Water Quality For Primary (Space Heating / Cooling) And Secondary; (Dhw) Circuit - Hitachi YUTAKI S Series Installation And Operation Manual

5.3.3 Water quality for primary (space heating / cooling) and secondary

(DHW) circuit

!
CAUTION
• 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. If the results of the analysis are not good,
the use of industrial water would be recommended.
• No antifreeze agent shall be added to the water circuit in a split systems.
• To avoid deposits of scale on the heat exchangers surface it is mandatory to ensure a high water
quality with low levels of CaCO
Before water filling, sludge removal (for existing water networks), cleansing and rinsing (for an
existing or new installations water networks) it is important to cleanse all hydraulic pipes to
remove sludge and scale by using a specific designed product for cleaning central heating systems.
Also, its recommended to use a product inhibitor for protecting central heating systems against
limescale and corrosion, always following manufacturer's instructions and ensuring that the
product is suitable for the material used in the water network and the YUTAKI unit.
When using chemical treatments and inhibitors always follow manufacturer's instructions and
ensure that the product is appropriate for the total water system. Using filling water that does
not meet the stated quality requirements can cause a considerably reduce in service life. The
responsibility will be out of Hitachi warranties.
The following water quality minimum requirement:
Parameter
pH
Conductivity
Alkalinity
Total Hardness
Chlorine
Sulphate
Nitrate
Iron
TDS (Total dissolved solids)
Appearance of the water
PMEN0643 rev.0 - 04/2023
.
3
Parametric Value
6.5 to 8.5
10 ~ 500
60 ~ 300
6 ~ 15
0.6 ~ 1.5
60 ~ 150
< 50
< 50
< 100
< 0.2
8 ~ 400
Clear and without deposits
Unit
-
µs/cm
mg/l
ºf H
mmol/l
mg CaCO /I
3
mg CI /I
¯
(mg SO /l)
2-
4
mg/l (NO )
3
mg/l (Fe)
ppm
-
21
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