Siemens RVS41.813 - 6.19 Instantaneous DHW heater (only RVS61.843)

Transfer
Line no. Operating line
5130
Transfer strategy
Off ¦ Always ¦ DHW release
If the temperature level of the buffer storage tank is high enough, the DHW storage
tank can be charged by the buffer. Depending on the hydraulic circuit used, this heat
transfer can be accomplished either with charging pump Q3 or transfer pump Q11,
which is specifically parameterized for this function.
Transfer strat
egy
B3/B31 B4
Q11
6.19 Instantaneous DHW heater (only RVS61.843)
Overview
The controller supports DHW heating via an external heat exchanger. The heating
energy required is delivered by the buffer, DHW or combi storage tank.
A speed-controlled pump (left) or pump with fixed speed plus mixing valve (right) are
used to supply heat to the DHW circuit, depending on demand.
B38
T
Q34
FS
T
Y33/Y34
B38
Q34
FS
When the flow switch (FS) detects flow, sensor B38 ensures that the current DHW
nominal setpoint is maintained. But since heat losses across the external heat
exchanger always occur, parameter 5406 (Min setp diff to tank temp) is used to allow
an adjustable differential for sensor B38. In other words: The speed-controlled pump
(left) or the mixing valve (right) tries to reach or maintain the nominal setpoint minus the
setting of parameter 5406 at sensor B38. As soon as the flow switch detects no more
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Siemens Switzerland Ltd User manual RVS61.843, RVS41.813 CE1U2355en_02
HVAC Products 6 The settings in detail 28. September 2009