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Siemens Building Technologies Basic Documentation LMU54... / LMU64... CC1P7494en
HVAC Products 3 Functions 07.11.2002
Based on the temperature demands of the connected pieces of equipment, the CM
determines the resultant boiler temperature setpoint or, in the case of instantaneous
DHW heating systems, the DHW temperature setpoint.
The resulting temperature demand is produced from the maximum generation of all
available and released temperature demands, depending on the selected priority:
• No priority: Resulting temperature demand = max. (temperature
demand «HC1», temperature demand «HC2»,
temperature demand «ext. HC», temperature demand
«Bwk»)
• Absolute priority or all systems with instantaneous DHW heaters
- With heating demand: Resulting temperature demand = max. (temperature
demand «HC1», temperature demand «HC2»,
temperature demand «ext. HC»)
- With DHW demand: Resulting temperature demand = temperature demand
«Bwk»
The result obtained from the maximum generation must be restricted to the boiler’s
permissible temperature range. Depending on the parameterization, this may have an
impact on the temperature demand from the individual circuits.
If parameterization is correct, the permissible boiler setpoint range and setting of the
temperature limiter look as follows:
TkIst
TkSoll
7494d12/0201
TkSmin
TkMax
TkSmax
Tstb
TkSmin TkSmax
Correlation between 2-position control and temperature limiter
As the graph shows, the following conditions must be satisfied:
TkMax < Tstb
TkSmax < TkMax
Determining the
temperature demand
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