ITR Hurricane Zephyr HW, Инструкция по установке и эксплуатации

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Section 11, Maintenance
International Thermal Research 11 - 5
and scale inhibitors added to "fresh" boiler fill water can act as
low cost "insurance" for hydronic systems.
Causes of Scale
Tap water is the most typical source selected for boiler fill water.
Water contains dissolved solids such as magnesium and calcium
which when heated becomes much less soluble and forms scale.
Scale comes out of solution in the largest amounts where the
temperature is highest in the system (i.e., the boiler heat
exchanger). As the scale builds up, noise and cold spots develop
since scales plug up water channels and acts as an insulator that
impedes proper heater transfer.
Acidity and Corrosion
Corrosion is the result of metal oxidizing (that is, metals reacting
with oxygen-rich boiler fill water). The acidity of any liquid
(including water) is a good indicator of how much corrosion will
actually take place. As a rule of thumb, boiler fill water should
have a pH greater than 7 and less than 10.5. The key to
preventing corrosion is to make sure that the heating system is
free of leaks and there is no need to replace it with fresh, oxygen
rich boiler fill water. Corrosion inside a hydronic heating system
stops quite quickly as the fill water stabilizes and becomes
oxygen-starved. The pH should be measured at least annually.
Since most hydronic heating systems are comprised of different
metals (e.g., iron, copper, etc.), and since boiler fill water is an
electrolyte (that is, it will conduct electrical current), electro-
chemical reactions ("galvanic" reactions) can take place. As the
fill water stabilizes, however, it becomes a very weak electrolyte,
so galvanic corrosion rarely becomes a problem - as long as the
system remains leak-free.
Preventative Treatments
Corrosion and scale inhibitors are relatively inexpensive. Ideally,
they should be applied only once, at the time of a new
installation or whenever a system has been completely drained.
Boiler water treatment specialists agree that the prevention of
leaks and the elimination of the need for frequent boiler water
make-up are top priorities for hydronic systems.