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Siemens Building Technologies Basic documentation RVD240 CE1P2384en
HVAC Products 16 D.h.w. heating 27.05.2004
A temporary drop of the d.h.w. flow temperature is accepted. Heat losses are only par-
tially compensated for; the flow temperature may drop by a maximum of 20 %. Subse-
quent heating up to the d.h.w. setpoint always takes a minimum of 5 minutes.
For the compensation of heat losses, the circulating pump must be released. If it is not
released, no control is provided independent of the d.h.w. flow temperature.
D.h.w. setpoint T
BWw
= 50 °C
Cold water temperature T
Nx
= 10 °C (fixed value):
Permissible reduction
∆T = 20 %
Minimum d.h.w. flow temperature T
BWV
= ?
T
BWV
= T
BWw
– ∆T × (T
BWw
– T
Nx
) = 50 – 0.2 (50 – 10) = 42 °C
The aim is to maintain the d.h.w. setpoint and all heat losses will be fully compensated
for. A circulating pump is used.
16.3.7 Cold water sensor
Cold water sensor B32 is fitted after the mixing point of cold water return and circulation
return. It should be located as close as possible to the mixing point. The sensor detects
temperature changes on the cold water side, which are then included in the flow tem-
perature control. This improves the control performance considerably.
Setting 2
Example
Setting 3
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