63/130
Siemens Building Technologies
Basic Documentation RVD230
CE1P2383en
HVAC Products
16 Function block D.h.w. heating
27.05.2004
16.3 Control of the circulating pump
The function block controls a circulating pump, if present. The pump is optional with every
type of plant. The only exception is plant type 7–2, where the pump is controlled exter-
nally.
The circulating pump prevents the d.h.w. piping system from cooling down.
For the release of the circulating pump, the following settings can be made on operat-
ing line 102:
Setting Release
0
The circulating pump is always released (24 hours a day)
1
The release takes place according to the heating circuit program en-
tered on operating lines 6 through 12. There is no forward shift
2
The release takes place according to the d.h.w. program entered on
operating lines 17 through 23
On operating line 120, it is possible to select whether or not during d.h.w. heating the
control output shall be inactive:
Setting Release
0
OFF during d.h.w. heating
1
ON during d.h.w. heating
If the circulating pump is assigned to one or several heating programs, it immediately
starts running when the heating period begins. When, according to the d.h.w. assign-
ment, all heat consumers are in holiday mode, the circulating pump will be deactivated.
For more detailed information, refer to chapter 20 “Function block Assignment of d.h.w.
heating".
Speed control of the circulating pump is not possible.
16.4 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 set on operating line 103. It only acts with the plant
types that use a storage tank.
16.5 Legionella
function
The legionella function is described in chapter 18 “Function block Extra legionella func-
tions“.
16.6 Priority of d.h.w. heating
16.6.1 General
Depending on the amount of heat available, it may be practical to restrict the quantity of
heat delivered to the heating circuits during d.h.w. heating. That means that in this
case, d.h.w. heating is given priority over space heating. On operating line 106, the
controller offers 3 different types of priority:
•
Absolute priority
•
Shifting priority
•
No priority (parallel operation)
