 The pH should be kept between 6,5

 The pH should be kept between 6,5 and 8,5. Maximum allowable content of chlorides with respect to the aluminium heat exchanger is 250 mg/litre. Maximum allowable content of sulphate and nitrate is both 100 mg/litre, to limit the risk of microbiologically influenced corrosion (MIC). Strong oxidizing chemicals need to be avoided. Some examples, but not limited to, of oxidizers are: chlorine (Cl2), hydrogen peroxide (H2O2), bromine (Br2), ozone (O3),chlorine dioxide (ClO2), sodium hypochlorite( NaClO), potassium hypochlorite (KClO),chlorinated lime (Ca(ClO)2). Strong oxidizers are mostly added to the water as biocides for reducing the microbiological activity of the water. Strong complexing agents need to be avoided. The most likely to occur are: chlorides (Cl-), ammonia and ammonia containing chemicals (NH3, amines, EDTA, etc.), polyphosphates (like Calgon). Strong complexing chemicals are also known as“chelants” (like EDTA, NTA) and are widely used for controlling scaling by forming heatstable soluble complexes typically with calcium and magnesium. The installation should be designed in such a way that all air can be purged, assure that after installation all air is purged. Preferably also install air separators. At total hardness of 11 ºd or 11°dH (~ 2 mmol/litre), the total volume VT of filled, refilled and topped up water during the lifetime of the boiler, must not exceed following values: 20 litres/kW x [kW] for C930 boilers.Taking into consideration that, during the life time of the heat exchanger, the water in the installation will probably be topped-up several times, therefore the maximum values in practice must not exceed following values ; 10 litres/kW x [kW] for C930 boilers.