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7.4.2 Water
treatment
The system should be filled with mains cold water (for the UK this will usually have a
pH of between 7 and 8).
Pressurised installations with a boiler/system content ratio of 1:10 or less should not
require water treatment, provided that the following conditions apply:
- The system is flushed thoroughly to remove all fluxes and debris and filled
completely once.
- Make up water is limited to 5% per annum.
- The hardness of the water does not exceed 360 ppm (20°D).
All scale deposits will reduce the efficiency of the boiler and should be prevented.
However provided the above is complied with any scale produced will not be too
detrimental to the boiler efficiency and will not reduce the anticipated life expectancy of
the boiler.
NOTE
: Scale deposits in excess of 5 mm will reduce boiler efficiency and increase the
risk of premature casting failure.
As most systems contain a variety of metals, it is considered good practice to provide
some form of water treatment (especially in open vented systems) in order to prevent
or reduce the following:
- Metallic
corrosion
- Formation of scale and sludge
- Microbiological
contamination
- Chemical changes in the untreated system water
Suitable chemicals and their use should be discussed with a specialist water treatment
company prior to carrying out any work (environmental aspects, health aspects).
The specification of the system and manufacturers recommendations must be taken
into account, along with the age and condition of the system. New systems should
be flushed thoroughly to remove all traces of flux, debris, grease and metal swarf
generated during installation. Care to be taken with old systems to ensure any
black metallic iron oxide sludge and other corrosive residues are removed, again by
thoroughly flushing, ensuring that the system is drained completely from all low points.
NOTE:
Please ensure that the new boiler plant is not in circuit when the flushing takes
place, especially if cleansing chemicals are used to assist the process.
IMPORTANT:
Under no circumstances is the boiler to be operated with cleaning
chemicals in the system
.
