Protection Against Discharging Of The D.h.w. Storage Tank; Maximum Duration Of D.h.w. Heating; Switching Differential Of D.h.w. Control; Plant Type No. 6B - Siemens RVD110 Basic Documentation

50/94
Siemens Building Technologies
HVAC Products
The legionella setpoint (input on operating line 105) will not be restricted by the maxi-
mum setpoint of the d.h.w. temperature.
The legionella function can only be interrupted by switching off d.h.w. heating alto-
gether.
14.4.5 Protection against discharging of the d.h.w. storage
tank
With plant types no. 2 and 8, d.h.w. heating features a protection against discharging
during pump overrun.
These 2 types of plant use 2 separate pumps, 1 for the heating circuit and 1 for d.h.w.
heating.
With plant type no. 3, the diverting valve will assume the position "Heating circuit".
If the flow temperature is lower than the d.h.w. temperature, overrun of the charging
pump will be stopped prematurely. This prevents the d.h.w. from cooling down unnec-
essarily.
Plant types no. 6 and 7 have no protection against discharging during pump overrun.
Overrun of charging pumps Q3 and Q7 will never be stopped since cooling down of the
d.h.w. heat exchanger is more important.
Plant type no. 7 features protection against discharging during d.h.w. heating. Pump Q7
stops when the common flow temperature B1 is lower than the storage tank tempera-
ture B71.

14.4.6 Maximum duration of d.h.w. heating

The duration of d.h.w. heating can be limited to make certain the heating circuit will
receive sufficient amounts of heat also when d.h.w. heating cannot be completed. The
input is made on operating line 109. If no maximum duration of d.h.w. heating is re-
quired, the function can be deactivated (setting - - - ).
When the maximum duration of d.h.w. heating is reached, d.h.w. heating will then be
locked for the same period of time.
This function is independent of the type of d.h.w. priority. It is not active with plant types
no. 4 and 5.

14.4.7 Switching differential of d.h.w. control

D.h.w. heating is switched off when the d.h.w. temperature has reached its setpoint. It
is switched on again when the d.h.w. temperature has fallen below the setpoint by the
amount of the switching differential.
The switching differential is to be entered on operating line 103. It is only active with the
types of plant that use a d.h.w. storage tank.
14.5

Plant type no. 6b

14.5.1 Layout

The RVD130 can also provide d.h.w. heating in plants in which the d.h.w. is heated
directly by the primary circuit of the district heating network. In that case, the heat ex-
changer only supplies heat to the heating circuit (also refer to plant type no. VG5b with
the RVP97).
The return from the d.h.w. circulating pump must be fed into the storage tank.
Basic Documentation RVD110, RVD130
14 Function block D.h.w. heating
CE1P2381E
27.05.2004