Hotpoint LTF11M121OUK Service Information page 17

Indesit Company
Water Softening and Regeneration
To obtain acceptable cleaning results, it is necessary to soften the washing water if the hardness is
above 7 Clarke. Without water softening, limescale deposits especially on glassware and the internal
dishwasher cavity would be noticed, also hard water would affect the performance of the powder or
tablet resulting in a reduced cleaning performance.
Water filling into the machine passes through the resin (ion exchange) container of the machines
water softening unit. This exchanges the hardness ions in the water for sodium ions which do not
affect the washing process. Eventually all the sodium ions in the unit will be replaced with hardness
ions.
To regenerate the water softener, a concentrated salt solution (sodium chloride) is passed through
the resin (ion exchange) unit.
Regeneration Procedure
Unlike previous models Regeneration is not carried out during every wash. The Control Module
counts the number of Litres used since the last Regeneration.
The volume of water (in Litres) used between Regeneration is dependant upon the Water Hardness
Setting stored in the Control Module. (Refer to "Setting the Water Hardness"). See Chart below.
Water Hardness Setting
1
2
3
4
5
Regeneration Sequence
1. Regeneration valve activated, after 2 seconds, the fill inlet solenoid is opened to allow water
flow, water flows from the inlet through the salt and the mixture of water and salt reaches the
resins.
2. Solenoid valve closes (the inlet valve and after 2 seconds the regeneration valve).
3. Pause for 10 minutes.
4. Fill with 190cc of water (same procedure as step 1.)
5. 5 minutes pause.
6. Starts resin wash. Between 1 and 2 litres of water flow directly through the resins. (Inlet valve is
on, regeneration valve is off.
7. Drains.
Note: It the water hardness is set to levels 4 or 5, between 5 and 10 minutes will be added to
the programme duration.
Low Salt Warning
An Optical sensor is fitted to the salt container where the presence of salt breaks the beam in
the sensor. When the level of salt is below the sensor level, the receiving sensor receives the
light beam from the sending Led.
The sensor position is not at the bottom of the salt container because of possible false readings
caused by impurities that collect in the bottom of the salt container.
The Low Salt warning lamp is switched on 6 washes after the sensor signals the module.
Service Manual UK
Regenerates Every...
150 litres
100 litres
65 litres
30 litres
15 litres
17 of 40
No water is stored for Regeneration
and regeneration will always take
place at the end of the last rinse,
after the number of litres has been
achieved.
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