Domestic hot water
Attention!
The setting values for domestic hot water can be freely selected
within a wide range. Please ensure that the selected settings
correspond to the user requirements. Excessively high settings
may lead to scalding!
Legionnaires’ disease is transmitted by bacteria in drinking wa-
ter (legionella) and causes tubercular illnesses. It gets its name
from a convention attended by veterans of the US American Le-
gion in Philadelphia in 1976. Of the 4000 present, 220 people
contracted the disease which proved fatal for thirty of them.
The DVGW in Germany has introduced some recommendations
for the prevention of legionella in the drinking water of large sy-
stems (hotels, schools, hospitals etc.)
•
T
WS
= 60 ° C, X
Sd
(w) <= 5K (see SERV 90...94)
•
The entire hot-water system should be charged at least
once a day.
•
The circulation pump for domestic hot water (DHW)
should not be idle for more than eight hours per day; on
the contrary, its continuous operation is recommended.
If a 2-point output is used for the control of the DHW circulation pump, then (for
large systems) we recommend SERV 04...07 =+0 instead of SERV 04...07 = +4
for the time channel to the exterior.
See DVGW sheet W552 for advice on treating contaminated systems. Apart from
thermal treatment, other methods should also be considered.
SERV setting value
No.
Function
89
–1
Adaption of heating characteristic 2 (heating circuit 2)
–1
Adaption disabled
0
9
0
9
0
9
Adaption enabled, all 3 values are initially adjusted with the highest possible influence
Adaption enabled, all 3 values are from the beginning adjusted with the lowest
possibile influence
Counter for number of adaptions steps "extraneous heat" (0...9)
(for higher outdoor temperature)
Counter for number of adaptions steps "curvature" (0...9)
(for medium outdoor temperature)
Counter for number of adaptions steps "slope" (0...9)
(for low outdoor temperatures)
With each adaptation step, the corresponding counter is incremented by 1 (check). The SERV 88 value
can be changed manually at any time by entering a value between 000...999 in order to set new initial
conditions for the influence of the adaptation steps.
(–1...999)
!
SERV setting value
No.
Function
90
55
Domestic-hot-water setpoint T
WS
(0...69) (° C)
91
60
Flow-temperature setpoint T
FS(WS1)
for domestic-hot-water tank heating. Flow temperature is controlled to
this temperature for tank heating
(0...95) (° C)
92
60
Second domestic-hot-water setpoint T
WS2
(anti-legionella function)
(0...89) (° C)
93
65
Flow temperature setpoint for domestic-hot-water tank heating to the second setpoint T
FS(WS2)
.
(0...95) (° C)
94
8
Switching differential of the domestic-hot-water tank X
sd(w)
The tank is charged: when the actual value falls below the setpoint by the value entered for the switching
differential X
sd(w)
; and if charging is permissible according to the operating status
(1...19) (K)
R
–
47
–
7 000458 003
