Siemens LMU64 Series - Aqua-booster system

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Siemens Building Technologies Basic Documentation LMU54... / LMU64... CC1P7494en
HVAC Products 7 DHW control (BWR) 07.11.2002
• Instantaneous DHW heating system with plate heat exchanger (system 07)
• The plate heat exchanger is constantly maintained at the DHW comfort temperature
• Using comfort sensor B3, DHW demand is detected via dT supervision
• Outlet temperature control is accomplished with sensor B7
DHW demand is detected via dT supervision with sensor B3. Temperature control is
accomplished directly with sensor B7.
• With sensor B3 via dT supervision (parameter «dTzapfHz» in heating mode or
standby; parameter «dTzapfKomf» in comfort mode)
• Control sensor: Directly with return sensor B7 via PID control
• Boiler output: Modulating between minimum and maximum
• Setpoint: T_set_DHW, depending on the DHW compensation
variant (e.g. potentiometer, HMI, QAA73..., etc.)
• Differentials: «SdBwAus1», «SdBwEin1»
• With sensor B3 via dT supervision (parameter «dTzapfEnde»)
• Q1 / diverting valve are always in operation ( → DHW circuit)
The plate heat exchanger is constantly maintained at the DHW comfort temperature
using comfort sensor B3.
• When the DHW comfort temperature is not reached
• Control sensor: With comfort sensor B3
• Boiler output: Minimum (fixed value)
• Setpoint: Parameter «TbwBereit» (if «KonfigRg2.1 = 1»)
• Differentials: SdBwEin2, SdBwAus2Max
When the DHW comfort temperature is reached.
During comfort control:
• Q1 / diverting valve are always in operation ( → DHW circuit)
After comfort control:
• Relevant outputs are activated in the DHW / heating circuit ( è KonfigRg2.0)
− If «B2 > TqNach»: As long as «B2 < TqNach»
or
− If «B2 < TqNach»: For the fixed time of one minute
• To compensate a possible temperature offset, a setpoint readjustment for comfort and
outlet temperature control mode can be implemented:
− Parameters «dTbwKomfxx» for a setpoint of 40 °C / 60 °C in comfort mode
− Parameters «dTbwAuslxx» for a setpoint of 40 °C / 60 °C in outlet temperature
control mode
− In addition - as an option - an external DHW flow switch can be used to generate a
demand (parameter «KonfigRg8»)
Aqua-booster system
Hydraulic diagram
Operating mode
Outlet temperature control
DHW demand
Control
End of demand
Pump / diverting valve
overrun
Comfort control
DHW demand
Control
End of demand
Pump / diverting valve
overrun
Miscellaneous