Miele G 7881 Service Manual

							2.2 Connection to a Shutoff Valve with Spring-Loaded Valve
Fig. 2:Shutoff Valve with WaterProof Valve
–Correct function
If the on-site shutoff valve contains a spring-loaded valve (041 Fig. 2, Pos. 2),
then, even if the valve is opened, the spring can hold the valve plate closed if the
counter pressure at the valve exit (041 Fig. 2, Pos. 4) is the same as that of the
supply. When both valves in the WaterProof system open, the supply pressure
can open the valve plate (041 Fig. 2, Pos. 2) against the spring pressure and
supply water can flow into the machine.
–Faulty function
If, e.g., a mixer tap located above the shutoff valve, 041 Fig. 2, Pos. 1, is closed
very quickly, a short high-pressure pulse (pressure hammer) develops in the
water supply and is exerted in all directions. This pressure also develops in the
chamber (041 Fig. 2, Pos. 3) if the shutoff valve is open and here the spring
closes the pressure plate before the pressure can disperse. Now the valves in the
double solenoid valve cannot open against this high pressure and water cannot
flow into the machine.
Descriptive Technical Documentation
041-4 DTD no. 62-7881
This information should not be duplicated or passed on without Miele approval. All rights reserved. 18.09.2013, US_am 
						

							x
Note
Miele washer-disinfectors are approved by the German water authority (shown
by the DVGW certification). Shutoff valves with spring-loaded valve plates are
therefore not required and can, if necessary, be replaced with non-spring-loaded
versions.
2.3 Water Paths
x
Fig. 3:Water Paths–24-Inch Machine with the Maximum Number of Options
1 Non-return device
2 Softener reactivation reservoir
3 Cabinet
4 Water intake - Soft water from softener
5 Flow meter
6 Water inlet valve - Demineralized water
7 Water inlet valve - Hot or cold water
8 Non-return valve
9 Water softener - Soft water outlet
10 Water softener - Supply water intake
11 Salt container intake
12 Salt container
13 Water inlet valve - Cold water
14 Condensate collector
15 Condensate drain pump
16 Heat exchanger plate
17 Steam intake
18 Steam condenser
19 Reactivation valve
Descriptive Technical Documentation
DTD no. 62-7881 041-5
18.09.2013, US_am This information should not be duplicated or passed on without Miele approval. All rights reserved. 
						

							x
Fig. 4:Water Paths–28-Inch Machine with the Maximum Number of Options
1 Non-return device
2 Softener reactivation reservoir
3 Cabinet
4 Water intake - Soft water from softener
5 Flow meter
6 Water inlet valve - Demineralized water
7 Water inlet valve - Hot water
8 Non-return valve
9 Water softener - Soft water output
10 Water inlet valve - Cold water
11 Water softener - Supply water intake
12 Salt container intake
13 Salt container
14 Water inlet valve - Cold water for steam condenser
15 Non-return valve
16 Condensate drain pump
17 Air intake - Drying unit (TA)
18 Steam intake
19 Steam condenser
Descriptive Technical Documentation
041-6 DTD no. 62-7881
This information should not be duplicated or passed on without Miele approval. All rights reserved. 18.09.2013, US_am 
						

							2.4 WaterProof System
x
Fig. 5:WaterProof System
Two independently functioning solenoid valves in the intake hose are combined to
form the WPS valve, e.g., Y1 (cold water), Y12 (hot water) and/or Y20
(demineralized water). The two valves located directly at the shutoff valve
connection are connected in series, both electrically and for water flow. This
ensures that if one valve should fail (e.g., due to blockage caused by a foreign
object) the water flow can still be switched off by the other valve if necessary.
Float switch B8/3, located in the drip pan under the machine, also forms part of
the system; see 050 2.6.1 Float Switch B8/3.
x
Warning!
The WaterProof system only operates with the door closed and the machine
switched on.
Descriptive Technical Documentation
DTD no. 62-7881 041-7
18.09.2013, US_am This information should not be duplicated or passed on without Miele approval. All rights reserved. 
						

							2.5 Water Intake, Water Diverter
Fig. 6:Water Diverter
In accordance with DVGW guidelines, the water diverter is provided with a non-
return device which prevents the possibility of a reflux of water back into the
supply should a vacuum exist.
The water intake hose from the WaterProof System (WPS) (cold/hot water) is
connected to the water diverter (041 Fig. 6, Pos. 14). Hard supply water flows past
the non-return valve (041 Fig. 3, Pos. 8) via flow meter 1B3/4 (041 Fig. 3, Pos. 5)
through the intake channel (041 Fig. 6, Pos. 2) past the ball valve (041 Fig. 6, Pos.
6) into the water diverter. Here a small proportion of the water passes through
small bypasses in the ball valve to the water reservoir (041 Fig. 6, Pos. 7) for later
use for softener reactivation. When this reservoir is full, excess water flows past
the overflow (041 Fig. 6, Pos. 8) directly into the cabinet. The proportion of supply
water to soft water is approximately 3 to 8 percent.
x
Note
After softener reactivation, the reservoir is filled again by the time the third water
intake has taken place.
Descriptive Technical Documentation
041-8 DTD no. 62-7881
This information should not be duplicated or passed on without Miele approval. All rights reserved. 18.09.2013, US_am 
						

							The majority of the water, blocked by the ball valve at the water reservoir inlet,
flows via the water channel (041 Fig. 6, Pos. 3) downwards to the water diverter
outlet (041 Fig. 6, Pos. 13) and then to the water softener (041 Fig. 3, Pos. 10).
After passing through the water softener, the now-soft water flows via the soft
water intake (041 Fig. 6, Pos. 10) back into the water diverter. It then flows into the
cabinet via the water intake (041 Fig. 3, Pos. 4) into the cabinet. Cabinet
ventilation is ensured via the opening (041 Fig. 6, Pos. 9).
If the washer-disinfector is connected to a demineralized water supply, this does
not pass through the softener; instead, it flows via the water diverter intake (041
Fig. 6, Pos. 11) directly into the cabinet. A dedicated flow meter (2B3/4) monitors
the quantity taken in.
2.6 Water Softener, Reactivation
2.6.1 Softener Block
x
Fig. 7:Water Softener with Additional Electrical Components
1 Salt container reed switch B8/2
2 Float with cap (in salt container) - Activates reed switch B8/2
3 Salt container
4 Soft water exit
5 Ion exchanger
6 Intake for water for reactivation from reservoir in water diverter
7 Supply water intake
8 Reactivation solenoid Y38 (230VAC)
2.6.2 Softener Reactivation, Reactivation Cycles
Reactivation of the ion exchanger depends on the set supply water hardness level
(programmable function E 01, 070 2.8.1E 01, Program-Independent Functions)
and the quantity of water taken in registered by the flow meter (consumption-
linked reactivation). The total quantity of hot and cold water taken in over a period
of time is registered by flow meter 1B3/4, recorded by the electronic and
Descriptive Technical Documentation
DTD no. 62-7881 041-9
18.09.2013, US_am This information should not be duplicated or passed on without Miele approval. All rights reserved. 
						

							compared with a reactivation table (041 Table 3) stored in memory. The quantity
of demineralized water taken in, registered by flow meter 2B3/4, is not taken into
account because this water does not pass through the water softener.
For reactivation the electronic activates solenoid valve Y38 (041 Fig. 7, Pos. 8).
Supply water from the reservoir (041 Fig. 7, Pos. 6) in the water diverter then flows
into the salt container where it dissolves a quantity of salt. The brine then flows
past a mechanical non-return valve into the ion exchanger and flushes the water
already present there into the sump. The built-in non-return valve in the softener
prevents the brine from mixing with the incoming supply water during normal
wash cycles. The brine flushes the resin in the ion exchanger and replaces the
retained calcium and magnesium ions (the hardness constituents previously
removed from the hard water) with sodium ions.
The salt in the salt container is sufficient for several reactivation cycles as it is not
all dissolved at once. The saturation point, above which the water cannot dissolve
any more salt, is approximately 40 percent. As the quantity of salt in the salt
container diminishes, the concentration of the brine decreases, and when a
certain minimum concentration is reached, the float with magnet activates the
reed switch (041 Fig. 7, Pos. 1). TheSalt(k) LED then lights up.
x
Water Hardness Setting, °d (Degree of
German Hardness)Total Water Quantity After Which Reactivation
Will Occur (Gallons (Liters))
0 No limitation (only without softener)
1 - 4 185 (700)
5 165 (625)
6 151 (570)
7 137 (520)
8 125 (475)
9 116 (440)
10 108 (408)
11 101 (382)
12 94 (356)
13 88 (332)
14 82 (309)
15 76 (287)
16 70 (266)
17 65 (246)
18 60 (227)
19 55 (210)
20 51 (194)
21 48 (182)
22 45 (171)
23 42 (160)
24 40 (150)
Descriptive Technical Documentation
041-10 DTD no. 62-7881
This information should not be duplicated or passed on without Miele approval. All rights reserved. 18.09.2013, US_am 
						

							Water Hardness Setting, °d (Degree of
German Hardness)Total Water Quantity After Which Reactivation
Will Occur (Gallons (Liters))
25 37 (140)
26 35 (131)
27 32 (122)
28 30 (113)
29 28 (105)
30 25 (96)
31 24 (91)
32 23 (86)
33 22 (82)
34 21 (78)
35 20 (74)
36 18 (70)
37 17 (66)
38 16 (62)
39 16 (59)
40 15 (56)
41 14 (53)
42 13 (51)
43 13 (50)
44 13 (49)
45 - 60 13 (48)
Table 3:Reactivation Showing Relationship Between Water Hardness and Water Quantity
In normal operation, reactivation (if required) is performed after the end of the
water intake step of the last main wash block HR 1 or HR 2. In chemical
disinfection programs (CH-DESIN), it takes place before the first wash block,
during heating, at the same time as the exposure time. Flushing the remaining
brine from the softener is carried out after the machine has completely drained at
the end of one of the named wash blocks.
If, due to a high set water hardness level or a high water consumption, the
reactivation cycle operating in parallel to the wash steps in the area of HR 1, HR
2, or CH-DESIN (G 7882 only) is not sufficient, an additional reactivation will be
performed at the start of the next program. The draining time at program start is
then extended to 150 seconds. If a steam condenser is installed, the condensate
drain pump is switched off after 1 minute. During the contact time (2.5 minutes),
no other component is active.
Descriptive Technical Documentation
DTD no. 62-7881 041-11
18.09.2013, US_am This information should not be duplicated or passed on without Miele approval. All rights reserved. 
						

							Reactivation takes place in 7 steps:
–2.5 minutes of brine flowing into ion exchanger.
–2.5 minutes of contact time for brine in ion exchanger.
–Flushing with 0.4 gallons (1.4 liters) of cold water followed by 10 seconds of
drainage.
–Flushing with 0.4 gallons (1.4 liters) of cold water followed by 10 seconds of
drainage.
–Flushing with 0.4 gallons (1.4 liters) of cold water followed by 10 seconds of
drainage.
–Flushing with 0.4 gallons (1.4 liters) of cold water followed by 30 seconds of
drainage.
–Flushing with 0.4 gallons (1.4 liters) of cold water followed by 50 seconds of
drainage.
2.6.3 Water Hardness Conversion Chart
x
Grains Per Gallon (gpg) Parts Per Million (ppm)
6 107
7 125
8 143
9 160
10 179
11 196
12 214
13 232
15 268
17 304
19 339
22 393
24 428
28 500
32 571
38 678
48 857
71 1267
Table 4:Water Hardness Conversion Chart
Descriptive Technical Documentation
041-12 DTD no. 62-7881
This information should not be duplicated or passed on without Miele approval. All rights reserved. 18.09.2013, US_am 
						

							2.7 Flow Meter
The incoming water rotates an impeller in the flow meter. A permanent magnet
located in the flow meter axle activates an external reed switch each time the axle
rotates. The pulses supplied by the reed switch are registered by the electronic.
Approximately 200 pulses represent 0.3 gallons (1 liter) of water. An adjustment of
the number of pulses perliteris not possible. If the flow count is not satisfied after
5 minutes, then the machine will fault out. There is also an overflow level control.
x
Fig. 8:Flow Meter Components
1 Circuit board (PCB) with reed switch
2 Housing
3 Permanent magnet
4 Impeller
5 Housing cap
Descriptive Technical Documentation
DTD no. 62-7881 041-13
18.09.2013, US_am This information should not be duplicated or passed on without Miele approval. All rights reserved.