Fisher & Paykel DishDrawer DD60 Service Manual page 33

4 TECHNICAL OVERVIEW
4.15 Water Softener ( some markets only)
The Water Softener uses a softening material (resin) to prevent most of the elements that cause hard
water from being present in the wash water. The resin can only treat a limited amount of water before
it needs to be regenerated. Regeneration is achieved by pumping salty water (brine) through the
resin, and flushing away the hard elements to the drain. The process of delivering softened water, and
regeneration of the resin is controlled by the electronic controller.
Delivering Softened Water: - Supply water arrives from the inlet valve then through an inline Strainer
to remove large deposits. The strainer is attached to the water softener by an inlet spigot.
Strainer Spigot
Strainer
In the water softener the water passes through an air break and a diverter valve. It is then either
directed through the resin to the dispenseras softened water, or directly to the dispenser, then into
the tub.
The electronic controller measures the volume of water treated soft water, and adds an appropriate
amount of non-treated hard water, to deliver a mix that is at the required hardness according to a
pre-determined schedule. Water is treated according to its supply hardness. The customer is able to
select one of 5 supply hardness settings in option adjustment mode.
Regeneration:- Regeneration is triggered when the amount of water that has been treated since the
last regeneration nears the capacity of the water softener. The quantities treatable for each of the
five settings of supply hardness have been predetermined, and are stored in the electronic controller.
When triggered, immediately after filling for the main wash, the brine pump is activated and delivers a
volume of salty water into the resin, at an amount appropriate to the hardness setting. The frequency
of the pump is 3 Hz, and makes a slight rattling sound. Later in the wash cycle, the resin is flushed
with supply water, and the by-products of regeneration are delivered into the wash water, and drained
with it away to waste. During the flush the fill valve turns on and off alternately for 5 seconds for
a number of times depending on the hardness setting. Normal treatment of incoming water then
resumes.
Salt:- The customer is required to fill the salt tank with dishwashing salt from time to time. Salt
is used in the water softener by mixing it with water to produce the salty water (brine) used in
regeneration. When the salt level is low, a salt level detector causes a glowing red light to appear
in the salt bung, and a "Salt" symbol appears in the LCD if one is fitted. When this happens, the
customer should remove the salt bung, and using the salt container provided, pour salt into the salt
reservoir until salt can be seen at the opening. The "Salt" symbol on the LCD will disappear and the
red light will not be visible when the salt tank bung is replaced. In areas where the supply water is
moderately hard, 21 dH (degrees of hardness) or 375 parts per million, water softener setting 3) the
salt reservoir will need to be filled about once a month, and in harder areas more frequently. Delivery
of treated water from one fill of the salt reservoir:
240 litres (63 gallons) at 30 – 100 ppm from 375 ppm supply water (setting 3)
144 litres (38 gallons) at 30 – 100 ppm from 625 ppm supply water (setting 5)
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