Viessmann VITOTRANS 353, Installation And Service Instructions Manual

Page: 23 / 52

23
Display Description Factory setting Setting range
"
Δ
T ON" Only for "Type" "Differential" :
Start temperature differential for
return stratification
"Differen-
tial"
10.0 K 0.5 to 20.0 K
"
Δ
T OFF" Only for "Type" "Differential" :
Stop temperature differential for
return stratification
"Differen-
tial"
6.0 K 0.5 to 20.0 K
Type of return stratification
2 function modes can be selected for return stratifica-
tion.
"Thermostat" :
■
Changeover between 2 cylinder areas or cylinders
by using the
"DHWcircRT sensor"
■
If "T ON" is exceeded at the "DHWcircRT sensor" ,
the return is fed into the upper cylinder area or the
hotter cylinder.
■
If the limit temperature "T ON" - "Hysteres." is not
reached at the "DHWcircRT sensor" (S4 or S6), the
return is fed into the lower cylinder area or the cooler
cylinder.
"Differential" :
■
Changeover between 2 cylinder areas or cylinders
by using the
"DHWcircRT sensor" and an addi-
tional cylinder temperature sensor (accessories)
■
If the temperature differential "
Δ
T ON" is exceeded
between the "DHWcircRT sensor" (S4 or S6) and
the cylinder temperature sensor (S5), the return is
fed into the upper cylinder area or the hotter cylinder.
■
If the "
Δ
T OFF" temperature differential is not
reached between "DHWcircRT sensor" and the cyl-
inder temperature sensor, the return is fed into the
lower cylinder area or the cooler cylinder.
Setting pasteurisation
Pasteurisation prevents the formation of legionella in
the DHW pipes and DHW circulation pipes of the heat
exchanger on the DHW side.
Requirements:
■
The "DHW circ." function must be enabled.
■
The heat generator must make a sufficient heat
amount available.
Note
DHW circulation remains continuously on during pas-
teurisation.
Procedure
The primary pump speed is regulated during pasteuri-
sation so that the adjustable
"T pasteu. set" tempera-
ture is maintained at the relevant "TDHW sensor"
(S2). Pasteurisation is successful if the "T pasteu.
set" temperature
–
5 K is exceeded at KS4 or S6 for
the period "Pasteu. dur." .
Once pasteurisation is complete, the results are shown
in the status messages; see page 25.
Pasteurisation in cascades
The set "Pasteu. dur." is split evenly between the cas-
cade modules.
Once pasteurisation is complete, the results are shown
in the status messages of the relevant cascade control
unit; see page 25.
Commissioning
Setting return stratification
(cont.)
5517 095 GB
Commissioning