Warning
Water quality has a significant impact on the lifetime and performance of a boiler's heat
exchanger.
Improperly prepared water in a heating circuit may cause damage to the heat exchanger
through fouling or corrosion. Repeated or uncontrolled water fills will increase the potential
for damage.
High levels of dissolved solids or minerals may precipitate out of the fluid onto the hottest part
of the heat exchanger, impairing heat transfer and resulting in overheating and premature
failure. The amount of solids that may form on the heat exchanger will depend on the degree
of hardness and the total water volume in the system. A high water volume system with a low
hardness count may cause as much damage as a system with less volume and higher
hardness, so it is recommended to treat water so as to reduce dissolved solids to the
minimum 10 ppm, and to no more than 30 ppm. Water chemistry allowable limits are as
follows:
TDS 0.6 to 1.75 grains/ gal (10 to 30 ppm)
Acidity pH is to be between 6.6 and 8.5
Chloride is to be less than 125 mg/l
Iron is to be less than 0.3 mg/l
Cu less than 0.1 mg/l
Conductivity is to be less than 400μS/cm at 77°F (25°C)
Important: Ensure that these limits are acceptable for the other water-side components in
the system.
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General