Optimum Start Control; Boost Heating - Siemens RVL471 Basic Documentation

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Siemens Building Technologies
HVAC Products
10.4.7

Optimum start control

During the building's non-occupancy times, the RVL471 maintains the setpoint of
REDUCED heating. Toward the end of the non-occupancy time, optimization switches
the control to boost heating. This means that the selected boost will be added to the
room temperature setpoint. Optimization calculates the changeover time such that, at
the start of occupancy, the room temperature will have reached the setpoint of
NORMAL 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 [ min ] = ( T - T
Rw RM
where:
t Forward shift
T Setpoint of NORMAL room temperature
Rw
T Room model temperature
RM
k Building time constant in hours
t
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.
10.4.8

Boost heating

For boost heating, a room temperature setpoint boost can be set.
After changeover to the NORMAL temperature, the higher room temperature setpoint
applies, resulting in an appropriately higher flow temperature setpoint.
D.h.w. heating during boost heating does not affect the latter.
T
R
T
Rw
T
Rw
T
Rw
t Time
T Room temperature
R
T Setpoint of NORMAL room temperature
Rw
T Setpoint of REDUCED room temperature
Rw
TRx Actual value of the room temperature
TRw Room temperature setpoint
∆TRw Boost of room temperature setpoint (with boost heating)
Duration of boost:
• When using a room temperature sensor, boost heating is maintained until the room
temperature has reached the setpoint of NORMAL heating. Then, that setpoint will be
used again
• When using no room temperature sensor, the room model calculates how long boost
heating will be maintained. The duration is determined according to the following for-
mula
T
Rw
t [ h ] = 2
1 *
T – T
Rw
The duration of the boost is limited to 2 hours.
Basic Documentation RVL471
10 Function block "Space heating"
) 3 k
* t
T
Rw
T
Rx
T k
RM1 t
*
20
Rw
t
CE1P2524E
23.10.2002