Siemens LMS14 User Manual

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Building Technologies Division User Manual LMS14... CC1U7471en
6 The settings in detail 07.05.2014
6.5.16 Quick setback
Line no. Operating line
HC1 HC2 HC3
780 1080 1380 Quick setback
Off
To Reduced setpoint
To frost Prot setpoint
During quick setback, the heating circuit pump is deactivated and, in the case of mixing
valve circuits, the mixing valve is fully closed.
Note!
Function Continuous pump operation enables the heating circuit pump to keep
running during quick setback also.
Note!
When frost protection for the plant is active, the heating circuit pump is switched on.
The process of switching on the heating circuit pump can result in rapid cooling.
 Function with room sensor:
When using the room sensor, the function keeps the heating switched off until the
room temperature drops to the level of the Reduced setpoint or the Frost protection
level. When the room temperature falls to the Reduced or Frost protection level,
the heating circuit pump is activated and the mixing valve released.
 Function without room sensor:
Quick setback switches the heating off for a certain period of time, depending on
the outside temperature and the building time constant.
The duration of quick setback can be calculated as follows:
t = 3 * building time constant * ln ((Comfort setpoint – composite outside temperature)/
(Reduced setpoint – composite outside temperature)
Example:
Duration of quick setback when Comfort setpoint – Reduced setpoint = 2 °C
(e.g. Comfort setpoint = 20 °C, Reduced setpoint = 18 °C).
Composite
outside
temperature
Building time constant
0 2 5 10 15 20 50
15 °C 0 3.1 7.7 15.3 23 30.6 76.6
10 °C 0 1.3 3.3 6.7 10 13.4 33.5
5 °C 0 0.9 2.1 4.3 6.4 8.6 21.5
0 °C 0 0.6 1.6 3.2 4.7 6.3 15.8
-5 °C 0 0.5 1.3 2.5 3.8 5 12.5
-10 °C 0 0.4 1 2.1 3.1 4.1 10.3
-15 °C 0 0.4 0.9 1.8 2.6 3.5 8.8
-20 °C 0 0.3 0.8 1.5 2.3 3.1 7.7
Duration of quick setback in hours
Duration of quick setback when Comfort setpoint – Reduced setpoint = 4 °C (e.g.
Comfort setpoint = 20 °C, Reduced setpoint =16 °C)
Quick setback

Siemens LMS14 Specifications

General

Brand	Siemens
Model	LMS14
Category	Control Unit
Language	English