Panasonic WH-UD05JE5 Service Manual page 183

18.1.4 Specifications
18.1.4.1 Specifications of fresh water was heat transfer medium in brazed heat
exchanger
Parameter Quality Limits for Tap Water on the Secondary Side
Temperature Below 60°C
pH 7 to 9
Alkalinity 60mg/l < HCO₃ < 300mg/l
Conductivity < 500μS/cm
Hardness [Ca⁺, Mg⁺] / [HCO₃⁻] > 0.5
Chloride < 200mg/l at 60°C
Sulphate [SO₄²⁻] < 100mg/l and [HCO₃⁻] / [SO₄²⁻] > 1
Nitrate NO₃ < 100mg/l
Chlorine < 0.5mg/l
18.1.4.2 External filter
Solids in the water must be filtered.
Minimum filter mesh size required for the field supply external filter in the water inlet is 20 mesh.
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