What is a water softener?

To make water "soft", i.e. to reduce the concentration of calcium and magnesium salts, a water softener is used.

It is made up of a cylinder containing ion exchange resins which continuously exchange Calcium and Magnesium Ions with Sodium Ions. The resins contain the sodium ion within their lattice which is continuously released as the water passes through. The sodium ion then passes into the water, which becomes "softened", the calcium and magnesium ions are replaced by sodium inside the spheres. When all the sodium ions contained in the resins have been exchanged and therefore the resins have been totally deprived of them, regeneration becomes necessary in order to enrich them with sodium again and put them in a position to provide more softened water.

Regeneration of the resins of a water softener

The resin regeneration process can take place thanks to the special automatic valve and the sodium necessary to regenerate the resins is supplied by the "softening salt" (sodium chloride NaCl).

Timed Regeneration

It is the start of regeneration carried out after a set time. In fact, the valve has a programmer and a 24-hour daily timer. By setting the current time, it generally carries out regeneration at 02.00 on the selected day.

Volumetric Regeneration

It is a more economical and precise management system, as it carries out regeneration after the volume of water actually supplied. In fact, the valve has a counter, which counts all the liters of water dispensed and prepares the regeneration of the resins upon consumption (Cyclic). There are various volumetric regeneration options: immediate, delayed, forced regeneration delayed at the desired time, every 4 days when there is no water consumption or when the volume of water used in 4 days is not enough to start a volumetric regeneration.

What is the cycling capacity of a water softener

The cyclic capacity is the quantity of treated water (expressed in m°f) that the softener can supply between one regeneration and another. We recommend always taking this comparison into consideration when making calculations to determine the cycles.

To determine how much treated water (in m3) a softener can provide, divide the cyclic capacity by the hardness of the water to be treated. 

Example:

cyclic 75 m3 °f / 30 °f = 2.5 m3.

The softener provides 2.5 m3 of softened water with each regeneration.

Choosing the most suitable water softener model

To choose a water softener simply follow the following instructions:

You must take into account:

  • Daily water consumption (estimate)
  • Hardness of the water to be treated
  • Peak hourly flow

Since we cannot know the daily consumption, we can estimate the typical consumption of a house or condominium by multiplying the number of people by 160~200 liters per person (national average) so as to obtain, approximately, the daily consumption. The m3 of daily consumption is then multiplied by the hardness of the incoming water. The value obtained must be multiplied by 3 (average regeneration frequency valid for single- or two-family homes) and/or by 2 if condominiums.
Example:

Family of 5 people with water hardness 30 °f.

5 * 200 liters per person = 1 m3/day 1 m3/day x 40 °f = 40 m3/°f 40 * 3 = 120 m3/°f

We search the technical data sheets for the model with the cycle that is closest to the value of 120 m3/°f and/or higher. In this case it is the AC25F56D model which has a Cyclic of 125 m3/°f. At this point we check whether the water softener has sufficient flow rate.

The table shows a Max flow rate of 2.2 m3/h (2,200 l/h) therefore, based on the number of water withdrawal points considered: 2 Bathrooms + 1 Kitchen + 1 Garage will give:

600 l/h * 2 = 1200 l/h + 800 l/h + 600 l/h = 2600 l/h

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Water hardness: characteristics and risks

Most of the a which contains a certain quantity of dissolved salts which determines its so-called salinity. In particular, the hardness of water is given by the quantity of calcium and magnesium salts present in it. Hardness is expressed in French degrees (°f) and 1°f is equivalent to 10 mg/l of calcium carbonate (CaCO3) , i.e. 10 g/m3 of CaCO3; water without hardness (for example distilled water) has a hardness of 0°f.

It is possible to classify waters based on the following values:

  • Fresh water: from 0 to 5 °f
  • Medium Hardness Water: from 6 to 15 °f
  • Hard Water: from 16 to 30 °f
  • Very hard water: over 30 °f

The problems caused by excessive hardness are various and affect both the domestic and industrial sectors.

Hard water can block pipes and prevent soap from dissolving, and pose a high risk of deposits forming in domestic water systems. Due to the formation of these obstructions, the pipes become clogged and the efficiency of the boilers and tanks is reduced. This increases the cost of home water heating by approximately 15-20%. Another negative effect of such deposits is the damage to household machinery such as washing machines.

Softening water means increasing the life of these machines and their pipes, also contributing to better operation and a longer life of solar heating systems, air conditioning units and many others applications that use water for their operation.

Finally, it is imperative to remember the effects of excessively hard water on human health. In addition to the difficulties that children and the elderly may encounter in terms of digestibility, it should not be overlooked how hard water can favor the onset of kidney stones in predisposed subjects.

N.B. Another effect of softening is the removal of iron ions: the resins used in softeners can remove up to five milligrams per liter (5 mg/l).

Recommended hardness:

  • For food use: max 15 °f (Ministerial Decree 443 of 12/21/90)
  • For Steam Boilers: from 0 °f – 0.5 °f
  • For Textile Industries: 0 °f
  • For canning industries: from 0 °f to 5 °f
  • For industries in general: in any case lower than 10 °f
  • For cattle farms: from 10 °f to 15 °f

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