Optimum Stop Control; Quick Setback; Optimum Start Control - Siemens RVD230 Basic Documentation

Siemens Building Technologies
HVAC Products

12.9.5 Optimum stop control

During the building's occupancy time, the RVD230 maintains the setpoint of normal
heating. Towards the end of the occupancy time, the control switches to the reduced
setpoint. Optimization calculates the changeover time such that, at the end of occu-
pancy, the room temperature will be 0.5 °C lower than the setpoint of normal heating
(optimum shutdown).
By entering 0 hours as the maximum optimum shutdown, optimum stop control can be
deactivated.

12.9.6 Quick setback

When changing from the normal temperature to a lower temperature level (reduced or
holidays / frost), the heating will be shut down. And it will remain shut down until the
setpoint of the lower temperature level is reached.
• When using a room sensor, the effective actual value of the room temperature is taken
into account
• When using no room sensor, the actual value is simulated by the room model
The duration is determined according to the following formula
T
Rw
t = 3 × k × (– ln
t
T
Rw
ln Natural logarithm
k Building time constant [h]
t
t Duration of quick setback [h]
T Composite outside temperature
AM
Setpoint of normal room temperature
T
Rw
Setpoint of reduced room temperature
T
Rw

12.9.7 Optimum start control

During the building's non-occupancy times, the RVD230 maintains the setpoint of re-
duced heating. Towards the end of the nonoccupancy time, optimization switches the
control to the normal setpoint. Optimization calculates the changeover time such that,
at the start of occupancy, the room temperature will have reached the setpoint of nor-
mal heating.
When the room temperature is simulated by the room model, that is, when using no
room temperature sensor, the forward shift in time is calculated as follows:
t = ( T - T ) × 3 × k
Rw RM
k Building time constant [h]
t
t Forward shift [min]
Setpoint of normal room temperature
T
Rw
T Room model temperature
RM
Optimum start control with the room model takes place only if, previously, quick setback
took place.
Optimum start control can be deactivated by entering 0 hours as the maximum heating
up period.
Basic Documentation RVD230
12 Function block Space heating
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CE1P2383en
27.05.2004