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Siemens Building Technologies Basic Documentation LMU54... / LMU64... CC1P7494en
HVAC Products 7 DHW control (BWR) 07.11.2002
The compensation mode of DHW heating depends on the plant components connected
to the LMU… . By evaluating the components, «Compensation variant Bw» will be
generated (refer to chapter «Compensation variant Bw»).
The setpoint used depends on the compensation variant:
Compensation
variant DHW
DHW release DHW setpoint Description
Locked 0 (always locked) TbwSmin
DHW heating is locked, the DHW setpoint
is initialized with the minimum setpoint,
no frost protection possible
Emergency
operation
1 (always released)
(TbwSmin+
TbwSmax)/2
Since there is no facility to set the DHW
temperature setpoint, the mean value of
the setpoint setting range is used
Fixed value
control
1 (always released) TbwSollMmi DHW setpoint of HMI will be adopted
DHW off Bw_Soll_Frost
DHW heating is locked
Frost protection for DHW is active
AGU2.310...-
dependent
DHW on
TbwSollMmiRed
TBwSollMmi
According to the switching program of the
AGU2.310...
Follows from RU
locked
TbwSmin
Adoption of frost protection setpoint from
the LMU...
RU-dependent
Follows from RU
released
TdhwSet DHW setpoint of RU will be adopted
RVA-dependent released TbwSollRva DHW setpoint of RVA will be adopted
The resulting DHW temperature setpoint will be limited to the permissible setting range.
The important criterion here is the type of system used - storage tank or instantaneous
heating system.
The setpoint setting range with storage tank systems follows from the parameterization
of the boiler and the DHW heating circuit:
TbwSoll
7494d17E/0201
TbwSmax
TbwSmin TbwSmax
TbwSmin
DHW
setpoint
limited
50 °C
Boiler temperature setpoint during storage tank charging
TbwSmin: Minimum DHW temperature setpoint
TbwSmax: Maximum DHW temperature setpoint
DHW temperature control
Compensation variants
Limitation of the DHW
temperature setpoint with
storage tank systems
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