemical substances in the water can
solidify producing incrustations. To prevent this happening,
equip the system with a closed expansion tank. The water that
goes into the closed expansion tank does not evaporate and is
not dispersed. In this way the level of water in the system is
kept constant and it will not be necessary to add fresh water.
In addition, limescale and dust do not form and the system will
have a longer life.
− The water circulating in the system is not to be used for
washing or drinking.
− Do not take water from the system. If the water level is
low, top it up.
− To prevent damage due to limescale or chemical residues,
put water in the system with the following recommended
values: pH > 7.2 TH <25 °Fr. Check the water quality, and if
the quality of the water used does not meet the required
standards, subject the water to suitable corrective pro-
cesses to obtain the desired quality.
− To prevent the formation of limescale or sediments inside
the boiler or their passage from the boiler to the hydraulic
system, equip the system with suitable protections both
inside and on the outside.
− Connect the circulation pump to the boiler water outlet.
The power of the pump should be suitable for the boiler.
− Provide a 4-way mixing valve or a pump on the by-pass
section activated by a thermostatic control to raise the
temperature of the water in the return line.
− Provide a 3-way motorised valve connecting the supply
line and the return line of the heating system, to adjust
the flow rate of the water in the system according to the
desired performances.
− The amount of water in the system should be such that
there is always water in the boiler. Otherwise the boiler
could be subject to corrosion. If the boiler is not used in
winter, in order to prevent damage from freezing, use an
anti-freeze product, periodically measure the amount of
1.10 Schematic diagram - system for heating and domestic hot water production
DOMESTIC
WATER
UTILITIES
3
4
5
3
12
10
3
15
13
SYSTEM
OUTLET
3
5
4
3
3
3
4
5
3
17 5
3
EAF
6
14
10
3
15
3
3
EAF
8
DISCHARGES
water in the boiler with a pressure gauge if it has a closed
expansion tank or with a water gauge if it has an open
expansion tank.
pH
Electrical conductivity
Chloride ions
Sulphuric acid ions
Total iron
M alkalinity
Total hardness
Sulphur ions
Ammonia ions
Silicon ions
The Thermostat (1) should be installed at a distance of 3-5 diam-
eters from the connection point to the return line.
SYSTEM
RETURN
LINE
3
2
2
3
7
6
3
11
DISCHARGES
10
REFERENCE VALUES
less than 7.2
less than 200 μs/cm (25°C)
less than 50 ppm
less than 50 ppm
less than 0.3 ppm
less than 50 ppm
less than 25° F
none
none
less than 30 ppm
1
D
1
Boiler
2
System manifolds
3
Shut-off valves
4
System pumps
5
Non-return valves
6
Automatic vent valve
7
Boiler safety valve
8
Boiler discharge tap
9
Storage heater safety valve
10 Charging the system
11
System expansion tank
12 Storage heater
13 Storage heater discharge tap
14 Domestic hot water expansion
tank
15 Softener filter
16 Pressure reducer
17
Condensation pump
1
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