Hitachi YUTAKI S Series Instruction Manual page 29

REFRIGERANT AND WATER PIPING
4.4.5 Water quality
!
C A U T I O N
• Water quality must be according to EU council directive 98/83 EC.
• Water should be subjected to filtration or to a softening treatment with
chemicals before application as treated water.
• It is also necessary to analyse the quality of water by checking pH,
electrical conductivity, ammonia ion content, sulphur content, and
others. Should the results of the analysis be not good, the use of
industrial water would be recommended.
• No antifreeze agent shall be added to the water circuit.
• To avoid deposits of scale on the heat exchangers surface it is
mandatory to ensure a high water quality with low levels of CaCO

Recommendations for the DHW circuit
The following is the recommended standard water quality.
Item
supplied
Electrical Conductivity
(mS/m) (25°C)
{µS/cm} (25 °C)
(2)
Chlorine Ion (mg CI¯/I)
Sulphate (mg/l)
Combination of chloride and
sulphate (mg/l)
Total Hardness (mg CaCO /I)
3
?
N O T E
• (1): The mark " " in the table means the factor concerned with the
tendency of corrosion or deposits of scales.
• (2): The value shown in "{}" are for reference only according to the
former unit.
• (3): Water range will be according s/UNE 112076:2004 IN.
11 PMML0574 rev.0 - 09/2021
DHW
Tendency
(1)
space
Water Deposits
Corrosion
of scales
(3)
100~2000
max 250
max 250
max 300
60~150
4.4.6 Water filling
1 Check that a water check valve (ATW-WCV-01 accessory)
with a shut-off valve (field supplied) is connected to the
water filling point (water inlet connection) for filling the space
heating hydraulic circuit (see
2 Make sure all the valves are open (water inlet/outlet shut-off
valves and the rest of valves of the space heating installation
components).
3 Ensure that the air purgers of the indoor unit and installation
are open (turn the indoor unit air purger twice at least).
4 Check that the drain pipes connected to the safety valve
.
3
(and to the drain pan in case of installing the "Cooling kit"
accessory) are correctly connected to the general draining
system. The safety valve is later used as an air purging
device during the water filling procedure.
5 Fill the space heating circuit with water until the pressure
displayed on the manometer reaches approximately 1.8 bar.
?
N O T E
While the system is being filled with water, it is highly recommended
to operate the safety valve manually so as to help with the air purging
procedure.
6 Remove as much air from inside the water circuit as possible
through the indoor air purger and other air vents in the
installation (fan coils, radiators...).
7 Start the air purge procedure test. There are two modes
(Manual or Automatic) which helps in case of installations
with heating and DHW operation:
a. Manual: Start and stop the unit manually using the unit
controller (Run/Stop button) and also using the DSW4
pin 2 of the PCB1 (ON: Forced to derive to DHW coil;
OFF: Forced to derive to space heating).
b. Automatic: Select the air purge function using the
user controller. When the automatic air purge function
is running, the pump speed and the position of the
3-way valve (space heating or DHW) are automatically
changed.
Water
pump
ON
DHW
3Wv
OFF
8 If a little quantity of air is still remaining in the water circuit,
it will be removed by the automatic air purger of the indoor
unit during the first hours of operation. Once the air in the
installation has been removed, a reduction of water pressure
in the circuit is very likely to occur. Therefore, additional
water should be filled until water pressure returns to an
approximate level of 1.8 bar.
"4.4 Space heating and DHW").
Repeat...
Repeat...
Seconds
Seconds